Want to see a comet whizzing by Earth? A great chance to catch one of these celestial visitors is overnight tonight, when Comet 21P/Giacobini-Zinner will be best visible in binoculars or a telescope. The comet, also known as "21P," will make its closest approach to Earth at around 2:30 a.m. EDT Monday (630 GMT). The bright-green comet should reach a visual magnitude of 6.5 to 7, according to EarthSky.org. This makes 21P almost bright enough to see with the naked eye — but not quite. [Bright Comets of 2018: When, Where and How to See Them] To find Comet 21P...
