Some Comet ‘Sungrazers’ Could Be Asteroid Hybrids, Scientists Find

Scientists found that some sungrazing comets could actually be asteroids. Sungrazers are comets that come extraordinarily close to the sun during their long and looping orbits around the solar system.

According to a report from Forbes, a comet is considered a sungrazer if it passes closer than about 850,000 miles from the surface of the sun - a distance even smaller than the diameter of the sun.

The Solar and Heliospheric Observatory (SOHO) spacecraft is designed to observe the sun and its thin atmosphere, as well as sungrazers that happen to pass by. Over the last 20 years, SOHO has discovered more than 3,000 of these sungrazing comets.

But recently, SOHO has discovered an object called 322P/SOHO 1, which contains some properties of asteroids or space rocks, instead of a mix of ice and dust that comets typically have.

"We found it kind of looks like an asteroid and it kinds of looks like a comet," Karl Battams, an astrophysicist at the Naval Research Laboratory in Washington, D.C., said in an interview with Seeker. "There's a weird hybrid thing going on. The results were indeterminate, so we're not sure if this is something that was once a comet... or maybe an asteroid that got stuck. There's no definitive conclusion there."

About 86 percent of SOHO-observed sungrazers are comets, and they belong to a specific family called Kreutz comets, Seeker reports. The remaining 14 percent, however, are difficult to categorize, as they don't fit in any of the other group's properties. According to Battams, these other sungrazers could be the cores of comets or asteroids that got close to the sun.

Battam points out the importance of knowing about these sungrazers, as he recalled a group of sungrazers that passed extremely close to the Moon's orbit in 2008. These objects need to be tracked in case some pose a threat to Earth.

But according to Jillian Scudder, astrophysicist and contributor at Forbes, sungrazing asteroids are less common than sungrazing comets. While comets typically have more elongated looping orbits, asteroids follow a more circular orbit that keeps them away from the sun.

The findings were discussed in a paper published on arxiv, which has been recently accepted in the journal Philosophical Transactions A.