Press Releases

  • La UPR en Arecibo y National Geographic exploran la Tierra y el Universo Por Arislyn Toledo SamalotArecibo, PR - La Universidad de Puerto Rico en Arecibo se convertirá este próximo jueves, 15 de marzo de 2018 en escenario del pre-estreno de la ...
    Posted Mar 7, 2018, 8:12 PM by Abel Mendez
  • The Weird! Signal The Weird! Signal from Ross 128 detected in the May 2017 campaign (enclosed in the red frame).Last week we distributed a press release announcing the Planetary Habitability Laboratory’s ...
    Posted Jul 21, 2017, 11:45 AM by Abel Mendez
  • A New Search for Extrasolar Planets from the Arecibo Observatory Barnard's Star will be Studied Simultaneously from Different ObservatoriesThe National Science Foundation’s Arecibo Observatory and the Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo ...
    Posted Jul 14, 2017, 6:25 AM by Abel Mendez
  • Most Planets are Colder than Thought Rocky planets in elliptical orbit experience hot and cold periods sometimes crossing the habitable zone. The new study provides a way to quantify whether these planets are able to support ...
    Posted Feb 23, 2017, 5:13 PM by Abel Mendez
  • Sailing to the Nearest Stars Artist concept of an Autonomous Active Sail (AAS) approaching the potentially habitable exoplanet Proxima b. The reflection of Proxima Centauri and background stars are seen on the mirror-like surface ...
    Posted Feb 1, 2017, 4:57 AM by Abel Mendez
  • A Potentially Habitable World in Our Nearest Star Proxima b was added to the Habitable Exoplanets CatalogAn international team of astronomers from the Pale Red Dot campaign have found evidence of a potentially habitable world orbiting the ...
    Posted Aug 25, 2016, 3:23 AM by Abel Mendez
  • New Book Describes the Search for Habitable Extrasolar Planets What does it take to consider a planet potentially habitable? If a planet is suitable for life, could life be present? Is life on other planets inevitable? Even though there ...
    Posted Jun 28, 2016, 9:47 AM by Abel Mendez
  • Científicos boricuas publican libro sobre mundos habitables Aunque no existe evidencia científica de la existencia de seres extraterrestres, sí se está acumulando evidencia sólida de la existencia de muchos otros planetas en otras estrellas, también conocidos como ...
    Posted Jun 19, 2016, 9:28 AM by Abel Mendez
  • Goldilocks: A Visualization of Potentially Habitable Worlds Goldilocks ( is an interactive space data visualization providing new ways to see & learn about the planets that fall within the “Circumstellar Habitable Zone (CHZ),” also known as ...
    Posted Dec 17, 2015, 2:21 AM by Abel Mendez
  • Alien Worlds Around Alien Stars New collaboration to study star-planet magnetic interactions. Caption: Artistic representation of the magnetic field (red lines) around a potentially habitable world (Credit: PHL @ UPR Arecibo). The Planetary Habitability Laboratory ...
    Posted Sep 16, 2015, 6:02 AM by Abel Mendez
  • First Earth-like Worlds Workshop Scientists from Puerto Rico get together to study habitable planets. One of the main goals of exoplanet science is the detection and characterization of Earth-like planets. So far, there ...
    Posted Apr 7, 2015, 1:41 AM by Abel Mendez
  • A Nearby Super-Earth with the Right Temperature but Extreme Seasons Artistic representation of the potentially habitable Super-Earth Gliese 832 c against a stellar nebula background. Credit: PHL @ UPR Arecibo, NASA Hubble, Stellarium.UPDATE: Check figure 5 for an alternative ...
    Posted Jun 29, 2014, 11:41 PM by Abel Mendez
  • Oldest Known Potentially Habitable Exoplanet Found Artistic representation of the potentially habitable world Kapteyn b with the globular cluster Omega Centauri in the background. It is believed that the Omega Centauri is the remaining core of ...
    Posted Jun 3, 2014, 3:59 PM by Abel Mendez
  • 100 Million Planets in our Galaxy May Harbor Complex Life Many Worlds with Complex Life (Credit: PHL @ UPR Arecibo, NASA, Richard Wheeler @Zephyris)One Percent of All Exoplanets May Be Suitable for Complex OrganismsThe number of planets on which ...
    Posted May 29, 2014, 12:34 PM by Abel Mendez
  • First Potentially Habitable Terran World Kepler-186 is a stellar system of five planets with an Earth-size world in the habitable zone.Simulated comparison of a sunset on Kepler-186f and Earth. On Kepler ...
    Posted Apr 17, 2014, 11:11 AM by Abel Mendez
  • Stars with Multiple Habitable Planets Might be Common Four new nearby potentially habitable planet candidates, two of them in the same star system.An international team of astronomers led by Mikko Tuomi from the University of Hertfordshire announced ...
    Posted Mar 4, 2014, 1:10 AM by Abel Mendez
  • One thousand exoplanets in two decades The milestone of 1,000 confirmed exoplanets was surpassed today after twenty-one years of discoveries. The long-established and well-known Extrasolar Planet Encyclopedia now lists 1,010 confirmed ...
    Posted Oct 22, 2013, 11:46 AM by Abel Mendez
  • The Top 12 Habitable Exoplanets * planet candidate CREDIT: PHL @ UPR AreciboBy Dirk Schulze-Makuch According to the Exoplanet Catalog maintained by the Planetary Habitability Laboratory (PHL) of the University of Puerto Rico at Arecibo ...
    Posted Sep 16, 2013, 12:04 PM by Abel Mendez
  • A Close-up View of Earth from Mercury and Saturn The 'Bright Blue Marble' and the 'Pale Blue Dot' TogetherHere are actual satellite images of Earth near the moment and the angle the pictures from Cassini and Messenger were ...
    Posted Jul 23, 2013, 3:09 AM by Abel Mendez
  • A Nearby Star with Three Potentially Habitable Worlds The star Gliese 667C is now the best candidate for harboring habitable worlds. Our Solar System has only one habitable planet, or maybe two if you count Mars’ past when ...
    Posted Jun 26, 2013, 4:21 AM by Abel Mendez
  • Asteroid 1998 QE2 Observed by the Arecibo Observatory Arecibo Observatory took radar images of asteroid 1998 QE2 and its moon as the space rock sailed safely past earth. The sequence of images show a dark, cratered asteroid 3 ...
    Posted Jun 10, 2013, 12:07 PM by Abel Mendez
  • What's new in the NASA Kepler data? Many new potentially habitable worlds waiting to be confirmedLast week NASA’s Kepler mission added 1,924 new objects of interest to its list of 2,713 exoplanet candidates ...
    Posted Jun 4, 2013, 6:52 PM by Abel Mendez
  • Ten potentially habitable exoplanets now Astronomers led by Sarah Ballard from the University of Washington announced the discovery of Kepler-61b, a superterran exoplanet orbiting near the inner edge of the habitable zone of a ...
    Posted Apr 26, 2013, 10:58 AM by Abel Mendez
  • NASA Kepler Discovers New Potentially Habitable Exoplanets Two new exoplanets discovered by NASA Kepler, Kepler-62e and Kepler-62f, were added to the Habitable Exoplanets Catalog. The two planets are part of a planetary systems of five ...
    Posted Apr 19, 2013, 3:08 AM by Abel Mendez
  • Searching for a Pale Blue SPHERE in the Universe A New Approach to Search for Earth-like WorldsThe Planetary Habitability Laboratory (PHL) is now searching for Earth-like worlds. The PHL maintains the Habitable Exoplanets Catalog (HEC) in ...
    Posted Feb 18, 2013, 5:29 PM by Abel Mendez
  • A New Habitable Zone The number of potentially habitable exoplanets will be impactedA team of astronomers from Penn State led by Ravi Kumar Kopparapu and Ramses Ramírez, also PHL collaborators, announced a redefinition ...
    Posted Jan 29, 2013, 7:59 AM by Abel Mendez
  • Famoso Descubridor de Planetas Extrasolares Visita a Puerto Rico Steven Vogt ofrece una conferencia sobre planetas habitables en el Observatorio de AreciboSe ha confirmado la existencia de casi 900 planetas alrededor de otras estrellas y cientos más que ...
    Posted Jan 13, 2013, 6:59 AM by Abel Mendez
  • "My God, it's full of planets! They should have sent a poet." NASA Kepler hints at over 250 new potentially habitable worlds NASA Kepler released last month 18,406 planet-like detection events from its last three year mission to search for ...
    Posted Jan 3, 2013, 4:47 PM by Abel Mendez
  • Two Nearby Habitable Worlds? Toumi et al. 2012 announced the potential discovery of five super-earth exoplanets around Tau Ceti with one potentially habitable. However, their data suggest that not only one but two ...
    Posted Dec 28, 2012, 11:26 AM by Abel Mendez
  • The Potentially Habitable Universe Around Us More exoplanets than expected in the first year of the Habitable Exoplanets Catalog.The first confirmed extrasolar planets, or exoplanets, were discovered from the Arecibo Observatory twenty years ago, in ...
    Posted Dec 5, 2012, 9:26 PM by Abel Mendez
  • Conferencia: Mundos Habitables y la Búsqueda de Vida Extraterrestres Ven y conoce los planetas que pudieran albergar vida extraterrestreEstamos en el principio de una nueva era en donde empezamos a descubrir planetas en otras estrellas que pudieran ser ...
    Posted Nov 22, 2012, 7:22 PM by Abel Mendez
  • First Potential Habitable Exoplanet in a Six-Planet Star System HD 40307g is the closest habitable planet candidate around a Sun-like star.A team of European-American astronomers announced the discovery of a new potential habitable exoplanet around the ...
    Posted Nov 13, 2012, 11:19 PM by Abel Mendez
  • A Planetary System Around Our Nearest Star is Emerging Scientists are getting closer to discovering Earth-like planets close to Earth The Alpha Centauri stellar system, being our closest stars, has been a long-time destiny of science fiction ...
    Posted Oct 23, 2012, 9:10 AM by Abel Mendez
  • Conferencia sobre Mundos Habitables en el Caribbean University Durante los pasados 20 años, se han descubierto mas de 800 planetas en estrellas fuera de nuestro Sistema Solar, de los cuales unos pocos pudieran tener las condiciones necesarias para ...
    Posted Oct 19, 2012, 10:30 AM by Abel Mendez
  • A Hot Potential Habitable Exoplanet around Gliese 163 The detection of Earth-like worlds is pacing upA new superterran exoplanet (aka Super-Earth) was found in the stellar habitable zone of the red dwarf star Gliese 163 ...
    Posted Sep 3, 2012, 6:38 PM by Abel Mendez
  • Five Potential Habitable Exoplanets Now New data suggests the confirmation of the exoplanet Gliese 581g and the best candidate so far of a potential habitable exoplanet. The nearby star Gliese 581 is well known for ...
    Posted Aug 1, 2012, 9:37 AM by Abel Mendez
  • The Planetary Habitability Laboratory @ AbSciCon 2012 Discussion of current and future projects of the PHL at the NASA Astrobiology Science Conference 2012The Planetary Habitability Laboratory (PHL) is a virtual scientific and educational laboratory at the ...
    Posted Apr 13, 2012, 12:41 AM by Abel Mendez
  • Twenty-Two New Candidates in the Habitable Exoplanets Catalog The Habitable Exoplanets Catalog lists now four confirmed and forty-five unconfirmed exoplanets that are high priority targets for habitable worlds. The NASA Kepler Mission data added twenty-two new ...
    Posted Jun 30, 2012, 1:33 PM by Abel Mendez
  • A Potential Habitable Exoplanet in a Nearby Triple Star System The Habitable Exoplanets Catalog (HEC) added the nearby Gliese 667C c to its list of potential habitable exoplanets. Although more future observations are necessary to confirm the habitability of any ...
    Posted Jun 30, 2012, 1:37 PM by Abel Mendez
  • A New Online Database of Habitable Worlds. The Habitable Exoplanets Catalog, a new online database of habitable worlds. The database suggests over 15 exoplanets and 30 exomoons as potential habitable candidates. Scientists are now starting to identify ...
    Posted Jun 30, 2012, 1:40 PM by Abel Mendez
  • First system for assessing the odds of life on other worlds Methodology could be used to catalogue newly discovered exoplanets, exomoonsPULLMAN, Wash. – Within the next few years, the number of planets discovered in orbits around distant stars will likely reach ...
    Posted Dec 1, 2011, 12:29 AM by Abel Mendez
  • SER: New Scientific Visualization Tool for Exoplanets The Scientific Exoplanets Renderer (SER) is a new scientific software tool by the Planetary Habitability Laboratory (PHL) to generate photorealistic visualizations of exoplanets. SER uses physical properties from exoplanets and ...
    Posted Jun 30, 2012, 1:42 PM by Abel Mendez
  • A New View of an Ancient Habitable Planet Earth 65 Million Years AgoThe Americas 65 million years ago just before the extinction of dinosaurs after an impact in the Yucatan Peninsula (center). Our planet was warmer, had ...
    Posted Mar 9, 2013, 1:00 PM by Abel Mendez
Showing posts 1 - 43 of 43. View more »

