Context: The recently discovered comet called C/2020 F3, also known as NEOWISE after the NASA telescope that discovered it, will make its closest approach to the Earth on July 22

About C/2020 F3 Neowise:

  • The comet takes 6,800 years to complete one lap around its orbit, and will be at a distance of 64 million miles while crossing Earth’s outside orbit.
  • On July 3, the comet was closest to the sun at 43 million km. On this day, the comet cruised inside Mercury’s orbit which is the closest planet to the Sun.
  • Due to its proximity to the sun, its outer layer was released creating an atmosphere called coma – of gas and dust from its icy surface.

About Comets:

  • Comets or “dirty snowballs” are mostly made of dust, rocks and ice, the remnants from when the solar system was formed over 4.6 billion years ago. 
  • Comets may be occasionally pushed into orbits closer to the sun and the Earth’s neighborhood due to forces of gravity of other planets.
    • Each time a comet passes the sun, it loses some of its material and it will eventually disappear completely as a result.Many comets don’t survive their close proximity to the sun.
  • Comets do not have light of their own and what humans are able to see from Earth is the reflection of the sun’s light off the comet as well as the energy released by the gas molecules after it is absorbed from the sun.
  • Comets can range in their width from a few miles to tens of miles wide. 
  • The debris forms a tail that can stretch out to millions of miles. 

Short period and predictable comets:

  • Predictable: The appearance of some comets, like those that take less than 200 years to orbit around the sun is predictable since they have passed by before.
    • One of the most famous short-period comets is called Halley’s Comet that reappears every 76 years. Halley’s will be sighted next in 2062.
  • Location: They can be found in the Kuiper belt, where many comets orbit the sun in the realm of Pluto, occasionally getting pushed into orbits that bring them closer to the sun. 
    • The Kuiper Belt is a doughnut-shaped ring of icy objects around the Sun, extending just beyond the orbit of Neptune from about 30 to 55 AU.
    • The first mission to explore the Kuiper Belt is New Horizons. It flew past Pluto in 2015 and is on its way to explore another Kuiper Belt world

The less-predictable comets:

  • Comets in this cloud can take as long as 30 million years to complete one rotation around the sun.
  • Location: They can be found in the Oort cloud that is about 100,000 AU from the sun, or 100,000 times the distance between the Earth and the sun.