ESA, NASA Solar Observatory discovers its 5,000th comet

On March 25, 2024, a citizen scientist within the Czech Republic noticed a comet in a picture from the Photo voltaic and Heliospheric Observatory (SOHO) spacecraft, which has now been confirmed to be the 5,000th comet found utilizing SOHO knowledge. SOHO has achieved this milestone over 28 years in space, despite the fact that it was by no means designed to be a comet hunter.

The comet is a small physique product of ice and rock that takes just a few years to orbit the sun. It belongs to the “Marsden group” of comets. This group is considered associated to comet 96P/Machholz (which SOHO observes when Machholz passes close to the sun each 5.3 years) and is known as for the late scientist Brian Marsden who first acknowledged the group utilizing SOHO observations. Solely about 75 of the 5,000 comets found with SOHO belong to the Marsden group.

A joint mission of ESA (European Area Company) and NASA, SOHO launched in December 1995 to check the sun and the dynamics in its outer atmosphere, referred to as the corona. A science instrument on SOHO referred to as the Massive Angle and Spectrometric Coronagraph (LASCO), makes use of a man-made disk to dam the blinding mild of the sun so scientists can research the corona and setting instantly across the sun.

This additionally permits SOHO to do one thing many different spacecraft can not—see comets flying near the sun, referred to as “sungrazing” comets or “sungrazers.”

Many of those comets solely brighten once they’re too near the sun for different observatories to see and would in any other case go undetected, misplaced within the shiny glare of our star. Whereas scientists anticipated SOHO to search out some comets throughout its mission serendipitously, the spacecraft’s skill to identify them has made it probably the most prolific comet-finder in historical past—discovering greater than half of the comets identified right now.

In reality, quickly after SOHO launched, individuals all over the world started recognizing so many comets in its photographs that mission scientists wanted a method to hold monitor of all of them. Within the early 2000s, they launched the NASA Sungrazer Mission, which permits anybody to report comets they discover in SOHO photographs.

SOHO’s 5,000th comet was discovered by Hanjie Tan, a sungrazer Mission participant who’s initially from Guangzhou, China, and is at present pursuing a doctoral degree in astronomy in Prague, Czech Republic. Tan has been collaborating within the Sungrazer Mission since he was 13 years previous and is among the project‘s youngest comet discoverers.

“Since 2009, I’ve found over 200 comets,” Tan stated. “I acquired into the Sungrazer Mission as a result of I really like in search of comets. It is actually thrilling to be the primary to see comets get shiny close to the sun after they have been touring by space for 1000’s of years.”

A lot of the 5,000 comets found utilizing SOHO have been discovered with the assistance of a world cadre of volunteer comet hunters—many with no formal scientific coaching—collaborating within the Sungrazer Mission.

“Previous to the launch of the SOHO mission and the sungrazer Mission, there have been solely a pair dozen sungrazing comets on file—that is all we knew existed,” stated Karl Battams, a space scientist on the U.S. Naval Analysis Lab in Washington, D.C., and the principal investigator for the sungrazer Mission. “The truth that we have lastly reached this milestone—5,000 comets—is simply unbelievable to me.”

The huge variety of comets found utilizing SOHO has allowed scientists to study extra about sungrazing comets and teams of comets that orbit the sun. Comets found by the Sungrazer Mission have additionally helped scientists study extra in regards to the sun by watching the comets plunge by our star’s ambiance like small solar probes.

“The statistics of 5,000 comets, and taking a look at their orbits and trajectories by space, is an excellent distinctive dataset—it is actually precious science,” Battams stated. “It is a testomony to the numerous hours the challenge contributors have put into this. We completely would by no means have reached this milestone if it wasn’t for what the challenge volunteers have carried out.”