La UPR en Arecibo y National Geographic exploran la Tierra y el Universo

posted Mar 7, 2018, 8:02 PM by Abel Mendez   [ updated Mar 7, 2018, 8:12 PM ]

Arecibo, PR - La Universidad de Puerto Rico en Arecibo se convertirá este próximo jueves, 15 de marzo de 2018 en escenario del pre-estreno de la serie One Strange Rock de National Geographic. Dicha serie explora y presenta una nueva perspectiva del planeta Tierra a través de visuales impresionantes y el conocimiento de destacados científicos y astronautas. Entre los lugares de la filmación de One Strange Rock, se incluyen al espacio y a 45 países distintos. 

One Strange Rock, la cual es dirigida por el galardonado cineasta Darren Aronofsky y narrada por el actor Will Smith, se estrenará internacionalmente el 26 de marzo de 2018 en el canal de National Geographic. En uno de sus diez capítulos, se resaltan los estudios realizados por parte del Laboratorio de Habitabilidad Planetaria (PHL) en el Observatorio de Arecibo.

El proyecto PHL es un laboratorio de la UPR en Arecibo. Este se dedica al estudio de la habitabilidad, tanto del planeta Tierra como de planetas que se encuentran dentro y fuera de nuestro sistema solar. Los estudios y descubrimientos del PHL le han otorgado un reconocimiento internacional y la serie One Strange Rock hace uso de ellos en su contenido. 

“Es impresionante la producción y calidad visual de la serie One Strange Rock, Will Smith hace un excelente trabajo al contarnos sobre el funcionamiento de la vida en nuestro planeta,” dice el profesor Abel Méndez, director del PHL y coautor del libro Searching for Habitable Worlds.

En la actualidad, el proyecto PHL estudia, desde el Observatorio de Arecibo, algunas estrellas que poseen planetas potencialmente habitables y, próximamente, realizará nuevas observaciones para las cuales se convocarán a estudiantes y personas interesadas. Se espera que estas nuevas investigaciones ayuden a entender la posibilidad de vida en otros mundos.
Las buenas nuevas de parte del PHL no culminan con el pre-estreno y las observaciones. La Universidad de Cornell, con su programa de ayuda para los estudiantes afectados tras el paso del huracán María, aceptó a dos alumnos de la UPR en Arecibo, y miembros del proyecto, para que cursen el semestre actual en dicha institución. Además, en mayo de este año, el PHL inaugurará sus nuevas instalaciones y estas serán el centro oficial de trabajo del laboratorio. A la celebración, se invitarán a importantes figuras de las ciencias y estas serán testigos de la presentación de algunos de los logros más significativos del laboratorio.

El pre-estreno del primer capítulo de la serie One Strange Rock se llevará a cabo en el Anfiteatro de Enfermería de la UPR en Arecibo el jueves, 15 de marzo de 2018 a las 9:00 am. La actividad es organizada por la profesora y directora del Laboratorio Multiuso de Ciencia Integrada (ISMuL), Glorymill Santiago. El profesor Méndez, por su parte, presentará el evento y discutirá algunos datos relacionados al estreno oficial de la serie.

Para más información sobre las reservaciones y datos del pre-estreno pueden visitar la página

Imágenes Promocionales

The Weird! Signal

posted Jul 21, 2017, 8:01 AM by Abel Mendez   [ updated Jul 21, 2017, 11:45 AM ]

The Weird! Signal from Ross 128 detected in the May 2017 campaign (enclosed in the red frame).

Last week we distributed a press release announcing the Planetary Habitability Laboratory’s new collaboration with other observatories to study the red dwarf stars Barnard’s Star and Ross 128. We wanted to observe Barnard’s Star because it is a nearby star that might have planets and is currently being observed by the Red Dots project. We also wanted to observe, again, Ross 128 because in our previous observing campaign performed in May 2017 using the Arecibo Observatory we detected some peculiar signals from this star. Our project using the Arecibo Observatory, the world’s most active and most sensitive single-dish radio telescope, was originally aimed at searching for radio emissions from red dwarf stars intended to understand their stellar activity and any star-planet interactions.

