A recently discovered green-tailed comet will be visible to the naked eye for the first time in 50,000 years this Thursday (12/01) and in the coming weeks.
Called C/2022 E3 (ZTF), it is a small icy rocky body, just 1 km in diameter, and was discovered in March 2022 by the Zwicky Transient Facility (ZTF) program, which operates the Samuel-Oschin telescope at the Palomar Observatory, California.
It was initially detected as it crossed the orbit of Jupiter and will reach its perihelion (closest point to the Sun) this Thursday, when it will be at a distance of 166 million km from the star.
The closest point to Earth, at a distance of 42 million km, will be reached on February 1, according to astronomers who studied the comet’s trajectory.
why green?
A comet only gains a tail as it approaches the Sun.
The ice in its core goes directly from solid to gaseous state, releasing gas and dust, which creates a cloud around it, called an ice cloud. coma or “hair” – reflecting sunlight. In this comet, due to its composition, it is very green.
The closer you get to the Sun, these particles spread out for thousands of kilometers, “blown” by the solar wind. There’s the long tail, which disappears as the comet moves away from our star. A of C/2022 E3 (ZTF) is bluish and triple.
It is this trail that can be seen, initially in the northern hemisphere, as the comet approaches our planet. With the help of telescopes, it is already recorded in detail.
Most likely, to the naked eye, the comet will look like a blurry star. The unusual green color is probably due to the presence of diatomic carbon in the canopy.
It will shine in all its glory as it approaches Earth, which is expected to happen on February 1st.
Even so, it will be less spectacular than the much larger comets Hale-Bopp (1997) or Neowise (2020).
Best observation period
With good binoculars, or even with the naked eye, the comet can be seen at night, provided the sky is clear and there is no light pollution.
In the northern hemisphere, the best observation period will be the weekend of January 21 and 22 and the following week, when it will pass through the constellations of Ursa Minor and Ursa Major.
Thereafter, it can be seen in the Southern Hemisphere, having its best visibility in early February, before returning to the outer reaches of the Solar System.
Since Neanderthal times
Astronomers calculate that the origin of the green comet is the Oort Cloud, a huge spherical structure of comets located almost 1 light-year away from the Sun, at the limit of its gravitational field.
All long-period comets, such as C/2022 E3 (ZTF), are believed to originate in the Oort cloud, while short-period comets (less than 200 years old) originate in the Kuiper belt.
C/2022 E3 (ZTF) already visited the inner Solar System about 50,000 years ago, in the Upper Paleolithic, when it also passed close to the Earth, then inhabited by Neanderthals and early Omo sapiens.
Some astronomers say it will be back in another 50,000 years, while others say there’s a good chance it will be expelled from the Solar System for good before then.
The orbit of this comet around the Sun is so long that it goes beyond the boundaries of the Solar System. This explains why it takes so long to get back.
Scientists intend to observe it to learn a little more about the composition of comets, especially with the help of the powerful James Webb telescope.
“We will observe it from all sides. It is not the comet of the century, but we are happy to be able to observe comets like this every one or two years, because we consider them vestiges of the formation of the Solar System,” explained scientist Nicolas Biver, of the Paris-PSL Observatory.
* With information from Marcella Duarte, from Uol Tilt
