Looking for a reduction in light due to a planet crossing in front of its star as seen by earth or the kepler space telescope is called a/an:

It is Transit. A Transit is "the phenomenon of at least one celestial body appearing to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point." Webster, Guy (June 10, 2014). "Mercury Passes in Front of the Sun, as Seen From Mars". NASA. Retrieved June 10, 2014.

Can you give me little more information

Answerdistinguish between the mercalli scale and the richter scale;