Scientists Track Rare Interstellar Comet 3I/Atlas as It Approaches Sun

An intriguing interstellar comet, designated as 3I/Atlas, is on a trajectory toward the sun, moving at approximately 61 kilometers (38 miles) per second. Discovered in July 2023, this object is only the third interstellar visitor recorded, following the appearances of ‘Oumuamua in 2017 and 2I/Borisov in 2019. The Hubble Space Telescope recently captured images of 3I/Atlas, fueling excitement among scientists eager to study its characteristics and origins.

According to Dr. Rebecca Allen, co-director of Swinburne University’s Space Technology and Industry Institute, “We’ve never had an object like this to study before.” Dr. Laura Driessen, a radio astronomer at the University of Sydney, adds that while the exact origin of 3I/Atlas remains unknown, it is confirmed to have come from outside our solar system. The name “3I/Atlas” reflects its interstellar classification, being the third such object identified, and is derived from the Asteroid Terrestrial-impact Last Alert System (Atlas) that first detected it.

Some speculation has arisen regarding the possibility of alien life associated with 3I/Atlas, echoing the debates surrounding ‘Oumuamua. Nevertheless, scientists emphasize that it is likely a comet. “There’s no evidence to point towards [3I/Atlas] being anything other than a really fun space rock that came from outside the solar system,” Driessen states. “Which, to be honest, is cool enough.”

What Scientists Hope to Learn

The Hubble images reveal that 3I/Atlas resembles a “fuzzy snowball,” according to Allen, due to its coma—a cloud of gas and dust generated by the heating of its surface as it nears the sun. The comet is also exhibiting early signs of a tail. As it approaches, scientists expect to gather more chemical data, which will allow them to analyze its composition through a method known as spectroscopy. This technique will help determine whether the comet’s chemical makeup indicates conditions similar to those of our solar system or if it presents something entirely different.

Current estimates place the diameter of 3I/Atlas at less than 5.6 kilometers, with the possibility of it being as small as 320 meters. The comet is traveling at speeds exceeding 200,000 kilometers per hour and will traverse the inner solar system, passing between the orbits of Mars and Earth before making a close approach to the sun.

A Unique Trajectory and Viewing Opportunities

3I/Atlas is on a hyperbolic orbit, meaning it is not gravitationally bound to the sun. Once it flies past, it will exit the solar system at a significant speed. According to Con Stoitsis, the comet and meteor director at the Astronomical Society of Victoria, it is anticipated to come within approximately 210 million kilometers of the sun between October and December 2023. The closest it will pass to Earth is estimated to be about 270 million kilometers.

As for visibility, while 3I/Atlas is currently faint, it is expected to brighten as it nears the sun. Stoitsis notes that it will likely become visible through large amateur telescopes, although it may appear as a mere smudge in the sky. “We get bright-ish comets, three or four times a year, which are visible with small telescopes and binoculars. This is definitely not one of those,” he explains. “Unless you’ve got a decent-sized telescope, you won’t see it.”

The approach of 3I/Atlas presents a significant opportunity for astronomers to gather insights into the nature of interstellar objects, enhancing our understanding of the universe beyond our solar system.