The Bright Green Comet 21P Can Be Seen Using Only A Pair Of Binoculars

Monday, 10 September 2018 - 12:52PM
Monday, 10 September 2018 - 12:52PM
The Bright Green Comet 21P Can Be Seen Using Only A Pair Of Binoculars
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Pixabay Composite
Did you see that?

According to EarthSky, comet 21P/Giacobini-Zinner made its closest approach to our planet in over seven decades. The comet was expected to pass us at a distance of only 36 million miles, which is far enough to not be a threat, but still close enough for stargazers to get really excited. If you were out and about around 2:30 AM EST with your trusty binoculars or a small telescope, then you may have caught a glimpse of this bright green comet zipping overhead.



Comet 21P has been right on the edge of almost being visible to the naked eye this month with a visible magnitude around 6.5-7. Its close approach was even more special because it coincided with its perihelion, which is the point where an orbiting object is closest to the sun. Comet 21P is only about a mile in diameter, but EarthSky explains that the heat from the sun has caused the comet to develop a "cometary atmosphere" that is twice the diameter of Jupiter at around 180,000 miles. The huge cometary atmosphere, or coma, is what you would see if you viewed the comet through a telescope. The bright green color suggests that there are cyanogen and diatomic carbon gases in Comet 21P's coma (which glow in sunlight). 

Comet 21P is traveling at 50,555MPH relative to our planet. For comparison's sake, that's nearly three times faster than the International Space Station and the Hubble Telescope. Unfortunately, if you missed it this time around you'll have to wait until September 18, 2058, for its next-closest approach. This December, however, the comet 46P/Wirtanen is expected to reach a visible magnitude in the range that our naked eyes can see it, so stay tuned for more about that in the coming months.
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