By science reporter Jacinta Bowler
3I/ATLAS was discovered earlier this week, and recently confirmed as an interstellar object. Photo: CC BY-SA 4.0 / K Ly at Deep Random Survey
- Astronomers have discovered a new object that originated from outside of our Solar System. It's only the third to be found.
- The interstellar object, designated 3I/ATLAS, will make its closest approach to the Sun in October.
- As it has been discovered early, scientists will have months to collect and analyse data on the object before it exits the Solar System next year.
For only the third time in history, astronomers have discovered a new interstellar object that originated from outside our Solar System.
The object, known as 3I/ATLAS, is likely a comet and is much faster than any other interstellar object found before.
The object appears to be hurtling towards our Sun at about 60 kilometres a second.
"This thing is coming in at such an incredible speed that absolutely nothing in the Solar System could have caused this," Jonti Horner, an astronomer at the University of Southern Queensland, said.
"Of the three interstellar objects we have seen, this is by far the fastest."
There are only two other interstellar objects that have previously been tracked entering our Solar System - 'Oumuamua and Comet 2I/Borisov.
"It's so exciting," Professor Horner added.
Rumblings of the potential interstellar object started in astronomy groups when the object was first detected early this week.
"It has been picked up so early - relatively speaking - that we've got at least eight months [during which] we'll be able to observe it," he said.
How was 3I/ATLAS found?
The object was first detected by the ATLAS telescope in Chile on 1 July.
Follow-up observations confirmed the orbit was extremely unusual - almost unaffected by the Sun's gravity, Professor Horner said.
"Plotting the orbit of this thing [shows] it barely bends as it goes past the Sun."
The trajectory of interstellar comet 3I/ATLAS as it passes through the Solar System. Photo: CC 1.0 Universal Public Domain Dedication / Tony873004
But it wasn't until yesterday that scientists at the Minor Planet Centre in the US confirmed the object was an interstellar object.
They also suggested the object was likely a comet, due to images that showed it had a short tail.
More observations will need to be done to confirm this, and get more detail about the object.
However, because 3I/ATLAS has been found so early, astronomers will have plenty of time to track it as it moves through the Solar System.
When will 3I/ATLAS be closest to the Sun?
Currently, estimates suggest it will be closest to the Sun at the end of October, before returning out past Jupiter and into the outer Solar System by March next year.
Unfortunately, Earth will be on the other side of the Solar System when 3I/ATLAS is closest to the Sun and at its brightest, making it harder for us to see.
"If we were on Mars, we'd have a fairly good view of it," Professor Horner said.
"It's not going to be hugely close to Mars, but it's going to be a lot closer to Mars than it will to the Earth."
How big is 3I/ATLAS?
Because 3I/ATLAS might currently be going through an outburst - a sudden brightening caused by dust and gas being released by the object - it's difficult to track its size.
'Oumuamua was quite a small object, and estimates on the size of 2I/Borisov ranged from about 1 kilometre to more than 16km in diameter.
"I would say this is probably more along the lines of a few hundred metres to a kilometre across, maybe a bit bigger than that," Professor Horner said.
"Which is big, but not exceptional."
Will we see more interstellar objects?
With the first images from the Vera C Rubin Observatory released just last week, it's likely that this is just a taste of what is to come.
Interstellar objects have been extremely rare so far, but with better telescopes like the Rubin Observatory, we're likely to catch many more of these objects when they arrive.
"We've had three [interstellar objects] in less than a decade with our current technology," Professor Horner said.
"The Rubin Observatory is probably an order of magnitude better at finding things … so that would suggest we'll find a few of these per year."
Within its first 10 hours of operation the observatory detected more than 2000 previously unknown asteroids in the Solar System.
"It's kind of a sneak peek into the future."
- ABC
