A mysterious comet is shooting through our solar system. Why are scientists so excited about 3I/Atlas? | Space
An object from the outside of our solar system rushes towards the sun at around 61 km (38 miles) per second.
Detected for the first time in July, this space visitor – known as 3i / Atlas – is only the third interstellar object known to have been observed, after ‘Oumamua in 2017 and 2i / Borisov in 2019.
Excitement has increased since the Hubble spatial telescope captured an image of the interstellar intruder, offering scientists a rare opportunity to analyze its size and chemical composition.
“We have never had an object like this to study before,” said Dr. Rebecca Allen, co-director of Swinburne’s Space Technology and Industry Institute.
What exactly is 3i / Atlas?
“We do not know exactly where it comes from, but it definitely came from outside the solar system,” said Dr. Laura Drisesen, radio-astronomer at the University of Sydney.
The name comes from “I” for Interstellar, “3” as the third object of this type detected, and atlas for the network of telescopes which identified it, called the latest asteroid alert system.
While some have speculated on an extraterrestrial foray, scientists say that 3i / Atlas is probably a comet. You may remember speculation on ‘Oumamua, which astronomers have checked for radio signals in case it was a foreign craft. This was not the case.
“There is no evidence to indicate [3I/Atlas] Being something other than a really funny space rock that came from outside the solar system, “said Disesen.” Which, to be honest, is pretty cool. “”
Why are scientists enthusiastic by the interstellar object?
In the Hubble image, 3i / Atlas looks a bit like a “blurred snowball”, says Allen. Its misty appearance is due to its “coma”, which forms when the surface of the comet is heated by the sun, Release dust and gas, and there are signs of a comet tail.
These chemical signatures – elements and molecules from the outside of our solar system – will become more visible, the closer it is, says Allen.
“We can use a tool called spectroscopy, and we can use light to understand exactly what this material is. Does this comet represent a solar system which had conditions very similar to ours, or is it something completely different? ”
The researchers have already used the Hubble image to estimate that the 3i / Atlas diameter is less than 5.6 km, and potentially as small as 320 meters.
Where is 3i / Atlas?
The spatial object travels at more than 200,000 km / h, says Allen.
“It will somehow cross the inner solar system – between March and the orbit of the earth – then it will fly in front of the sun.
“This is what we call a hyperbolic orbit. It is therefore not linked to gravitation in the sun. It moves far too fast, and therefore it flies on the other side of the solar system.”
Its interstellar origins make 3i / Atlas different from other comets that orbit in the solar system, such as the comet of Halley, explains Con Stoitsis, the comet and the meteor director of the astronomical Society of Victoria.
We expect him to make his approach closest to the sun between October and December – inside around 210m kilometers – then continue his trip to space.
According to NASA, the nearest 3i / Atlas will come to Earth is around 270 m kilometers.
“We don’t really know where it will end until it comes back to the other side of the sun and starts again to go to the external solar system,” explains Stoitsis.
Can we see the comet?
Although weak at the moment, the comet should go well as the sun approaches, which ends up “within the reach of most large amateur telescopes”, says Stoitsis.
Even then, 3i / Atlas will probably appear as a stain, he said.
“We get brilliant comets, three or four times a year, which are visible with small telescopes and binoculars. It is certainly not one of these, ”he says. “Unless you have a decent size telescope, you won’t see it.”
