An exotic green comet that has not passed Earth since the time of the Neanderthals (50,000 years ago) has reappeared in the sky ready for its closest approach to the planet tonight and tomorrow evening, February 2.
Discovered last March 2022 by astronomers at the Zwicky Transient Facility at the Palomar Observatory in California, USA, comet C/2022 E3 (ZTF) was calculated to orbit the sun every 50,000 years, meaning it last tore past our home planet during the Stone Age.
The comet, which comes from the Oort Cloud at the edge of the solar system, will come closest to Earth tonight and tomorrow evening, when it shoots past the planet at a distance of 2.5 light minutes – a mere 27m miles.
Images already taken of what space enthusiasts call “Green Goblin,” reveal a subtle green glow that 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.
While the best views may be seen tonight and tomorrow, by the middle of the month the comet will have dimmed again and slipped from view as it hurtles back out into the solar system on its return trip to the Oort Cloud.