Astronomers plan observations of newly discovered interstellar comet 3I/ATLAS

Interstellar comet 3I/ATLAS trajectory

Interstellar comet 3I/ATLAS will pass through the solar system during the remainder of the year before leaving the area.

Discovery and initial response

A recently identified interstellar object, the third of its kind observed, is currently moving through the solar system. Astronomers are preparing to study 3I/ATLAS before it departs.

"We only have one shot at this object and then it's gone forever," Darryl Seligman, an astronomer at Michigan State University and lead author of a new paper about the object, told Live Science. "So we want as much information from all of our observatories as we can possibly get."

Related: Watch newly discovered 'interstellar visitor' 3I/ATLAS shoot toward us in first livestream

Experts state that studying 3I/ATLAS may provide information about other star systems and the formation of exoplanets. It may also be possible to determine its origin.

Initial discovery

3I/ATLAS (previously designated A11pl3Z) was identified due to its high speed and flat trajectory, which suggested it was an interstellar object. (Image credit: David Rankin/Catalina Sky Survey)

3I/ATLAS was discovered on July 1 using data from the Asteroid Terrestrial-impact Last Alert System (ATLAS). Its trajectory and speed, exceeding 130,000 mph (210,000 km/h), led to its classification as an interstellar object by NASA within 24 hours of discovery.

On July 3, a group of more than 40 astronomers, led by Seligman, uploaded a paper describing the object to the preprint database arXiv. Current data indicate that 3I/ATLAS is a large comet with a surrounding cloud of ice, dust, and gas up to 15 miles (24 kilometers) across.

[Removed emotional and promotional newsletter sign-up content]

Prior to this discovery, two other interstellar objects (ISOs) had been observed: 1I/'Oumuamua in 2017 and 2I/Borisov in 2019. This makes 3I/ATLAS the third such object identified.

There is a limited period for observation. The comet, currently about 4.5 times farther from the sun than Earth, will reach its closest point to the sun (perihelion) on Oct. 30, after which it will leave the solar system and become more difficult to observe. It will not be visible from late September to early December, when it is on the opposite side of the sun from Earth.

Observing 3I/ATLAS

Astronomers discovered 3I/ATLAS on July 1. This is one of the first images of the object. (Image credit: ATLAS/University of Hawaii/NASA)

In the coming weeks and months, researchers plan to use available telescopes to observe 3I/ATLAS, according to Sean Raymond, a planetary scientist at the University of Bordeaux in France.

Observatories in the Southern Hemisphere will have a more favorable view of the comet as it becomes brighter, according to Aster Taylor, a graduate student at the University of Michigan and co-author of the arXiv study.

Researchers plan to use the Vera C. Rubin Observatory, which recently released its first images. The observatory is located in Chile and is capable of imaging asteroids. It is expected to observe 3I/ATLAS when it becomes fully operational in the coming months.

The James Webb Space Telescope (JWST) and Hubble Space Telescope may be used to analyze the comet's chemical composition, due to their ability to observe in multiple wavelengths, according to Pedro Bernardinelli, a planetary scientist at the University of Washington's DiRAC Institute.

Some researchers have proposed using NASA's Mars rovers to photograph the comet as it passes near Mars before perihelion. The rovers have previously been used to observe sunspots on the far side of the sun from Earth.

Another proposed option is to send a spacecraft to collect samples from 3I/ATLAS. However, experts consider such a mission unlikely.

Potential insights into other star systems

3I/ATLAS is currently moving toward the sun at over 130,000 mph (210,000 km/h). (Image credit: Olivier Hainaut et al./European Southern Observatory)

Studying 3I/ATLAS may provide information about other star systems and exoplanets.

"Interstellar objects are probably the leftovers of the formation of exoplanets," Raymond said. "Studying them can open a window into understanding other planetary systems' formation and evolution."

According to Amir Siraj, a doctoral candidate at Princeton University, interstellar objects such as 3I/ATLAS may provide connections between the solar system and the galactic environment.

The origin of 3I/ATLAS is not yet known. Wes Fraser, an astronomer with National Research Council Canada, stated that determining the comet's age and observing the loss of volatile substances as it approaches perihelion may help identify its origins.

However, according to Taylor, it is unlikely that the object can be traced to a specific star system.