Our follow-up observations of Ross 128 got much more attention from the press than we expected, although not necessarily for the right reasons. Based on our observations, we proposed three main explanations for the source of the strange signals from the star: (1) unusual stellar activity, (2) emissions from other background objects, or (3) interference from satellite communications.

Each of these potential solutions has its own problems, and so the mystery here was that we were not able to accurately distinguish between these working hypotheses. There were other less likely possibilities, such as ground radio interference, data processing errors, among several others.

However, many people were more interested in the signals as potential proof of transmissions from an extraterrestrial intelligent civilization. Statistically, this is always the last consideration, not because such civilizations are impossible, we humans are an example, but because other possibilities had frequently arisen and no extraterrestrial civilizations have been detected yet. Nevertheless, scientists need to be open to all possibilities and explore them. The Search for Extraterrestrial Intelligence (SETI) is a field of research that is part of astrobiology, and as such pursues finding signatures of life elsewhere in the galaxy. The SETI Berkeley Research Center at the University of California, and the SETI Institute are experts in this field.

There are many other examples where strange signals detected from different observatories resulted in the discovery of new astronomical phenomena or had a mundane explanation. For example, pulsars, which were originally referred to as LGM (Little Green Men), are fast rotating neutron stars. Peryton observations at Parkes Observatory in Australia were later shown to be caused by a malfunctioning microwave oven. Other strange signals are still a mystery, such as the recently detected Fast Radio Bursts (FRB), which the Arecibo Observatory helped to confirm and was essential in establishing their extragalactic origin.

Other unexplained signals, like the Wow! Signal, are commonly cited outside of academia to be proof of extraterrestrial communications. Unexplained here does not mean inexplicable; it just means we are not able to tell which is the precise source from many possibilities.

This was precisely the case of our signal from Ross 128, which we now call the Weird! Signal. We discussed our results with many other radio astronomers, but came up with no definitive answers. This finally motivated us to request the help from SETI Berkeley and the SETI Institute teams; both of which have a lot of observational experience and know very well the various kinds of terrestrial radio emissions.

Given the attention the story received from the media, we launched a public survey to ask people on the possible explanations of the Weird! Signal. The purpose of this survey was not in any sense to try to solve the mystery, but to involve the public in the excitement of real-time science.

Nine possible explanations for the Weird signal were given to the public in the survey: (1) stellar activity, (2) other astronomical source, (3) a satellite, (4) local interference, (5) instrumental glitch, (6) error in data acquisition, (7) error in data processing or calibration, (8) pattern in noise or (9) signal from aliens (a tenth possibility, “other explanation” was also included).

Nearly 800 people participated in this informal survey (including more than 60 astronomers); the consensus was that the most likely explanation was either (1) or (2), namely an astronomical phenomenon (see figure below). Causes related to radio interference or instrumental failures were considered most unlikely. This is interesting since in the absence of solid information about the signal, most astronomers would think that these would probably be the most likely explanation.

Results of a survey conducted during the week while the Weird! Signal was investigated.

Also interesting is the fact that a non-negligible number of participants in the Survey (~200) thought the most likely explanation of the signal was that of a communication with an Extraterrestrial Intelligence (ETI). However, a similar number thought that this would only happen “in our craziest dreams”. Although we do not necessarily share none of these opinions, these results reflect the still high expectations the public has on the possibility of contacting ETI.

After a careful analysis of the observations we performed last Sunday from the Arecibo Observatory, together with SETI Berkeley using the Green Bank Telescope and the SETI Institute’s Allen Telescope Array, we are now confident about the source of the Weird! Signal. The best explanation is that the signals are transmissions from one or more geostationary satellites. This explains why the signals were within the satellite’s frequencies and only appeared and persisted for Ross 128; this star is close to the celestial equator where many geostationary satellites are located. This fact, though, does not yet explain the strong dispersion-like features of the signals (diagonal lines in the figure); however, It is possible that multiple reflections caused these distortions, but we will need more time to explore this and other possibilities.

Location of Geostationary satellites operating between 4-8 GHz in the same region of the sky as Ross 128 (yellow dot).  
Credit: Enriquez et al. (SETI Berkeley),

The Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo made many new friends from this experience. We started coordinating efforts with the Red Dots team on their search for planets around nearby stars. We had the cooperation of AAVSO and other observatories with follow-up observations. Our students from the University of Puerto Rico could be involved in the scientific process, attending observations at the Arecibo Observatory and conducting data reduction. Such an experience is invaluable to our future scientists.

Finally, this was a great experience of open science. Sometimes projects, observational campaigns or missions do not necessarily reach their objectives. The lesson here is that we all need to continue exploring and sharing results openly. Some people prefer to only learn about the successes, but others prefer science in real-time, no matter the end result.

Media Contacts


    Prof. Abel Méndez, Director, PHL @ UPR Arecibo:

    Prof. Jorge Zuluaga, Institute of Physics / FCEN - Universidad de Antioquia:

A New Search for Extrasolar Planets from the Arecibo Observatory

posted Jul 12, 2017, 10:58 PM by Abel Mendez   [ updated Jul 14, 2017, 6:25 AM ]

Barnard's Star will be Studied Simultaneously from Different Observatories

The National Science Foundation’s Arecibo Observatory and the Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo joined the Red Dots project using the ESO’s exoplanet-hunter in the search for new planets around our nearest stars. This new collaboration will simultaneously observe in both the optical and radio spectrum Barnard’s Star, a popular star in the science fiction literature.

Barnard's star is a low-mass red dwarf almost six light-years away and the second-closest stellar system to our Sun after the Alpha Centauri triple-star system. There are hints of a possible super-Earth mass planet in a cold orbit around this star.

The Arecibo Observatory has a new campaign to observe nearby red dwarf stars with planets. The purpose of this campaign is to detect radio emissions from these stars, such as from flares, to help characterize their radiation and magnetic environment and any potential perturbations due to other bodies. These perturbations might reveal the presence of new sub-stellar objects including planets.

Barnard’s Star will be the eighth red dwarf star to be recently observed by the Arecibo Observatory. Results from Gliese 436, Ross 128, Wolf 359, HD 95735, BD +202465, V* RY Sex, and K2-18 are currently being analyzed. These observations are led by Prof. Abel Méndez, Director of the Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo in collaboration with Dr. Jorge Zuluaga from the Universidad de Antioquia in Colombia.

The Red Dots team will be joining the observations with the Arecibo Observatory of Barnard’s Star in coordination with other observatories. They are planning simultaneous photometric and spectral observations from SNO, LCO, TJO, and CARMENES from Spain, and earlier with ASH2 from Chile. All these observations will be used to understand the star but more observations using the ESO’s exoplanet-hunter by the Red Dots team will be necessary for the detection and confirmation of any new planet.

The first extrasolar planets were discovered from the Arecibo Observatory in 1992. They were three small planets named Draugr, Poltergeist, and Phobetor around the Lich Pulsar, a fast rotating neutron star that emits a beam of electromagnetic radiation. The first planet around a sun-like star was later discovered in 1995 and today we know of more than 3,500 of them. Recent observations by the Arecibo Observatory have been able to detect brown dwarfs, but no new planet yet.

The first and only time that Barnard’s Star was observed from the Arecibo Observatory was during the SETI Institute’s Phoenix Project (1998-2004). The new observations are in a different frequency (4 to 5 GHz) where radio emission from stellar flares have been observed in other similar or cooler objects. This is the first time Barnard’s Star is seen with such frequencies and sensitivity.

The observations of Barnard’s Star are next Sunday, July 16. Another star, Ross 128, will be observed again later that day because it showed potential radio emissions that require follow-up. Results from these observations will be available later that week. The Red Dots team keeps an open journal of their observational campaign.

Media Contacts


    Prof. Abel Méndez, Director, PHL @ UPR Arecibo:

    Prof. Jorge Zuluaga, Institute of Physics / FCEN - Universidad de Antioquia:

    Dr. Guillem Anglada-Escude, Queen Mary, University of London:

    Mr. Ricardo Correa, Press Officer, Arecibo Observatory:

Spanish Version

Nueva Búsqueda de Planetas Extrasolares desde El Observatorio de Arecibo

La Estrella Barnard será Estudiada Simuláneamente por varios Observatorios.

El Observatorio Arecibo y el Laboratorio de Habitabilidad Planetaria de la Universidad de Puerto Rico en Arecibo se unieron al proyecto Red Dots utilizando el detector de planetas de ESO en la búsqueda de nuevos planetas alrededor de las estrellas más cercanas al Sol. Esta nueva colaboración observará simultáneamente en el espectro óptico y de radio a la Estrella de Barnard, una estrella popular en la literatura de ciencia ficción.

