An exotic comet is causing excitement this week. We take a look at what we know about the unusual celestial object, and how best to catch a glimpse.

This particular comet is called C/2022 E3 (ZTF) and was discovered by astronomers in March 2022 at the Zwicky Transient Facility in California.

It has been nicknamed “the green comet” because of its verdant glow, and is thought to have come from the Oort cloud – a collection of icy bodies that are believed to exist in the farthest-flung part of the solar system.

While some comets are relatively frequent visitors – Halley’s comet turns up every 76 years on average – C/2022 E3 (ZTF) orbits the sun every 50,000 years.

In other words, the last time it could have been visible from Earth was in the stone age, when not just modern humans, but Neanderthals, too, may have directed their gaze starwards.

The green glow isn’t unique to this comet, although it is an interesting feature.

The green glow isn’t unique to this comet, although it is an interesting feature.

The phenomenon is thought to arise from an interaction between light from the sun and diatomic carbon.

The phenomenon is thought to arise from an interaction between light from the sun and diatomic carbon.

Diatomic carbon is an unstable, gaseous form of the element in which carbon atoms are bonded together in pairs.