Comet NEOWISE – July 22, 2020


If you’re in the Northern Hemisphere (and especially in the northern US) and haven’t had a chance yet to look up at the night sky, here’s your chance to see something really cool: a comet! Comet C/2020 F3 (otherwise known as NEOWISE) is visible in the night sky. If it’s really dark, you can see it with your unaided eye, but binoculars or a small telescope can help. Just after sunset, face northwest and find the Big Dipper. Sweep the sky below and to the left of the constellation until you spot it. What’s so special about this comet? It won’t be seen in our skies for another 6,800 years!
So, what is a comet? It can be thought of as a “snowy dirtball” containing dust, ice, carbon dioxide, methane and ammonia. The nucleus may contain a small rocky core. According to Emily Kramer, a science team co-investigator for NASA’s NEOWISE at NASA’s Jet Propulsion Laboratory, there are “about 13 million Olympic swimming pools of water” in Comet NEOWISE!
When passing close to the Sun, the comet warms up and begins to release its gases, forming a cloud called a coma. Radiation from the Sun pushes dust particles away from the coma, forming a dust tail, while charged particles from the Sun turn some of the comet’s gases into ions, forming an ion tail. The tails are shaped by the solar radiation and solar wind, so that they point away from the Sun. Comet NEOWISE is about 3 miles in diameter. Just how fast is it going? 40 miles….per SECOND (or, 144,000 miles per hour)!
Comets are primitive bodies left over from the formation of the Solar System. In fact, they were among the first solid bodies to form in the solar nebula from which our Sun and planets formed 4.6 billion years ago. So, by studying comets, scientists can learn more about the conditions of the early solar system and how the planets formed.

Image: “star” by Kiwi Tomlicensed under CC BY 2.0