Nadir
by Dominic Ford, Editor
Last updated: 23 Feb 2019
The nadir is the point in the sky vertically straight below the observer's feet.
One of the most interesting planets in the solar system can be found there – the Earth. A telescope is not needed to see it since its disk is quite apparent to the naked eye, measuring 180° across. In fact, it is so large that it occults half of the sky.