NASA Space Technology
A bright comet from the Oort cloud named C/2023 A3 (Tsuchinshan-ATLAS) is passing by Earth and will be visible through the second half of October 2024.
This image, taken by the ESA/NASA Solar and Heliospheric Observatory (SOHO) on October 10, 2024, shows comet Tsuchinshan-ATLAS and its bright tail streaming from the upper left to the right; Mercury appears as a bright dot on the left. Image credit: ESA / NASA.
Comet Tsuchinshan-ATLAS was discovered by astronomers at the Purple Mountain Observatory in China on January 9, 2023.
Otherwise known as C/2023 A3, the comet was independently spotted by ATLAS in South Africa on February 22, 2023.
It orbits the Sun on a retrograde orbit, lying at an inclination of 139°.
It had its perihelion on September 27, 2024, at a distance of 0.391 AU; the closest approach to Earth was on October 12; it is expected to be 200 AU from the Sun in 2239.
Each day throughout October, the comet will gradually rise higher and higher in the western sky as it moves farther away from the Sun. But as it does, it will become fainter and fainter.
October 14-24 is the best time to observe, using binoculars or a small telescope.
Eagle-eyed skywatchers may be able to spot it with the naked eye for a few days, but after that, observers will likely need binoculars or a telescope to see it as it grows fainter.
“Comet Tsuchinshan-ATLAS likely came from the Oort cloud, a region of space that is between 2,000 times the distance between Earth and the Sun and a light-year,” said WVU Planetarium and Observatory Director Jason Ybarra.
“This region is so far away that the gravitational force from the Sun competes with the gravitational force from passing stars and the Milky Way Galaxy as a whole.”
NASA astronaut Matthew Dominick captured this photo of comet Tsuchinshan-ATLAS on September 28, 2024; at the time, the comet was about 70.8 million km (44 million miles) away from Earth. Image credit: NASA / Matthew Dominick.
“The larger the orbit, the longer it takes a comet to complete that orbit,” he added.
“For comets that originate from the Oort cloud, their orbits take so long that gravitational interactions with other objects in the Solar System can alter the orbit and it becomes difficult to predict their future behavior.”
“Comet Tsuchinshan-ATLAS might never return if it gets enough energy from those interactions. At minimum, you’ll have to wait another 80,000 years. Either way, it is a once-in-a-lifetime event.”
NASA astronaut Matthew Dominick captured a timelapse photo of comet Tsuchinshan-ATLAS from the International Space Station as it orbited above the South Pacific Ocean southeast of New Zealand just before sunrise on September 28.
Between October 7 and 11, the comet blazed through the view of the LASCO (Large Angle and Spectrometric Coronagraph Experiment) instrument onboard the ESA/NASA Solar and Heliospheric Observatory (SOHO).
This instrument uses a disk to block out the bright light of the Sun so it’s easier to see details and objects near the Sun.
