A strange green comet that has not passed near Earth since the time of primitive man has returned to appear in the sky in preparation for approaching the planet next week.
The green comet known as C / 2022 E3 (ZTF) was discovered last March by astronomers in California, and its orbit around the sun was calculated once every 50,000 years, which means that the last time it passed our home planet was in the Stone Age.
The comet, which comes from the Oort cloud, will be closest to Earth on Wednesday and Thursday next week when it passes within 2.5 light minutes, or only 27 million miles, from our planet.
Comets are balls of dust and ice that swing around the sun in giant elliptical orbits.
As they get closer to the sun, the objects heat up, which turns surface ice into gas and removes dust from it.
This leads to the formation of the cloud that surrounds the comet’s solid nucleus.
Already captured images of comet C/2022 E3 reveal a subtle green glow that is believed to originate from the presence of diatomic carbon in the head of the comet.
Green light is emitted by the molecule when ultraviolet rays penetrate it in solar radiation.
Since mid-January, the comet has become easy to spot with a telescope or binoculars, and is visible in the northern hemisphere.
