Rare green comet revisits Earth after 50,000 years

A rare green comet, a unique traveler, is revisiting our solar system these days after 50,000 earth years when people still lived in caves.

Astrophysicist Dr. Stelios Tsangarides told CNA that comet C/2022 E3 (ZTF) will reach its closest distance to Earth on February 1, 2023, when it will be at a distance of 42 million km from our planet. In dark areas, it will be visible as a faint, cloudy object.

The comet was discovered on March 3, 2022, by astronomers Bryce Bolin and Frank Masci (Zwicky Transient Facility, USA), when it was still on its way to the inner solar system. Almost a year later, the comet has already orbited the Sun and will soon pass close to the Earth.

What makes C/2022 E3 interesting is its greenish color, he said, and explained that the color is caused by the presence of molecular carbon (C2) on its surface. The comet, Tsangarides noted, is also interesting because as a long-period comet, its orbit around the Sun may take about 50,000 Earth years.

"This means that the last time it was in our neighborhood - if there was a previous time - people were still living in caves and not even oral historical records have survived - the oldest of which, the songs of the Australian aborigines, are estimated to be around 40,000 years old," he told CNA.

Amazing. Here's a great animated capture of Comet C/2022 E3 ZTF's recent tail disconnection event (along with lots of #Starlink streaks), courtesy of @Komet123Jager - https://t.co/VWeFpDf4U2 pic.twitter.com/EP6lY9kg9s

— Dave Dickinson (@Astroguyz) January 19, 2023

Tsangarides said “it will reach its closest distance to Earth on February 1, 2023, when it will be at a distance of 42 million km from our planet. It will become visible to the naked eye, but at the limits of human vision, as a faint, nebulous object near the north celestial pole in the constellation Camelopardalis."

For those who would like to see it with the naked eye, its dim appearance and the fact that the Moon will be more than half - February 5 is the full moon - will make it invisible from the cities, with its intense light pollution, he noted.

“It may only be visible from the areas of our island with the darkest skies", Tsangarides concluded.