Science‎ > ‎


After NASA's EPOXI mission observed a transit of the Moon across Earth's disk at visible and NIR wavelengths, I started to wonder how important the light from an unresolved companion could be when trying to observe and characterize an exoplanet. To address this question, I used models to study how a distant observer would see the Earth-Moon system, and got some exciting results.  It turns out that, depending on the wavelength and phase, the Moon can actually outshine Earth by a factor of almost 10 (see figure below).

This work is described in Robinson (2011), wherein I developed a simple, semi-analytic model for simulating the thermal spectrum of a slowly-rotating, airless moon. The IDL code which implements that model can be found here.  It's fairly straightforward - you input a phase angle, and out comes a spectrum.  If you use this tool, please cite the aforementioned paper.

In Robinson et al. (2014), we analyzed and modeled observations of Earth from the Lunar CRatering Observation and Sensing Satellite (LCROSS) at wavelengths from the ultraviolet to the infrared.  Over the course of this work, we noticed problems with the calibration of the LCROSS visible spectrometer (VSP).  So, using models of the Moon's reflectivity, we derived a wavelength-dependent calibration correction factor that can be applied to LCROSS VSP data taken from NASA's PDS.  A plot of this correction factor is shown below, and a data file is here.