The Transiting Earth

From spectra collected during the August 2008 lunar eclipse, astronomers have been able to investigate the in-transit signature of the Earth-Sun system as would be observed from outside the solar system.
They found that the refraction of sunlight as it passes through a planetary atmosphere similar to the Earth's contributes prominently to the in-transit transmission spectrum.
This research has important implications for future attempts to characterise the atmospheres of Earth-like extrasolar planets, especially those in similar long-period orbits.