Terminator

Terminator - A boundary marking the apparent intersection between day and night on a planet or moon.

The image shows a terminator on the Moon (see arrow). The International Space Station can be seen as a small white dot just to the left of the arrow, on the night side of the terminator.

https://apod.nasa.gov/apod/ap150427.html

Author: Amber Crawford, UCF Undergraduate 2017
Editor: Patrick Joiner, UCF Interdisciplinary Studies, Class of 2018
Senior Editor: M.M. Montgomery, Ph.D, UCF Physics