Say aloha to solar system’s third known interstellar visitor 3I/ATLAS, detected by University of Hawaiʻi telescope

A University of Hawaiʻi telescope detected the third known object to visit our solar system from outside its boundaries.

The discovery was made by the NASA-funded Asteroid Terrestrial-impact Last Alert System, or ATLAS, telescope in Rio Hurtado, Chile. ATLAS is a global network of four telescopes managed by University of Hawaiʻi Institute for Astronomy that scan the skies for asteroids that could pose a threat to Earth.

Researchers say our newest interstellar visitor — which poses no danger to Earth — is moving right through the Milky Way, making it difficult to distinguish amidst all the stars.

But this is one of the four-telescope network’s strengths.

“Spotting a possible interstellar object is incredibly rare, and it’s exciting that our [University of Hawaiʻi]-operated system caught it,” said Institute for Astronomy astronomer and professor John Tonry in a release about the visitor’s arrival. “The chances of one actually hitting the Earth are infinitesimal, less than 1 in 10 million each year, but ATLAS is continually searching the sky for any object that might pose a problem.”

The newly identified object, designated A11pl3Z, was added July 1 to the International Astronomical Union’s Near-Earth Object confirmation list. A Minor Planet Electronic Circular was just released naming it 3I/ATLAS.

Its trajectory and speed moving toward the sun confirm it originated from outside our solar system — and it will leave the solar system again after passing the sun.

Early estimates suggest 3I/ATLAS could be as large as 12 miles in diameter. Researchers say it will make its closest approach to the sun — about twice the distance from Earth — in October, traveling at more than 150,000 miles per hour.

“These interstellar visitors provide an extremely interesting glimpse of things from solar systems other than our own,” Tonry said. “Quite a few come through our inner solar system each year, although 3I/ATLAS is by far the biggest to date.”

While 3I/ATLAS appears on the Near-Earth Object list and has no risk of hitting Earth, or even a close pass, it is sobering that if it struck the blue planet we call home — and again, it will not — it would create an explosion more than 100 times greater than the asteroid that killed the dinosaurs.

Researchers suspect that 3I/ATLAS is a comet and it should show increasing activity as it gets closer to the sun, but it will never get warm enough to be seen by the naked eye.

The detection of 3I/ATLAS marks our solar system’s third time saying aloha to an interstellar visitor, following the discoveries of ʻOumuamua in 2017 and comet 2I/Borisov in 2019.

ʻOumuamua was first detected by University of Hawaiʻi’s Pan-STARRS1 telescope atop Haleakalā on Mau and became the first object to receive an official interstellar designation.

It caught global attention with its strange, elongated shape and unexpected acceleration as it exited the solar system.

Although it showed no visible tail, its motion suggested comet-like behavior.

Most scientists now agree that it was a natural object, likely a comet from another star system, although its exact nature is still debated.