Two comets are getting very close to the Earth, and this is excellent news, first, because they’re not on a collision trajectory with us, and, secondly, because they will cross the sky close enough to be seen even with a small telescope. We’re talking about Comet 21P/Giacobini-Zinner (Green Comet), which visits us this month, and comet Wirtanen, which could be seen with the naked eye in December this year.
The so-called Green Comet (Comet 21P) now travels towards the Earth and the Sun at about 23 kilometers per second and will fly by our planet between September 8th and 10th. It will pass at approximately 58 million kilometers which is vast, comparable to the distance between Mars and us.
To see the Comet 21P, you will need a small telescope aimed between the constellations Camelopardalis, Perseus, and Auriga. On September 10th, at night, the comet will pass very close to Messier 37, the brightest open cluster in the Auriga constellation.
Comet 21P was nicknamed the Green Comet because of its greenish glow under the sunlight
According to the Northolt Branch Observatory in London, the coma that surrounds the nucleus of the comet is 290,000 kilometers, which is twice the diameter of the largest planet in the solar system, Jupiter. Its green color indicates that it is composed of cyanogen and diatomic carbon, two gases that glow green when illuminated by the sun.
During its orbit around the sun, comet 21P produces some debris causing the rain of Draconids meteor shower, which is also called Giacobinids. They will be visible starting on October 7th and will coincide with the new moon phase, so the phenomenon will be visible. Next time comet 21P will visit us will be in 2058.
On the other hand, the comet Wirtanen will be able to be seen in December and very possibly without needing any equipment.