One of the many advantages of being in space is having a front-row seat to the most anticipated cosmic events.
NASA astronaut Don Pettit, flight engineer for the Expedition 72 crew, proved that when he witnessed Comet ATLAS from the International Space Station, orbiting 250 miles above Earth. The comet, officially known as C/2024 G3, started the week making its closest approach to the sun, and some astronomers are predicting it'll go down as the brightest comet of the year.
Pettit pointed a camera toward one of the space station's windows and caught the comet as it paid the astronauts a visit.
"It is totally amazing to see a comet from orbit," he said on X, formerly known as Twitter.
Right now Comet ATLAS appears in the constellation Sagittarius, and though it may look too close for comfort in Pettit's image, it's actually some 87 million miles from Earth. Sunlight tends to wash out such objects as they sidle up to the star, but this one can be viewed at dawn or dusk, its own brightness rivaling that of Venus, according to a NASA post.
Comets are enormous balls of ice, dust, and rock that formed in the outer solar system, left over from the early days of planet formation about 4.6 billion years ago. Their ice starts to disintegrate as they get closer to the sun, converting instantly from a solid to a gas, skipping over the liquid phase. That process creates their signature tails, millions-of-miles-long trails of debris.
Hundreds of years ago, people considered comets bad omens. Today, scientists know these icy bodies as time capsules of the ancient solar system. Some astronomers believe comets brought water and organic compounds — aka the building blocks of life — to early Earth.
As 2024 came to a close, the tally of known comets had risen to about 4,000. Astronomers say countless others are likely orbiting the sun beyond Neptune in a disk known as the Kuiper Belt, or on the outer edge of the solar system, in the so-called Oort Cloud, about 50 times farther from the sun.
The Oort Cloud is thought to be a sphere of ancient, icy objects surrounding the solar system. Comets there are sometimes dislodged by the gravity of another object, redirecting them toward the sun. This distant realm is where astronomers believe Comet ATLAS, discovered last April, originated. If it survives its close encounter with the sun, the comet may return in about 160,000 years.
Catching a glimpse of the comet anywhere north of the equator is extremely challenging, but for the Southern Hemisphere, stargazers may have a chance to see it above the western horizon shortly after sunset. This could continue from mid-January through the rest of the month.
As Comet ATLAS exits the sun's intense glare over the next day or two, it could become easier to spot. Warning: Never stare in the direction of the sun without protective eyewear.
"There is hope that Comet ATLAS will survive its close pass near the Sun and remain bright enough to be seen with the unaided eye over the next few days," NASA said.
