Why is Mercury so hot during the day and cold at night?

Question: Why is Mercury so hot during the day and cold at night?
- Keywords:
  cold,
  hot,
  mercury
Asked by nikhil to Gonzalo on 7 Nov 2017.
- Gonzalo Delgado-Pando answered on 7 Nov 2017:
  
  Very interesting question. This happens because Mercury has almost no atmosphere, a layer that protects some gases and the heat to go away. At night, all the heat from the day has gone away because there is almost nothing to keep the warmth there.

Question: Why is Mercury so hot during the day and cold at night?