By Angus Dalton
Astronomers are racing to determine the nature of a big, bright, superfast object from beyond our solar system hurtling towards the sun.
The European Space Agency said it could be the third-ever confirmed object we’ve detected in our cosmic neighbourhood that originated from outside our solar system.
An image of New Interstellar Object #A11pl3Z captured by astronomer David Rankin in Arizona.Credit: David Rankin, Saguaro Observatory
The agency is monitoring the eccentric path of the ultra-rare interstellar object, provisionally called A11pl3Z, through a network of telescopes across the globe.
The object is sailing past Jupiter’s orbit at more than 60 kilometres a second and will fly deep into the solar system, skimming past Mars.
“It’s travelling whoppingly fast at an estimated 245,000km/h,” said Swinburne University of Technology astrophysicist Sara Webb. “It is absolutely yeeting it through the solar system.”
That sensational speed is the giveaway that this is probably a visitor from beyond our solar system.
The estimated trajectory of interstellar visitor A11pl3Z.Credit: Tony Dunn (@tony873004)
Asteroid belts and comets orbiting around the sun travel at speeds below the “escape velocity” of the sun’s gravitational pull. Any faster and they’d rocket off into the dark of deep space.
“This object, though, it looks like it is travelling at a speed that would not allow it to remain within our solar system’s orbit,” Webb said.
“It means this is an object that was potentially kicked out of a different system in our Milky Way, and it’s been travelling interstellar space until it’s been captured just very briefly by our own solar system.”
The first-ever interstellar object in our solar system was detected by an observatory in Hawaii in 2017 and named Oumuamua, which means “messenger from afar”. The second was a rogue comet called 2I/Borisov in 2019.
An artist’s impression of interstellar asteroid Oumuamua, discovered in 2017 and described as “unlike anything normally found in the solar system”.Credit: ESO/M. Kornmesser
The object may be another icy rogue comet or a rocky asteroid. Early analysis shows it may be 20 kilometres across, dwarfing Oumuamua and 2I/Borisov, both estimated at about a kilometre long. That’s also bigger than the asteroid that killed the dinosaurs, but there’s no chance A11pl3Z will strike Earth.
“In our grand scheme of understanding, we have not had very many of these to actually investigate and interrogate. So that is very exciting,” Webb said.
Interstellar interlopers are so rare partly due to the vastness of space. Rogue comets could travel for billions of years through the depths of the universe and never feel the warmth of a star.
But the opening of a powerful new observatory on the foothills of the Andes in Chile has just turbocharged our ability to monitor such visitors when they do pass by, said astronomer Michael Brown, an associate professor from Monash University.
Extraordinary images of space released by the Vera C. Rubin Observatory last week.Credit: NSF-DOE Vera C. Rubin Observatory
The Vera C. Rubin Observatory is the biggest digital camera ever built, at 1.7 metres and 3200-megapixels.
Brown said the observatory would trigger the discovery of a “tidal wave” of these objects, which would unlock secrets about neighbouring solar systems as they fling visitors our way.
“Once we start seeing more of them, we might get a sense of where they’re coming from,” Brown said.
“We’d expect a lot of these interstellar asteroids and comets to be ejected from young solar systems … it’ll give us a sense of how other solar systems are forming and how messy they are when they’re being born.”
The Examine newsletter explains and analyses science with a rigorous focus on the evidence. Sign up to get it each week.