Its last visit was 50,000 years ago.
The comet "C/2022 E3 (ZTF)", coming from the confines of the solar system, will pass close to the Sun this week and could be visible to the naked eye at the end of January.
It was discovered recently.
In March 2022, the Zwicky Transient Facility (ZTF) astronomical sky survey program noticed a small, rocky, icy body, estimated to be around 1 km in diameter, thanks to the Samuel-Oschin Telescope at Palomar Observatory, California.
Detected as it passed through Jupiter's orbit, the comet is currently heading towards the Sun and will reach its perihelion, or its closest point to the Sun, on January 12, according to astronomers' calculations. .
The celestial object will then be “10% further” from the Sun than the Earth is (about 150 million km), specifies Nicolas Biver, of the Paris-PSL Observatory.
When a comet approaches the Sun, the ice contained in its nucleus sublimates and lets out a long trail of dust reflecting the light of the Sun.
It is this shiny hair that we will be able to observe from Earth, as “C/2022 E3 (ZTF)” comes towards us.
The comet will reach the peak of its brightness "when it is closest to Earth", explains Thomas Prince, professor of physics at the California Institute of Technology, who works for ZTF.
The phenomenon will however be less spectacular than during the passage of its congeners Hale-Bopp (1997) or Neowise (2020), much larger.
The star will be easily spotted with a good pair of binoculars, and perhaps even with the naked eye during part of the night, under a sky without too much Moon and free from light pollution.
"We can have a good surprise and see an object twice as bright as expected," hopes astrophysicist Nicolas Biver.
Coming from the Oort cloud
The best viewing window should be the weekend of January 21-22 and the week after.
During this period, the comet will pass between the constellations of Ursa Minor and Ursa Major.
Before diving into the southern hemisphere and heading back to the confines of the solar system, its probable cradle.
According to current models, comets come from two reservoirs: the Kuiper belt, beyond the orbit of Neptune, or the Oort cloud, a vast theoretical zone located up to one light-year from the Sun, at the limit of its gravity field.
"According to the inclination of the plane of its orbit, it would be a long-period comet originating initially from the Oort cloud", according to Nicolas Biver.
This is not the first time the frozen visitor has passed close to the Sun: a previous trip had already propelled him towards our lands, approximately… 50,000 years ago.
Better understand the composition of comets
The comet then went back in the other direction, but did not go as far as the Oort cloud.
This time, it will probably end up being "permanently ejected from the solar system".
His final visit will be an opportunity for scientists to understand a little more about the composition of comets, in particular thanks to observations by the James Webb Space Telescope.
“We will observe it from every angle.
It's not the comet of the century, but we're happy to be able to observe comets like these every one or two years, because we consider them to be vestiges of the formation of the solar system,” explains Nicolas Biver.
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This “rare visitor” will bring “information about the inhabitants of our solar system far beyond the most distant planets”, adds Thomas Prince.