‘Green comet’ appearing close to Earth after 50,000 years

Subject :Science and Technology

Section: Space Technology

Context:

The comet termed the C/2022 E3 (ZTF), is named to refer to those who first spotted it – astronomers using the wide-field survey camera at the Zwicky Transient Facility (ZTF) in the US.

Comets:

Comets are frozen rocky or gas-filled objects that are remnants of the formation of the solar system.
Due to their composition, characteristics and the path they move in, they tend to leave a light behind them.

Where do comets come from?

The orbit indicates it comes from the edge of our solar system, a distant reservoir of comets known as the Oort cloud.
The Oort cloud is thought to be a big, spherical region of outer space enveloping our sun, consisting of innumerable small objects, such as comets and asteroids.
NASA terms it “the most distant region of our solar system” and “Home of the Comets”.
The green comet could be at a distance of 2.5 light minutes from Earth, meaning a “mere” 27 million miles.

What is the ‘green comet’?

Here, the comet itself is green (called the head of the comet) and emits a whitish light behind it (often called the tail of the comet).
Comets have often been seen giving out blue or whiteish light, or even green.
In this case, the green glow is thought to arise from the presence of diatomic carbon – pairs of carbon atoms that are bound together – in the head of the comet.
The molecule emits green light when excited by the ultraviolet rays in solar radiation.

How rare is the green comet?

They come under the category of long-period comets, which take more than 200 years to orbit the sun.
As they have a highly elliptical orbit, these comets will head back to the Oort cloud and will appear again after 50,000 years.

Why do comets leave a trail of light behind them?

Just like other bodies in space, comets also have orbits. They are sometimes pulled in close to the sun because of the sun’s gravity acting on them.
As they orbit near the Sun they heat up and spew gases and dust into a glowing head that can be larger than a planet.
Due to their orbit near the sun, the remains of dust following this burnup, from a distance, look like a trail of light to humans on Earth.