La Estrella de Barnard es una pequeña enana roja a casi seis años luz de distancia siendo el segundo sistema estelar más cercano a nuestro Sol después del sistema de tres estrellas de Alpha Centauri. Existen indicios de un posible planeta de tipo Super-Tierra en una órbita fría alrededor de esta estrella.

El Observatorio de Arecibo tiene una nueva campaña para observar estrellas enanas rojas cercanas con planetas. El propósito de esta campaña es detectar las emisiones de radio de estas estrellas, tales como erupciones, para ayudar a caracterizar su radiación y su entorno magnético y cualquier posible perturbación debida a otros cuerpos. Estas perturbaciones podrían revelar la presencia de nuevos objetos sub-estelares incluyendo planetas.

La Estrella de Barnard será la octava estrella enana roja observada recientemente por el Observatorio de Arecibo. Los resultados de las estrellas Gliese 436, Ross 128, Wolf 359, HD 95735, BD +202465, V* RY Sex y K2-18 se están analizando actualmente. Estas observaciones son dirigidas por el Profesor Abel Méndez, Director del Laboratorio de Habitabilidad Planetaria de la Universidad de Puerto Rico en Arecibo y con la colaboración del Dr. Jorge Zuluaga de la Universidad de Antioquia en Colombia.

El equipo de Red Dots se unirá a las observaciones del Observatorio de Arecibo de la Estrella de Barnard en coordinación con otros observatorios. Planean observaciones fotométricas y espectrales simultáneas con los telescopios SNO, LCO, TJO y CARMENES de España, y preliminarmente con ASH2 de Chile. Todas estas observaciones serán utilizadas para entender la estrella pero se necesitarán observaciones adicionales con el detector de planetas de ESO por el equipo de Red Dots para detectar y confirmar cualquier nuevo planeta.

Los primeros planetas extrasolares fueron descubiertos en el Observatorio de Arecibo en el 1992. Son tres pequeños planetas llamados Draugr, Poltergeist y Phobetor alrededor del Pulsar Lich, una estrella de neutrones de rápida rotación que emite un haz de radiación electromagnética. El primer planeta alrededor de una estrella parecida al sol fue descubierto más tarde en el 1995 y hoy sabemos de más de 3,500 de ellos. Actualmente el Observatorio de Arecibo ha podido detectar enanas marrones pero todavía ningún planeta nuevo.

La primera y única vez que la Estrella de Barnard fue observada desde el Observatorio de Arecibo fue durante el Proyecto Phoenix del Instituto SETI (1998-2004). Las nuevas observaciones serán en una frecuencia diferente (4 a 5 GHz), donde la emisión de radio de erupciones estelares se han observado en otros objetos similares o más fríos. Esta es la primera vez que la Estrella de Barnard se estudia con tales frecuencias y sensibilidad.

Las observaciones de la Estrella de Barnard serán el próximo domingo, 16 de julio. Otra estrella, Ross 128, será observada ese día más tarde ya que demostró interesantes emisiones de radio en pasadas observaciones. Los resultados de estas observaciones estarán disponibles más adelante esa semana. El equipo de Red Dots mantiene un diario abierto de su campaña de observación.

Most Planets are Colder than Thought

posted Feb 22, 2017, 5:31 AM by Abel Mendez   [ updated Feb 23, 2017, 5:13 PM ]

Rocky planets in elliptical orbit experience hot and cold periods sometimes crossing the habitable zone. The new study provides a way to quantify whether these planets are able to support surface liquid water. Credit: PHL @ UPR Arecibo.

There Might be More Planets in the Habitable Zone

A common assumption in the search for habitable abodes beyond Earth is that the average temperature of planets always increases the more elliptical their orbit is. Now, scientists from the Planetary Habitability Laboratory (PHL) and the Arecibo Observatory in Puerto Rico have shown that planets in elliptical orbits are generally colder than previously believed.

Planets can move around their parent star in orbits that are not perfectly circular. These elliptical orbits put planets sometimes significantly closer or farther from their star, thus contributing to extreme temperature changes. This is not the case of Earth, and probably for the exoplanets orbiting the stars Proxima Centauri or TRAPPIST-1, but true for many known planets around other stars.

In the past, scientists assumed the average equilibrium temperature of a planet would increase with eccentricity because the average energy received from its star, the stellar flux, also increases with eccentricity. A new study, published in the Astrophysical Journal Letters, provides a new model that shows this is not always the case.

“A change in stellar flux does not translate accordingly to a change of temperature along elliptical orbits”, says Abel Méndez, a Planetary Astrobiologist from the PHL at the University of Puerto Rico at Arecibo and lead author of the study.

The equilibrium temperature is one of many important factors controlling the global climate of planets, from Mars-sized to Jupiter-sized worlds. The surface temperature of potentially habitable planets also depend on their equilibrium temperature and atmospheric greenhouse effect.

“We discovered this orbital cooling effect when we were not able to match the numerical models of our Habitable Exoplanet Catalog with current analytical models, so we derived a new analytical model that explains it,” says Méndez.

“If we followed some of the previous models, Mars, which is a planet with an eccentric orbit, should have an equilibrium temperature of -43 °C” , noted Edgard Rivera-Valentín, a Planetary Scientists at the Arecibo Observatory with the Universities Space Research Association and co-author of the study, “Now we’re getting -63 °C, which matches what we’ve observed.”

Hints to the orbital cooling effect described by Méndez & Rivera-Valentín appeared first in climate simulations of Earth-like planets in eccentric orbits. “Now we know that this is a universal effect not only caused by changes on the planet’s albedo, its ability to reflect stellar radiation,” says Méndez.

The study also suggests a new method to determine whether planets in elliptical orbits are within the habitable zone, the region around a star where rocky planets could support surface liquid water. This might have an impact on the number of planets considered potentially habitable, especially those initially considered too hot for life.

The effect described in the study is negligible for planets in nearly circular orbits, but strong enough to reevaluate the habitability of those in very elliptical orbits such as the planets of the red-dwarf star Wolf 1061 or even potential exomoons around warm jupiters.


Original Press Release: Most Planets are Colder than Thought

Research Paper: Méndez, Abel, & Rivera-Valentín, Edgard G., (2017) The Equilibrium Temperature of Planets in Elliptical Orbits. ApJL, 837, L1 (

Media Contact

Abel Méndez, PHL @ UPR Arecibo, @ProfAbelMendez

Edgard Rivera-Valentín, Arecibo Observatory/USRA, @PlanetTreky

Anilyn Diaz Hernandez, Press Officer, UPR Arecibo, @UPRA_Oficial

Additional Information

Prof. Abel Méndez is a Planetary Astrobiologist and Associate Professor of Physics and Astrobiology at the University of Puerto Rico at Arecibo. He is the Director of the PHL, a laboratory dedicated to studies of the habitability of Earth, the Solar System, and extrasolar planets. He is also the co-author of the popular science book Searching for Habitable Worlds.

Dr. Edgard Rivera-Valentín is a Planetary Scientist at the Arecibo Observatory (AO) with the Universities Space Research Association (USRA). At AO he conducts observations of NEOs as part of NASA's Near-Earth Object Observations program. His research focuses on astrobiology and Solar System formation.

The Planetary Habitability Laboratory is a project of the University of Puerto Rico at Arecibo supported by the National Science Foundation, the NASA Astrobiology Institute, and the University of Puerto Rico. Computational resources are provided by the UPR’s High Performance Computing Facility.

The Arecibo Observatory is a facility of the National Science Foundation operated by SRI International in alliance with the Universities Space Research Association (USRA) and Ana G. Méndez-Universidad Metropolitana. The Planetary Radar Program at AO is fully funded by NASA through grants from the Near-Earth Object Observations program managed by USRA.

Sailing to the Nearest Stars

posted Feb 1, 2017, 12:01 AM by Abel Mendez   [ updated Feb 1, 2017, 4:57 AM ]

Artist concept of an Autonomous Active Sail (AAS) approaching the potentially habitable exoplanet Proxima b. The reflection of Proxima Centauri and background stars are seen on the mirror-like surface of the sail. Four communication lasers beams are shown firing from its corners to transmit information back to Earth. The lower right panels of the sail are in the process of becoming darker to change its direction and orientation from differences in radiation pressure. Credit: PHL @ UPR Arecibo.

Space travel visionaries solve the problem of interstellar slowdown at our stellar neighbour

In April last year, billionaire Yuri Milner announced the Breakthrough Starshot Initiative. He plans to invest 100 million US dollars in the development of an ultra-light light sail that can be accelerated to 20 percent of the speed of light to reach the Alpha Centauri star system within 20 years. The problem of how to slow down this projectile once it reaches its target remains a challenge. René Heller of the Max Planck Institute for Solar System Research in Göttingen and his colleague Michael Hippke propose to use the radiation and gravity of the Alpha Centauri stars to decelerate the craft. It could then even be rerouted to the red dwarf star Proxima Centauri and its potential Earth-like planet Proxima b.

