NASA eClips: Transits A 'transit' occurs whenever one object
moves in front of another object as viewed from your particular
location in space. We observe this phenomenon thousands of times
every day because we live in a 3-dimensional world that is
crowded by many different kinds of objects as we move past them.
In astronomy, transits are actually rather rare. The most
dramatic ones we hear about involve the moon passing in front of
the sun. because the moon and sun appear to be about the same
size, we call these transits 'eclipses'. On rare occasions, the
planet's Mercury and Venus can be seen as small 'dots' passing
across the face of the sun. The light from the sun actually dims
by a small amount when this happens, but only astronomers can
measure this dimming. As it turns out, we can measure this
dimming of distant stars and use it to discover planets orbiting
them. The NASA Kepler mission has detected over 700 of these
'transiting exoplanets' since 2009 in a study of over 150,000
stars. The image to the