Comet C/2022 E3 (ZTF) is in danger of having a shock. 50,000 years ago, the last time she visited us, we shared Europe with another human species, the Neanderthals. For her real big comeback, in the era of skyscrapers and global warming, she has however chosen February 1, the date on which she will be closest to Earth.
Here is comet C/2022 E3 (ZTF), which could become visible to the naked eye (but a priori weakly) by the end of the week and pass closest to Earth in early February. In the meantime, admire his hair and his two tails in this image of JF Hernandez https://t.co/pqbcyRIYdLpic.twitter.com/bUP3WqO4CA
— Eric Lagadec (@EricLagadec) January 9, 2023
In reality, it is already possible to admire it, as it reaches perihelion on Thursday, January 12, the point in its orbit closest to the Sun.
More precisely, it will increase to 0.28 astronomical units (a length corresponding to the approximate distance between the Earth and the Sun) of our planet, or 43 million kilometers. By comparison, the Moon is 384,400 kilometers from Earth.
A comet visible to the naked eye
This “visitor” from space will then normally reach a magnitude between 5.1 and 7.35, which will make it visible to the naked eye. However, the spectacle will be even more mesmerizing with a telescope or astronomical binoculars.
In order to see the comet, it is necessary to find a patch of dark sky. To locate it, it is possible to use a stellar observation application such as Star Walk 2 or Sky Tonight. In these, just type the name of the comet (C/2022 E3 ZTF) before being guided.
For the old-schoolers and the more seasoned, there are also thematic websites, such as theskylive.com, which allow you to unearth the star. It will be visible in the constellation Giraffe.
A star from the Oort cloud
Specialists recommend using shifted vision. This technique consists of looking slightly next to the star, which allows you to see much better in the night sky. Like all comets, the brightness of C/2022 E3 (ZTF) is difficult to predict: it may suddenly darken.
This comet owes its name to its date of discovery, March 2, 2022. The acronym ZTF designates the Zwicky Transient Facility, the Californian observatory at the origin of the find.
Comets can come from two places: the Kuiper belt, located 150 astronomical units from the Sun, or the Oort cloud, whose boundaries are blurred and which is between 20,000 and 30,000 astronomical units from Earth.
Comet Hailey, the least shy
C/2022 E3 (ZTF) comes from this second focus. It is a star of ice and dust whose diameter reaches 1 kilometer. Comets owe their name (“hairy star” in Greek) to their orbit which brings them closer to the Sun. As they approach the star, they eject matter in the form of a tail.
The Japanese prefer the name “star-brooms” to designate these small celestial objects. They rarely approach Earth. The least shy of them, Halley’s Comet, only visits us once every 76 years.