Here are a few transit simulations of Earth-like planets with and without moons (Figures 1-3) including Avatar's Pandora (Figure 4). All simulations assume long cadence observations (every 29.4 minutes) by the Kepler telescope and are stellar limb corrected. They were done with SPHERE-SIM, a software tool of the SPHERE Project to simulate complex transit events for statistical studies, such as those caused by multiple stars/planets, moons, and rings.
![]() Figure 1. Animated simulation of the transit of Earth around the Sun as it will appear from far away to a Kepler-like telescope. The solid line is the expected stellar flux and the dots are the observed values, assuming a 40 ppm combined noise. Time is with respect of mid-transit. This simulation does not include the Moon. A MP4 movie version of this animation is also available.
![]() ![]() Figure 2. Simulated stellar flux of the transit around the Sun of Earth alone (top) and Earth with the Moon (bottom) as it will appear from far away to a Kepler-like telescope. The blue curve is the expected flux and the red dots the observed flux, assuming a combined noise of 60 ppm. The presence of the Moon (at its maximum separation of 60 Earth radii) causes a small dent (starting at -10 hours) in the expected flux but this is not apparent in the observed flux.
![]() ![]() Figure 3. Simulated stellar flux of the transit of Kepler-22 b alone (top) and with a hypothetical one third size moon (bottom). The blue curve is the expected flux and the red dots the observed flux, assuming a combined noise of 60 ppm. Even that the hypothetical moon (located at 20 Kepler-22 b radii) is a little larger than Mars (0.6 Earth radii) its presence is not easily notable in the observed flux.
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