A chunk of ice and dust plunged towards the sun yesterday morning, and one satellite was watching the show live. ESA and NASA’s Solar and Heliospheric Observatory (SOHO) saw a bright comet travel behind the sun, but it didn’t emerge from the other side.
Traveling at 1.3 million miles per hour, this comet couldn’t survive its close encounter. Most sungrazing comets rarely do.
“This comet didn’t fall into the sun, but rather whipped around it – or at least, it would have if it had survived its journey,” NASA said in a statement. “Like most sungrazing comets, this comet was torn apart and vaporized by the intense forces near the sun.”
What makes a sungrazing comet?
Sungrazing comets often have incredibly elliptical orbits. At their farthest point, these class of comets orbit beyond Pluto. But to be considered a sungrazer, the comets have to come within 850,000 miles of the sun during perihelion (closest point to the sun).
Many come well within 850,000 miles. And that’s why most never emerge from the other side. Solar radiation boils off much of the ice. Combine that with the sun’s intense gravity and it’s no wonder NASA rarely sees a sungrazer comet make to the other side.
But it does happen. On December 16, 2011, Comet Lovejoy (C/2011 W3) reached perihelion at just 87,000 miles above the Sun’s surface. While Comet Lovejoy whipped around the sun still intact, the sun took its toll on it.
Did You Know: There are five Comet Lovejoy’s. Each named after the person who discovered them, amateur astronomer Terry Lovejoy. C/2014 Q2 (Lovejoy) is the most recent one discovered and the one you probably think of when you hear Comet Lovejoy. That comet is known to release vast quantities of alcohol (the equivalent of at least 500 bottles of wine every second during peak activity).
C/2011 W3 (and the comet seen yesterday) are part of a family of comets called Kreutz sungrazers. This family of comets are believed to be the fragments of one large comet that broke apart centuries. They’re named after the German astronomer Heinrich Kreutz, who demonstrated the comets are related.
Every Kreutz sungrazer travels along a similar orbit dubbed the Kreutz Path. Nearly 85% of all sungrazer comets spotted by the SOHO satellite follow this path. At their closest point, Kreutz stargazers fall within the 850,000-mile threshold. But they begin their sunward journey at an aphelion (farthest distance from the sun) of about 170 AU. That’s more than three times as far away as Pluto.
How sungrazers help scientists learn more about the sun
Sungrazers don’t just make a good visual show. They can also help scientists learn more about the sun. When Comet Lovejoy was being hammered by the sun, tails of ionized gas showed the sun’s invisible magnetic field.
SOHO’s mission is to thoroughly study the sun from its deep core to the solar wind. And every now and then, show us cool moments like the one above.