visible for the first time since the stone ages: the green comet

Hurtling through the cosmos at an unimaginable speed, the ZTF comet, known for its bright green colour, will be visible to stargazers on February 1st, 2023 for the first time in 50,000 years.

Bryce Bolin and Frank Masci, astronomers at the Zwicky Transient Facility in California, first discovered this comet in March of 2022. Analysis of its trajectory uncovered when it was last this near to us; revealing that humans had not seen it since the stone age.

To stargazers and astronomers in the northern hemisphere, the comet will be most visible on the night of February 1st, 2023. After this, it will dim, and be visible to those in the southern hemisphere. Here's a sky chart displaying the location of the comet at its closest point to Earth.

More on Comets

NASA explains comets as 'cosmic snowballs of gases, rock and dust that orbit the sun'. There are currently 3,743 comets orbiting our sun, some of which have a far shorter orbit than ZTF. Those we see more frequently usually come from the Kuiper Belt, a region of icy bodies occupying the region between the orbits of Neptune and Pluto. These are known as short-period comets, which take less than 200 years to complete a single orbit.

ZTF, however, is a long-period comet, which may take from 200 years up to a billion to complete an orbit. As we understand them, comets like ZTF originate in a orbital layer much more distant than the Kuiper belt. This layer is known as the Oort Cloud, found far outside the orbit of Pluto.

This long orbit means that viewing this comet is a once-in-a-lifetime opportunity; literally!

Now you know more about comets, and more about this one specifically, make sure you look up at the night sky on February 1st to catch ZTF before it disappears for another 50,000.