In the recent science fiction film Passengers, a huge spaceship flies at half the speed of light on a 120-year-long journey toward the distant planet Homestead II, where its 5000 passengers are to set up a new home. This dream is impossible to realize at the current state of technology. “With today’s technology, even a small probe would have to travel nearly 100,000 years to reach its destination,” René Heller says.

Notwithstanding the technical challenges, Heller and his colleague Michael Hippke wondered, “How could you optimize the scientific yield of this type of a mission?” Such a fast probe would cover the distance from the Earth to the Moon in just six seconds. It would therefore hurtle past the stars and planets of the Alpha Centauri system in a flash.

The solution is for the probe’s sail to be redeployed upon arrival so that the spacecraft would be optimally decelerated by the incoming radiation from the stars in the Alpha Centauri system. René Heller, an astrophysicist working on preparations for the upcoming Exoplanet mission PLATO, found a congenial spirit in IT specialist Michael Hippke, who set up the computer simulations.

The two scientists based their calculations on a space probe weighing less than 100 grams in total, which is mounted to a 100,000-square-metre sail, equivalent to the area of 14 soccer fields. During the approach to Alpha Centauri, the braking force would increase. The stronger the braking force, the more effectively the spacecraft’s speed can be reduced upon arrival. Vice versa, the same physics could be used to accelerate the sail at departure from the solar system, using the sun as a photon cannon.

The tiny spacecraft would first need to approach the star Alpha Centauri A as close as around four million kilometres, corresponding to five stellar radii, at a maximum speed of 13,800 kilometres per second (4.6 per cent of the speed of light). At even higher speeds, the probe would simply overshoot the star.

During its stellar encounter, the probe would not only be repelled by the stellar radiation, but it would also be attracted by the star’s gravitational field. This effect could be used to deflect it around the star. These swing-by-manoeuvres have been performed numerous times by space probes in our solar system. “In our nominal mission scenario, the probe would take a little less than 100 years – or about twice as long as the Voyager probes have now been travelling. And these machines from the 1970s are still operational,” says Michael Hippke.

Theoretically, the autonomous, active light sail proposed by Heller and Hippke could settle into a bound orbit around Alpha Centauri A and possibly explore its planets. However, the two scientists are thinking even bigger. Alpha Centauri is a triple star system. The two binary stars A and B revolve around their common centre of mass in a relatively close orbit, while the third star, Proxima Centauri, is 0.22 light years away, more than 12,500 times the distance between the Sun and the Earth.

The sail could be configured so that the stellar pressure from star A brakes and deflects the probe toward Alpha Centauri B, where it would arrive after just a few days. The sail would then be slowed again and catapulted towards Proxima Centauri, where it would arrive after another 46 years − about 140 years after its launch from Earth.

An interstellar mission of an Autonomous Active Sail (AAS) to the nearest three stars. The sail uses an active reflective surface to change its direction and orientation from photogravitational assists from the stars, including the Sun. A light 90 grams sail could take nearly 100 years to reach Alpha Centauri A and another 50 years to Proxima Centauri. Many engineering challenges will need to be solved to pack enough communication and science instruments in such light but wide interstellar probes. Credit: PHL @ UPR Arecibo.

Proxima Centauri caused a sensation in August 2016 when astronomers at the European Southern Observatory (ESO) discovered an exoplanet companion that is about as massive as the Earth and that orbits the star in its so-called habitable zone. This makes it theoretically possible for liquid water to exist on its surface – water being a key prerequisite for life on Earth.

“This finding prompted us to think about the possibility of stopping a high-velocity interstellar lightsail at Proxima Centauri and its planet,” says René Heller. The Max Planck researcher and his colleague propose another change to the strategy for the Starshot project: instead of a huge energy-hungry laser, the Sun’s radiation could be used to accelerate a nanoprobe beyond the solar system. “It would have to approach the Sun to within about five solar radii to acquire the necessary momentum,” Heller says.

The two astronomers are now discussing their concept with the members of the Breakthrough Starshot Initiative, to whom they owe the inspiration for their study. “Our new mission concept could yield a high scientific return, but only the grandchildren of our grandchildren would receive it. Starshot, on the other hand, works on a timescale of decades and could be realized in one generation. So we might have identified a longterm, follow-up concept for Starshot,” Heller says.

Although the new scenario is based on a mathematical study and computer simulations, the proposed hardware of the sail is already being developed in laboratories today: “The sail could be made of graphene, an extremely thin and light but mega-tough carbon film,” René Heller says. The film would have to be blanketed by a highly reflective cover to endure the harsh conditions of deep space and the heat near the destination star.

The optical and electronic systems would have to be tiny. But if you were to remove all the unnecessary components from a modern smartphone, “only a few grams of functional technology would remain.” Moreover, the lightweight spacecraft would have to navigate independently and transmit its data to Earth by laser. To do so, it would need energy, which it could harness from the stellar radiation.

Breakthrough Starshot therefore poses daunting challenges that have so far only been solved theoretically. Nevertheless, “many great visions in the history of mankind had to struggle with seemingly insurmountable obstacles,” Heller says. “We could soon be entering an era in which humans can leave their own star system to explore exoplanets using fly-by missions.”



Dr René Heller 
Solar and Stellar Interiors Department 
Max Planck Institute for Solar System Research, Göttingen

Dipl.Volksw. Michael Hippke

A Potentially Habitable World in Our Nearest Star

posted Aug 17, 2016, 4:40 AM by Abel Mendez   [ updated Aug 25, 2016, 3:23 AM ]

Proxima b was added to the Habitable Exoplanets Catalog

An international team of astronomers from the Pale Red Dot campaign have found evidence of a potentially habitable world orbiting the closest star to Earth, Proxima Centauri, a cool red-dwarf slightly older than the Sun [1]. The planet, named Proxima b, has a minimum mass of 1.3 times that of Earth and orbits its parent star every 11.2 days, receiving about 70% the energy Earth receives from the Sun.

A potentially habitable world is a planet around another star that might support liquid water on its surface and therefore lies within the so-called habitable zone. Though currently we cannot tell exactly how habitable such planets are because we can not investigate their geologic or atmospheric composition, it is believed that small planets located in the habitable zone, just like Earth and now Proxima b, would be more likely to have the right conditions for life as we know it.

Proxima b was added to the Habitable Exoplanets Catalog (HEC) [2] as one of the best objects of interest for the search for life in the universe. The planet orbits well within the conservative habitable zone of Proxima Centauri. Additionally, Proxima b is now not only the closest potentially habitable planet to Earth (4.2 light years away), but it is also the most similar to Earth (ESI = 0.87) [3], with respect to Earth’s mass and insolation.

Other factors, though, make Proxima b quite different from Earth. It is probably tidally-locked, always giving the same face to its star. The illuminated side might be too hot, while the dark side too cold for liquid water or life. A thick atmosphere or a large ocean, though, could regulate the temperatures across the planet, but we do not know if this is the case [4].

Probably the most detrimental factor for the habitability of Proxima b is the activity of its parent star, which produces strong magnetic fields, flares, and high UV and X-ray fluxes as most red-dwarf stars do. These factors may lead to the atmospheric and water loss of the planet, but would not necessarily preclude habitable conditions [5][6][7]. Should Proxima b have a magnetic field, much like Earth does, it would potentially be shielded from such devastating forces. 

The mass of Proxima b suggests a rocky composition, but we do not know its radius to evaluate its bulk density [8]. The planet could be between 0.8 to 1.4 Earth radii depending on composition [9] and if rocky should be about 10% larger than Earth. However, Proxima b could be larger given that we only know its minimum mass.

Statistically, it is not expected to have a potentially habitable world so close to Earth due to their expected low occurrence in the galaxy. It is estimated that 24% of red-dwarf stars have an Earth-sized planet (1 to 1.5 RE) in the optimistic habitable zone [10]. This corresponds to an average separation of eight light years between them in the Solar Neighborhood (248 red-dwarfs within 10 parsecs) [11]. Therefore, the probability of having a potentially habitable world orbiting our nearest star is less than 10%. Either Proxima b was a lucky find or these worlds are more common than previously thought.

The most exciting aspect of this discovery is that Proxima b is relatively close enough to Earth for detailed studies in the next years by current and future observatories. Other known potentially habitable worlds, especially those from the NASA Kepler primary mission, are too far away to get any information about their atmosphere or composition with current technology. Projects like StarShot are even considering the possibility of reaching the stars with miniaturized space probes, but this exciting approach might take many decades.

