A comet not seen since 50,000 years will be visible again in early 2023

A comet that last appeared in the night sky during the Ice Age will soon make a reappearance in February 2023, according to a NASA statement published last week.

Called the C/2022 E3 (ZTF) comet, it orbits the sun every 50,000 years. It will now pass within 26 million miles of Earth on February 1st, 2023.

It could also be visible to the naked eye in mid-to-late January. The comet can be seen using binoculars and low-level telescopes when the skies are clear.

A blue-green coma and a golden tail

Astronomers who have been tracking the E3 comet claim it has a blue-green coma and a golden tail. E3 was first discovered by astronomers Bryce Bolin and Frank Masci using the Zwicky Transient Facility (ZTF) survey on March 2nd 2022 and has since been photographed by astronomers at NASA.

“Since then the new long-period comet has brightened substantially and is now sweeping across the northern constellation Corona Borealis in predawn skies. It's still too dim to see without a telescope though. But this fine telescopic image from December 19 does show the comet's brighter greenish coma, short broad dust tail, and long faint ion tail stretching across a 2.5 degree wide field-of-view,” wrote NASA in its post about the famous comet.

“On a voyage through the inner Solar System comet 2022 E3 will be at perihelion, its closest to the Sun, in the new year on January 12 and at perigee, its closest to our fair planet, on February 1. The brightness of comets is notoriously unpredictable, but by then C/2022 E3 (ZTF) could become only just visible to the eye in dark night skies.”

Upon discovery, the comet had an apparent magnitude of 17.3 and was about 4.3 AU (640 million km) from the Sun.

Lighting up the sky

In February, it will be the first comet to light up the sky since the NEOWISE comet in the summer of 2020. NEOWISE was considered the brightest comet visible from the Northern Hemisphere since Hale-Bopp.

Anyone wishing to see the E3 comet should pick a dark spot and allow half an hour for the eyes to adjust.

Specialist smartphone apps and websites, such as Star Chart, Sky Safari, and SkyView, can also help to track the comet’s position in the sky.

“Comets are intrinsically highly unpredictable objects, since their brightness depends on the scattering of sunlight from dust particles in the comet’s coma and tail,” comet-tracking website In-The-Sky also noted.

“This dust is continually streaming away from the comet’s nucleus, and its density at any particular time is governed by the rate of sublimation of the ice in the comet’s nucleus, as it is heated by the sun’s rays. It also depends on the amount of dust that is mixed in with that ice. This is very difficult to predict in advance, and can be highly variable even between successive apparitions of the same comet.”