NASA Astronomy Picture of the Day 24 March 2023: Comet ZTF and the stars of Milky Way

Comets are of great interest to scientists as they are remnants of the early Solar System, providing valuable information about its composition and conditions. One of these is the Rare Green Comet ZTF which made its extremely rare approach to Earth just last month. The tech that discovered Comet ZTF was the wide-field survey camera at the Zwicky Transient Facility in 2022 in March last year.

While comets often pass close to Earth, Comet C/2022 E3 (ZTF) is particularly noteworthy because it has a 50000-year orbit, meaning the last time it came close to Earth was almost 50000 years ago during the Upper Paleolithic period when Neanderthals were still present on Earth.

Today’s NASA Astronomy Picture of the Day is a picture of Comet ZTF fading away in the sky. According to NASA, it is now 13.3 light-minutes away from Earth and will go on its way before it makes another approach with Earth 50000 years into the future. The comet can be seen alongside stars of the Milky Way Galaxy in the towards the constellation Eridanus.

The picture was captured by astronomer Rolando Ligustri.

NASA’s description of the picture

Former darling of the northern sky Comet C/2022E3 (ZTF) has faded. During its closest approach to our fair planet in early February Comet ZTF was a mere 2.3 light-minutes distant. Then known as the green comet, this visitor from the remote Oort Cloud is now nearly 13.3 light-minutes away. In this deep image, composed of exposures captured on March 21, the comet still sports a broad, whitish dust tail and greenish tinted coma though. Not far on the sky from Orion’s bright star Rigel, Comet ZTF shares the field of view with faint, dusty nebulae and distant background galaxies.

The telephoto frame is crowded with Milky Way stars toward the constellation Eridanus. The influence of Jupiter’s gravity on the comet’s orbit as ZTF headed for the inner solar system, may have set the comet on an outbound journey, never to return.