Proxima b is an excellent object for future characterization via transit or direct imaging in search for biosignatures [12]. There is a 1.5% chance that Proxima b transits its parent star [13]. Such transits will take 53 minutes as seen from Earth and will produce a notable 0.5% decrease on the brightness of Proxima Centauri [14]. Direct imaging in the next decades might even provide information about the surface and weather of Proxima b [15].

In any case, Proxima b is now one of the prime targets to understand the extension of our habitable universe in years to come. Red-dwarf stars are the most common star in our galaxy, comprising about 75% of the stars. If we find out that planets around red-dwarf stars, such as Proxima b, are in fact not habitable then the ‘real estate’ for life in the universe will be instead very small. The answer lies 4.2 light years away waiting for us.


[1] Anglada-Escudé, Guillem , Amado, Pedro J., Barnes, John,
Butler, R. Paul, Coleman, Gavin A. L., de la Cueva, Ignacio,
Dreizler, Stefan, Endl, Michael, Giesers, Benjamin,
Jeffers, Sandra V., Jenkins, James S., Jones, Hugh R. A., Kiraga, Marcin, Kürster, Martin, López-González, María J., Marvin, Christopher J., Berdiñas, Zaira M., Morales, Nicolás,
Morin, Julien, Nelson, Richard P., Ortiz, José L.,
Ofir, Aviv, Paardekooper, Sijme-Jan, Reiners, Ansgar,
Rodríguez, Eloy, Rodríguez-López, Cristina, Sarmiento, Luis F.,
Strachan, John P., Tsapras, Yiannis, Tuomi, Mikko,
Zechmeister, Mathias. (2016). A terrestrial planet candidate in a temperate orbit around Proxima Centauri. Nature XX, XX.

[2] The Habitable Exoplanets Catalog (HEC) tracks since 2011 all potentially habitable worlds discovered by all ground and space telescopes around the world. The HEC is an initiative of the Planetary Habitability Laboratory (PHL) of the University of Puerto Rico at Arecibo (UPR Arecibo).

[3] The Earth Similarity Index (ESI) is a measure of Earth-likeness from zero (no similarity) to one (identical to Earth) given some known planetary properties. For exoplanets the ESI is based on stellar flux and either the mass or radius of the planets. Since habitability depends on many other factors it is not known if planets with similar mass and stellar flux to Earth (i.e., ESI values closer to one) are also in general more habitable. 

[4] Kopparapu, R. kumar, Wolf, E. T., Haqq-Misra, J., Yang, J., Kasting, J. F., Meadows, V., … Mahadevan. (2016). The Inner Edge of the Habitable Zone for Synchronously Rotating Planets around Low-mass Stars Using General Circulation Models. The Astrophysical Journal, 819(1), 84.

[5] Vidotto, A. A., Jardine, M., Morin, J., Donati, J.-F., Lang, P., & Russell, A. J. B. (2013). Effects of M dwarf magnetic fields on potentially habitable planets. Astronomy & Astrophysics, 557, A67.

[6] Zuluaga, J. I., Bustamante, S., Cuartas, P. A., & Hoyos, J. H. (2013). The Influence of Thermal Evolution in the Magnetic Protection of Terrestrial Planets. The Astrophysical Journal, 770(1), 23.

[7] Bolmont, E., Selsis, F., Owen, J. E., Ribas, I., Raymond, S. N., Leconte, J., & Gillon, M. (2016). Water loss from Earth-sized planets in the habitable zones of ultracool dwarfs: Implications for the planets of TRAPPIST-1. arXiv:1605.00616 [astro-Ph]. Retrieved from

[8] Rogers, L. A. (2015). Most 1.6 Earth-radius Planets are Not Rocky. The Astrophysical Journal, 801(1), 41.

[9] Seager, S., Kuchner, M., Hier-Majumder, C. A., & Militzer, B. (2007). Mass-Radius Relationships for Solid Exoplanets. The Astrophysical Journal, 669(2), 1279.

[10] Dressing, C. D., & Charbonneau, D. (2015). The Occurrence of Potentially Habitable Planets Orbiting M Dwarfs Estimated from the Full Kepler Dataset and an Empirical Measurement of the Detection Sensitivity. The Astrophysical Journal, 807(1), 45.

[11] RECONS (2012) Census Of Objects Nearer Than 10 Parsecs

[12] Seager, S., Bains, W., & Petkowski, J. j. (2016). Toward a List of Molecules as Potential Biosignature Gases for the Search for Life on Exoplanets and Applications to Terrestrial Biochemistry. Astrobiology, 16(6), 465–485.

[13] Stevens, D. J., & Gaudi, B. S. (2013). A Posteriori Transit Probabilities. Publications of the Astronomical Society of the Pacific, 125(930), 933–950.

[14] Burke, C. J., & McCullough, P. R. (2014). Transit and Radial Velocity Survey Efficiency Comparison for a Habitable Zone Earth. The Astrophysical Journal, 792(1), 79.

[15] Fujii, Y., Kawahara, H., Suto, Y., Taruya, A., Fukuda, S., Nakajima, T., & Turner, E. L. (2010). Colors of a Second Earth: Estimating the Fractional Areas of Ocean, Land, and Vegetation of Earth-like Exoplanets. The Astrophysical Journal, 715(2), 866.

Note: The PHL @ UPR Arecibo created an independent assessment, and produced multimedia content for ESO and the general public as part of the announcement of the Proxima b discovery. We acknowledge the collaboration of Guillem Anglada-Escudé from Queen Mary University of London (lead scientist of the discovery), the ESO Public Information Office, Edgard Rivera-Valentín from the Arecibo Observatory (USRA), the computational resources of the HPCf of the University of Puerto Rico, the University of Puerto Rico at Arecibo, and the music of Lyford Rome.

Additional Resources

Guillem Anglada-Escudé (Lead Scientist)
Queen Mary University of London

Abel Méndez, (Results from the Habitable Exoplanets Catalog)
PHL @ UPR Arecibo


Video 01. The Pale Red Dot campaign aimed to find a planet orbiting our nearest stellar neighbor, Proxima Centauri. Incredibly, the quest succeeded and the team did indeed find a planet. Even more exciting, the planet, Proxima b, falls within the habitable zone of its host star. The newly discovered Proxima b is by far the closest potential abode for alien life. Credit: ESO.

Video 02. This is an artistic interpretation of the potentially habitable planet around our nearest star, Proxima Centauri. The planet is represented here as a mostly desert-like, tidally-locked world with shallow oceans and a strong atmospheric circulation allowing heat exchange between the light and dark hemispheres. The star and orbit are to scale, but the planet was enlarged (x30) for visibility. Video was rendered by the PHL’s SER software. Additional versions of this video are available hereCredit: PHL @ UPR Arecibo, ESO. Background music ‘Atmospherics Final’ by Lyford Rome.

Video 03. This is a one-minute real-time simulation showing a close encounter with Proxima b at 20% the speed of light. The StarShot Initiative is planning a mission to the Alpha Centauri stellar systems at such speed. The same animation would take over two days to complete at the speed of NASA's New Horizons (~16 km/s)Video was rendered by the PHL’s SER software. Additional versions of this video are available here. Credit: PHL @ UPR Arecibo, ESO. Background music ‘Into the Black’ by Lyford Rome.

Video 04. This is a simulation of the possible surface temperatures of a tidally-locked Proxima b, always giving the same face to its star. The simulations show the large temperature differences between the permanent daylight and nightside hemispheres. This assumes that an ocean and atmosphere transfers heat effectively around the planet, but we do not know yet if this is the case. The temperature range includes habitable conditions, even for complex life (0-50°C). However, Proxima b may also be exposed to high UV and X-ray fluxes that could challenge any presence of life. Proxima b seems to be an extreme, but very interesting planet by terrestrial standards. Additional versions of this video are available here. Credit: M. Turbet/I. Ribas/ESO.


Figure 01. Summary of the properties of the Proxima Centauri System. The size of the red-dwarf star Proxima Centauri and its planet Proxima b are approximately to scale in this diagram. The planet is at a distance of almost 20 times the Earth-Moon distance (74 star radii) from its star. For comparison, Earth is at 407 times the Earth-moon distance from the Sun. Credit: PHL @ UPR Arecibo.

Figure 02. Size comparison of Earth and Proxima b. Proxima b might be about 10% larger than Earth given its minimum mass (1.3 Earth masses) and assuming a rocky composition. This particular artistic representation depicts Proxima b as a mostly desert-like, tidally-locked world with shallow oceans maintained by heat-exchange in a dense atmosphere. Credit: PHL @ UPR Arecibo, NASA EPIC Team.

Figure 03. Size comparison of the red-dwarf star Proxima Centauri and its planet Proxima b with some Solar System bodies, including Earth, Jupiter, Saturn, and the Sun. The color of Proxima Centauri and the Sun were enhanced. Credit: PHL @ UPR Arecibo.

