Download Video  Video Information  Subscribe to Series   Distant
Planet Flaunts its Light  This artist's animation shows a close-
up view of a distant giant planet passing behind its star as a
regular part of its orbit. By studying "secondary eclipses" like
this in infrared light, astronomers can capture and study the
direct light of known extrasolar planets. Though they cannot
actually distinguish the planet from its star, they can detect
changes in the system's total light.  Why a secondary eclipse?
When a planet transits, or passes in front of, its star, it
partially blocks the light of the star. When the planet swings
around behind the star, the star completely blocks its light.
This drop in total light can be measured to determine the amount
of light coming from just the planet.  Why infrared? In visible
light, the glare of a star overwhelms its planetary companion
and the little light the planet reflects. In infrared, a star
shines less brightly, and its planet gives off its own internal
light, or heat r