Interstellar object 3I/ATLAS is on the opposite side of the sun from Earth – but several spacecraft are in the perfect position to get a closer look.
As 3I/ATLAS warps and grows the closer it gets to our solar system’s star, public fascination with the unusual cosmic outsider only seems to become stronger. The object is one of only three space objects originating from a star other than our sun to be spotted in Earth’s cosmic neighborhood.
Over the past several days, two spacecraft orbiting Mars imaged the massive object as it passed by the Red Planet. Here’s an update on 3I/ATLAS, including new photos, details on additional images, and more.
What is comet 3I/ATLAS?
A comet known as 3I/ATLAS made news in July when it was confirmed to have originated outside Earth’s solar system. When it was discovered, the interstellar comet was moving at about 137,000 miles per hour – and it’s expected to continue picking up speed as it continues its journey toward the sun.
The Minor Planet Center, an official authority for observing and reporting new comets and other small bodies in the solar system, recorded the comet’s observation. The object, which was eventually confirmed to be almost certainly a comet and named 3I/ATLAS, was later found to have interstellar origins.
More: What is 3I/ATLAS? Here’s what NASA says about this rare interstellar celestial visitor
Mars orbiters 3I/ATLAS images
The two Mars orbiters able to observe 3I/ATLAS from Oct. 1-7 were Mars Express and ExoMars Trace Gas Orbiter. The comet came closest to the Red Planet on Oct. 3, passing at a distance of roughly 18.6 million miles from the two spacecrafts as they orbited Mars, according to the European Space Agency.
Both of the spacecraft have cameras designed to photograph the bright surface of Mars, just a few hundred to a few thousand miles below. This meant that the orbiters struggled to capture accurate measurements from millions of miles away.
In images captured by the ExoMars, 3I/ATLAS appears as a fuzzy white dot moving downward near the center of the pictures. The dot marks the comet’s center, which comprises its icy-rocky nucleus and the surrounding coma.
Scientists continue to analyze the images captured by the Mars Express to see if they can spot the faint comet, according to the agency.
“Though our Mars orbiters continue to make impressive contributions to Mars science, it’s always extra exciting to see them responding to unexpected situations like this one,” Colin Wilson, project manager for both missions at the ESA, said in a statement. “I look forward to seeing what the data reveals following further analysis.”
ESA’s ExoMars Trace Gas Orbiter caught this glimpse of 3I/ATLAS from about 18.6 million miles away on Oct. 3 as the interstellar comet passed by the Red Planet on a journey toward the sun.
When will there be more photos of 3I/ATLAS?
Further photos of the comet will be taken by the ESA’s Jupiter Icy Moons Explorer – also known as “Juice” – between Nov. 2-25. The object is expected to be in a “very active state” at this point, following its closest approach to the sun.
However, as the spacecraft is so far from Earth on the opposite side of the sun, scientists don’t expect to receive its observations until February, according to the ESA.
The object will reappear in December on the other side of the sun, making it visible from Earth once again.
Why is 3I/ATLAS such a big deal? Hubble telescope to view 3I/ATLAS
Unlike comets bound to the sun’s gravity, 3I/ATLAS is traveling on a hyperbolic orbit that will eventually carry it out of the solar system and back into interstellar space. That’s why, even though the comet poses no threat to Earth, the world’s astronomers and space agencies are racing to study planetary material that formed from another star.
A fleet of NASA space telescopes has already been returning plenty of images and data back to Earth, gathered from glimpsing the comet.
NASA’s iconic Hubble Space Telescope previously observed the comet in July, collecting data that allowed astronomers to estimate the size of the comet’s solid, icy nucleus as ranging from 1,000 feet to 3.5 miles wide.
The James Webb Space Telescope then observed the interstellar object on Aug. 6 in near-infrared light, followed by the newer SPHEREx telescope from Aug. 7 to Aug. 15 to better understand its physical properties and chemical makeup.
More recently, a ground-based telescope in Chile glimpsed the comet’s glowing tail, which observations reveal has steadily grown as it cruises toward the sun. The Gemini South telescope in Chile, operated by the National Space Foundation’s NoirLab, collected observations showing that 3I/ATLAS displays a prominent tail and a broad coma, or a cloud of gas and dust that forms around the comet’s icy nucleus as it gets closer to the sun.
How did 3I/ATLAS get its name?
3I/ATLAS is named for its status as one of three interstellar objects ever discovered in our cosmic neighborhood, as well as for the NASA-funded telescope that spotted it: ATLAS, short for Asteroid Terrestrial-impact Last Alert System.
What was the first interstellar object detected in the solar system?
Comet Oumuamua, Hawaiian for “scout” or “messenger,” became the first interstellar object ever detected in the solar system in 2017, followed by the comet Borisov in 2019.
How close will 3I/ATLAS get to Earth?
The closest 3I/ATLAS will approach Earth is about 170 million miles, according to NASA.
The object will instead pass a little closer to the sun, coming within 130 million miles on Oct. 30. For reference, the sun is about 93 million miles away from Earth.
What’s the difference between a comet and an asteroid?
Asteroids are made up of rocky material left over from our solar system’s formation. Most reside in the main asteroid belt between the orbits of Mars and Jupiter.
Telescope observations, though, helped astronomers determine that 3I/ATLAS displays all the telltale signs of a comet. That’s because the object is still active, meaning it’s composed of not just rock but also has an icy nucleus and a bright cloud of gas and dust, known as a coma, surrounding it.
That material begins to heat up and spew out the closer a comet gets to the sun.
Eric Lagatta, USA TODAY, contributed to this report.
Iris Seaton is the trending news reporter for the Asheville Citizen Times, part of the USA TODAY Network. Reach her at iseaton@citizentimes.com.
This article originally appeared on Asheville Citizen Times: What is comet 3I/ATLAS? See new Mars orbiters 3I/ATLAS images, more
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