Figure 04. The Alpha Centauri family is composed of three stars. The G-star Alpha Centauri A and its K-star companion B orbit each other in a very eccentric orbit separated from 11 to 36 astronomical units (AU). Proxima Centauri is believed to be also bound to this system, but at a distance of 15,000 AU. Our G-star Sun is shown for scale. The color of the stars were adjusted to approximately imitate the human eye perception. Credit: PHL @ UPR Arecibo.

Figure 05. Simulated comparison of a sunset on Earth and Proxima b. The red-dwarf star Proxima Centauri appears almost three times bigger than the Sun in a redder and darker sky. Red-dwarf stars appear bigger in the sky than sun-like stars, even though they are smaller. This is because they are cooler and the planets have to be closer to them to maintain temperate conditions. The original photo of the beach was taken at Playa Puerto Nuevo in Vega Baja, Puerto RicoCredit: PHL @ UPR Arecibo.

Figure 06. Simulated comparison of a sunset on Earth with that of four known potentially habitable worlds. The sunset from the planets with red-dwarf stars (Proxima b, Gliese 667C c, and Wolf 1061 c) appear darker, but with a bigger star than those with K-stars (Kepler-442 b) or sun-like stars. Red-dwarf stars appear bigger in the sky than sun-like stars, even though they are smaller, because they are cooler and the planets have to be closer to them to maintain temperate conditions. The original photo of the beach was taken at Playa Puerto Nuevo in Vega Baja, Puerto RicoCredit: PHL @ UPR Arecibo.

Figure 07. Comparison of the visual appearance of Earth illuminated by the Sun (left) and a red-dwarf star (right). The light from a red-dwarf star, such as Proxima Centauri, makes Earth look darker and with a pale green-yellow tone instead of the familiar pale blue. Credit: PHL @ UPR Arecibo, NASA EPIC Team.

Figure 08. Artistic representations of the top 10 potentially habitable worlds in the Habitable Exoplanets Catalog, now including Proxima b. They are sorted in this image by the Earth Similarity Index (ESI), a measure of how similar a planet is in size (given by radius or mass) and stellar flux (insolation) to Earth. Planetary habitability depends on many factors and it is not known if planets with a similar size and insolation as Earth are generally habitable. Earth, Mars, Jupiter, and Neptune for scale. Planet candidates indicated with asterisks. Credit: PHL @ UPR Arecibo.

Figure 09. Artistic representations of the top 10 potentially habitable worlds in the Habitable Exoplanets Catalog, now including Proxima b. They are sorted in this image by distance from Earth in light years. Earth, Mars, Jupiter, and Neptune for scale. Planet candidates indicated with asterisks. Credit: PHL @ UPR Arecibo.

Figure 10. Orbit of Proxima b assuming a maximum eccentricity of 0.350, but its actual orbit might be less eccentric (closer to the red dotted circle). The size of the habitable zone is shown in a green shade and the ice-line with a blue dotted circle. The orbit is well within the tidal-lock radius (outside of the frame). Credit: PHL @ UPR Arecibo.

Figure 11. This figure shows all planets near the habitable zone, now including Proxima b (darker green shade is the conservative habitable zone and the lighter green shade is the optimistic habitable zone). Only those planets less than 10 Earth masses or 2.5 Earth radii are labeled. Some are still unconfirmed (* = unconfirmed). Size of the circles corresponds to the radius of the planets (estimated from a mass-radius relationship when not available). Credit: PHL @ UPR Arecibo.

Figure 12. Sky map with all the stars with known potentially habitable planets (yellow circles). The star Proxima Centauri is close to the center bottom of the figure. Click image to enlarge. Credit: PHL @ UPR AreciboJim Cornmell.

New Book Describes the Search for Habitable Extrasolar Planets

posted Jun 28, 2016, 9:34 AM by Abel Mendez   [ updated Jun 28, 2016, 9:47 AM ]

What does it take to consider a planet potentially habitable? If a planet is suitable for life, could life be present? Is life on other planets inevitable? Even though there is no scientific evidence of extraterrestrial life, scientists continue to gather and analyze astronomical data, leading to a better understanding of what it takes to find such life and where are the best planets to find it.

Scientists Prof. Abel Méndez (Associate Professor of Physics and Director of the Planetary Habitability Laboratory, University of Puerto Rico at Arecibo) and Dr. Wilson González-Espada (Associate Professor of Physics and Science Education, Morehead State University, Kentucky) just published a book describing the search for potentially habitable extrasolar planets and what are the best candidates so far. 

Searching for Habitable Worlds: An Introduction, is a fun and accessible book for everyone, from school students and the general public to amateur astronomers of all ages. The use of non-technical language and abundant illustrations make this a quick read to inform everyone about the latest news in the search for other planets that we might be able to inhabit. The book is part of the Institute of Physics/Morgan & Claypool Publishers book series called “IOP Concise Physics”, whose main goal is to make available shorter texts in rapidly advancing areas or topics where an introductory text is more appropriate.

After a brief discussion on why humans are hard-wired to be curious and to explore the unknown, Searching for Habitable Worlds: An Introduction describes what extrasolar planets are, how to detect them, and how to pin down potentially habitable ones. In addition, a data-driven list of the best candidates for habitability is profiled, and the next generation of scientific instruments and probes to detect extrasolar planets are identified.

According to Prof. Méndez, “detecting extrasolar planets is a complex process, but it is becoming easier as instrumentation and technologies evolve. Current methods allow scientists to determine their size, mass, temperature, orbital parameters and possible chemical composition. Only extrasolar planets with a unique combination of physical and chemical properties are classified as potentially habitable. It is also important to consider that, even if an extrasolar planet is not habitable today, it could have been habitable in the past or might potentially be habitable in the future. Earth, for instance, was not habitable nearly five billion years ago but it is now.”

Dr. González-Espada noted that although the book’s contents might sound complex or intimidating, it was carefully written to use accessible language and a lively narrative style that will motivate young people to study astronomy and other physical sciences. “Searching for Habitable Worlds: An Introduction presents topics in a very interesting way, with a minimum of technical jargon and plenty of visuals. At the same time, it highlights the fact that the search and characterization of extrasolar planets is an emerging discipline, and that plenty of breathtaking discoveries are yet to be made.”

Searching for Habitable Worlds: An Introduction is available at the Morgan & Claypool Publishers Bookstore, Amazon (Kindle), and other online book retailers.

Científicos boricuas publican libro sobre mundos habitables

posted Jun 19, 2016, 9:25 AM by Abel Mendez   [ updated Jun 19, 2016, 9:28 AM ]

Aunque no existe evidencia científica de la existencia de seres extraterrestres, sí se está acumulando evidencia sólida de la existencia de muchos otros planetas en otras estrellas, también conocidos como exoplanetas. Unos pocos de éstos parecen tener el tamaño y la órbita correcta para ser posiblemente habitables. ¿Cuántos de estos mundos pudieran ser habitables? ¿Dónde están? ¿Tendrán esos planetas vida similar a la nuestra o habitarán en ellos organismos jamás soñados por la imaginación humana?

Los científicos boricuas Prof. Abel Méndez (Catedrático Asociado en Física y Director del Laboratorio de Habitabilidad Planetaria, Universidad de Puerto Rico en Arecibo) y el Dr. Wilson González Espada (Catedrático Asociado en Física y Educación Científica, Morehead State University, Kentucky) acaban de publicar el libro Searching for Habitable Worlds. Esta publicación discute la información más reciente sobre los planetas posiblemente habitables, cómo se identifican y cuáles existen hasta el presente. 

El libro está dividido en seis ideas principales: (1) Cómo y por qué la curiosidad humana nos ha llevado a explorar las maravillas del espacio; (2) Qué son los exoplanetas y qué técnicas se usan para encontrarlos; (3) Qué es la habitabilidad planetaria y cómo se mide; (4) Qué es la "tabla periodica" de los exoplanetas y cómo ayuda a clasificar exoplanetas similares a la Tierra; (5) Cuántos exoplanetas se han descubierto hasta el presente y cúales son sus características astrofísicas principales; y (6) Qué misiones de exploración espacial están en planes para descubrir aún más mundos posiblemente habitables.

El libro Searching for Habitable Worlds es parte de la serie Libros Concisos del Instituto de Física (IOP, en inglés), una organización científica británica, sin fines de lucro, cuya meta es el avance de la física, su didáctica, investigación y aplicaciones. IOP colabora con la casa editorial norteamericana Morgan & Claypool Publishers. La serie Libros Concisos IOP incluye libros cortos en temas de rápido avance y alta relevancia a la comunidad científica.

