Now, observations made while the comet, called Atlas, was still intact, have shed light on the comet’s “family”, stretching back thousands of years.
Comet ATLAS was first detected by the Last Earth Shock Alert System or ATLAS, operated by the University of Hawaii, on December 28, 2019.
There are no records of this vision, but studying comets the way Yi and his team analyzed Comet Atlas helps them trace the comets’ origins. In fact, Atlas’ orbit around the Sun followed a similar path to the comet observed in 1844, indicating that both comets were “siblings” that came from an original comet that separated centuries earlier.
It is not uncommon for a comet to be divided into a “family”. Multiple telescopes, including Hubble and even the Galileo spacecraft, focused on Jupiter in July 1994 when Comet Shoemaker-Levy 9 was torn apart by the gravitational pull of the gas giant. The “comet train” shape is made of comet pieces that formed a line.
Astronomers predicted the demise of the comet. They watched pieces of it fall into Jupiter, forming a stunning fireball and leaving scars on the massive planet that were visible for months afterward.
Atlas Comet is different, it disintegrated when it was farther from the sun than Earth – unlike its original comet, which was closer to the sun when it crashed.
“If it separated from the sun so far, how did it survive the last passage around the sun 5,000 years ago? That is the big question,” Yi said in a statement. “It’s very unusual because we don’t expect it. This is the first time in a long time that a comet family member has been seen exploding before getting close to the sun.”
When astronomers watch a comet break into pieces, they can also work out how it held together in the first place. Comets are huge, dirty snowballs made of dust and ice that come from the edge of the solar system.
Part of Comet Atlas crashed in a matter of days, while another part survived for weeks.
“This tells us that one part of the nucleus was stronger than the other,” Yi said.
It is possible that the comet was torn apart by the material it was ejecting, or it may have shattered like fireworks.
“It’s complicated because we’re starting to see these hierarchies and the evolution of comet fragmentation,” Ye said. “The behavior of the Atlas comet is interesting but difficult to explain.”
Meanwhile, the brother of Comet Atlas, observed in 1844, will not be visible in our sky again until the 50th century.