This month sees an exciting new object grace our skies. Comet C/2020 F3 NEOWISE, more commonly known as Comet NEOWISE, was discovered by the NEOWISE space telescope on the 27th March 2020. But don’t worry, you don’t need to launch yourself into space to see it!
Comets are notoriously unpredictable, and it’s often difficult for astronomers to know whether a comet will be visible in our skies. This is especially true for newly discovered comets like this one. There was some trepidation around the comet: nobody could be sure that it would be a worthwhile object for amateur astronomers. But over the last weekend, the news began to spread that Comet NEOWISE was bright enough to see with the naked eye!
What’s the comet like?
NASA’s NEOWISE telescope used to be the Wide-field Infrared Survey Explorer (WISE), but in 2013, it began a dedicated search for NEOs, or Near Earth Objects. Hence it is now the Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope! Since then, the telescope has discovered 15 new comets, including Comet NEOWISE.
Comets like this one tend to have extremely long orbital periods, so we don’t often discover them until they get close to the Earth. Comet NEOWISE takes 4,300 years to approach the Sun from the outer reaches of the solar system. However, it takes 6,500 years to go the other way. This is because of a certain large planet with lots of gravity: Jupiter! Jupiter is so large that its gravity can affect the orbits of smaller bodies like comets.
This comet is what’s known as a long-period comet. Long-period comets have orbital periods much greater than 200 years. They are thought to originate from the Oort Cloud, a sparsely-populated area at the edge of the solar system. Objects in this area can be gravitationally affected by things outside of our solar system, like the Sun moving past another star, or the shockwave of a supernova. This leads to them being dislodged, forcing them into highly elliptical orbits that bring them further into the solar system.
How can you see it?
Comet NEOWISE reached perihelion, its closest point to the Sun on the 3rd July. It is slowly moving closer to the Earth, where it will make its closest approach on the 23rd. It will pass by us at a distance of 0.69 AU (103 million km): that’s about 400 times further away than the Moon! That might seem far, but it is in fact relatively close for a comet.
Although this comet is technically a naked eye object, it will still be quite challenging to observe. It appears in the northern sky, but does not rise very high, so a clear horizon is a must. In addition, Comet NEOWISE is not a point-like object, appearing slightly fuzzy. Along with the bright summer sky, this makes it appear fainter than it really is. View it with binoculars or a telescope for best observing!
The 7th July is the best time for viewing Comet NEOWISE. You’ll have to stay up late (or possibly get up early) to catch this phenomenon, as it will only be visible around midnight and into the early hours of the morning. Right now it’s in the constellation of Auriga, but it moves across the sky during the month, through the constellations of Lynx, Ursa Major and Coma Berenices.
Of course, we can’t predict the future of the comet accurately. It’s shining brightly right now, but it could break apart or fizzle out like previous comets of the year. So make sure to catch this cosmic visitor while you can!