Según el Prof. Méndez, “detectar exoplanetas es un proceso complejo, pero que que se hace cada vez más fácil con el uso de tecnologías modernas. Una vez se confirma que un exoplaneta existe, hay que determinar su tamaño, órbita y posible composición química. Para que un mundo sea habitable tiene que tener una combinación poco común de ingredientes.”

“También hay que considerar que, si un planeta no es habitable hoy, pudo haberlo sido en el pasado o serlo en el futuro. Por ejemplo, hace casi cinco billones de años nuestro planeta no era tan habitable, pero cambios geológicos y astronómicos han logrado que hoy día sí lo sea,” añadió el astrobiologo vegabajeño. 

Por su parte, el cagüeño Dr. González Espada indicó que, aunque el contenido del libro parecería complicado, el mismo está escrito en un lenguaje sencillo y accessible para jóvenes, astrónomos principiantes y el público en general. “El libro presenta los temas con la menor cantidad de palabras técnicas, y con muchísimas ilustraciones y fotos a color. La idea es que si alguien quiere conocer sobre exoplanetas y habitabilidad de una manera rápida y actualizada, nuestro libro sea una excelente consulta inicial.”

Una de las metas principales del libro es que sirva de inspiración a nuevas generaciones de jóvenes científicos. “Sólo se ha examinado a profundidad una cantidad minúscula del cielo nocturno que vemos, así que existen muchas oportunidades de estudio e investigación. Necesitamos jóvenes que lean nuestro libro y eso los motive a estudiar astronomía y otras ciencias físicas para que hagan los descubrimientos del futuro.”

El libro Searching for Habitable Worlds está disponible en la página web de Morgan & Claypool Publishers y en otras librerías electrónicas, incluyendo Amazon Kindle.

Contacto de Prensa: Viviana Tirado <>

Goldilocks: A Visualization of Potentially Habitable Worlds

posted Dec 17, 2015, 12:12 AM by Abel Mendez   [ updated Dec 17, 2015, 2:21 AM ]

Goldilocks ( is an interactive space data visualization providing new ways to see & learn about the planets that fall within the “Circumstellar Habitable Zone (CHZ),” also known as the “Goldilocks Zone.” These are the planets that are believed to have the basic required conditions to support possible life.

Commissioned by, and created for, Visualized, the creative data visualization conference which took place in New York in October 2015, Goldilocks was designed by Data Experience Designer, Jan Willem Tulp with guidance from members of the European Space Agency (ESA) & American History Museum's Earth & Planetary Science Division.

Using publicly available data from Planetary Habitability Laboratory (PHL), located at the University of Puerto Rico at Arecibo, the concept was to create a fun, engaging new way to experience and compare the planets that could potentially hold life.

Go to for a full screen view.

For press related quotes from the team involved behind the project, please contact:
About Visualized: web: | twitter: @visualized

Visualized hosts creative data visualization conferences around the world, bringing together the most innovative minds that are changing the way we communicate, understand, and interact with data. The Visualized annual flagship conference takes place in October in New York City.

About TULP interactive: web: | twitter: @JanWillemTulp

TULP interactive is an award winning Data Experience Design studio, run by Jan Willem Tulp. TULP interactive helps organizations by creating data visualizations that communicate and find insights in data. TULP interactive works for clients such as Scientific American, Nature, Unicef, UNESCO, World Economic Forum and Amsterdam Airport.

Additional Notes About the Visualizations

  • More information about potentially habitable worlds is available in the Habitable Exoplanets Catalog.
  • The PHL's Exoplanet Catalog has all the data from the visualizations.
  • The shown Earth Similarity Index tab is only based on observed quantities (i.e. stellar flux, and mass or radius).
  • The expected Composition and Atmosphere tab is based on modeled quantities since there are not actual measurements of the bulk composition and atmosphere properties for most exoplanets. This gives a general sense of those planets that are more likely to have a composition and atmosphere suitable for life (i.e. potential for surface liquid water).
  • A general mass-radius relationship was used to visualize together data from both transit and RV measurements.
  • For additional comments on the science data or visualization contact Prof. Abel Méndez.

Alien Worlds Around Alien Stars

posted Sep 16, 2015, 5:18 AM by Abel Mendez   [ updated Sep 16, 2015, 6:02 AM ]

New collaboration to study star-planet magnetic interactions.

Caption: Artistic representation of the magnetic field (red lines) around a potentially habitable world (Credit: PHL @ UPR Arecibo).

The Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo (PHL @ UPR Arecibo) is starting a new collaboration with Rice University and the Arecibo Observatory to study the magnetic interactions of stars and planets, focusing on potentially habitable worlds.

There are up to thirty potentially habitable worlds out of the nearly two thousand known confirmed planets around other stars (exoplanets). We understand that these worlds might have the right size and distance from their star to sustain surface liquid water, but little else is known.

Exoplanets similar to Earth could end up dry and unsuitable for life depending on how they evolve with their star. Therefore, it is necessary to understand the long-term interactions between planets and their star to recognize and characterize habitable worlds.

The Sun produces the energy to maintain a temperate environment and sustain life on Earth. It also emits harmful energy that could strip our atmosphere or damage life at a cellular level, but Earth’s magnetic field gives us some protection from the damaging effects of the Sun.

Scientists keep monitoring and understanding how our Sun and Earth interact, maintaining a global habitable environment. However, many stars are much more active than the Sun or suitable planets might lack the protection of a magnetic field, thus limiting their potential for life.

The study as part of this collaboration will model star and planet magnetic interactions using the Sun’s interactions with the Earth, Saturn and Jupiter as calibration points. Such models might help not only to better understand the diversity of habitable worlds out there but also to create new strategies for their search and detection.

The PHL will contribute with its expertise on habitable exoplanets, the creation of educational visualizations, and a summer astronomy academy. The academy will be held at the Integrated Science Multi-use Laboratory (ISMuL) of the UPR Arecibo, and the Arecibo Observatory.

This five-years collaboration, Modeling the Magnetic Interactions between Stars and Planets, is led by members of the Laboratory for Space and Astrophysical Plasmas from the Rice Space Institute and funded by a NSF INSPIRE grant.


— Spanish Version —

Mundos Extraños Alrededor de Estrellas Extrañas
Nueva colaboración para el estudio de las interacciones magnéticas entre estrellas y planetas.

El Laboratorio de Habitabilidad Planetaria de la Universidad de Puerto Rico en Arecibo (PHL @ UPR Arecibo) está comenzando una nueva colaboración con la Universidad de Rice y el Observatorio de Arecibo para estudiar las interacciones de las estrellas con los planetas, centrándose en mundos potencialmente habitables.

Ya hay un máximo de treinta mundos potencialmente habitables entre los casi dos mil planetas conocidos y confirmados alrededor de otras estrellas (exoplanetas). Entendemos que estos mundos pueden tener el tamaño y la distancia a su estrella para mantener agua líquida en su superficie, pero muy poco más se sabe.

Los exoplanetas similares a la Tierra podrían terminar áridos y no aptos para la vida dependiendo de la evolución con su estrella. Por lo tanto, es necesario entender las interacciones a largo plazo entre los planetas y sus estrellas para reconocer y caracterizar mundos habitables.

El Sol produce la energía necesaria para mantener un ambiente templado y sostener la vida en la Tierra. También emite energía dañina que nos podría despojar de nuestra atmósfera o dañar la vida a nivel celular, pero el campo magnético de la Tierra nos da una cierta protección contra los efectos dañinos del Sol.

Los científicos monitorean y estudian cómo el Sol y la Tierra interactúan, manteniendo un ambiente habitable globalmente. Sin embargo, muchas estrellas son mucho más activas que el Sol o los planetas adecuados pudieran carecer de la protección de un campo magnético, lo que limita su potencial para la vida.

El estudio en esta colaboración pretende modelar las interacciones magnéticas de las estrellas y planetas utilizando las interacciones del Sol con la Tierra, Saturno y Júpiter como puntos de calibración. Tales modelos pueden ayudar no sólo para comprender mejor la diversidad de mundos habitables en el universo, sino también para crear nuevas estrategias para su búsqueda y detección.

El PHL contribuirá en este estudio con su experiencia en exoplanetas habitables, creando visualizaciones educativos y ofreciendo una academia de astronomía en verano. La academia se llevará a cabo en el Laboratorio de Multiusos de Ciencias Integradas (ISMuL) de la UPR de Arecibo y el Observatorio de Arecibo.

Este estudio de cinco años, Modelando las Interacciones Magnéticas entre Estrellas y Planetas, está liderado por miembros del Laboratorio de Plasmas Espaciales y Astrofísicos del Instituto Espacial Rice y es financiado por una subvención de la NSF INSPIRE.


1-10 of 43