NRL’s Sungrazer Project Discovers 5000th Comet

WASHINGTON  –   On March 25, the U.S. Naval Research Laboratory’s (NRL) Sungrazer Project reached a remarkable milestone – the discovery of its 5,000^th comet in data from the joint European Space Agency – National Aeronautics and Space Administration (ESA-NASA) Solar and Heliospheric Observatory (SOHO).
 
The Sungrazer Project is a NASA-funded citizen science program operating from NRL for over 20 years, and enables volunteers from anywhere in the world to submit reports of suspected new near-Sun and “sungrazing” comets in NASA and ESA heliophysics imaging data.
 
Almost all of the project’s 5,000 discoveries have been made in images returned by NRL’s Large Angle Spectrometric Coronagraph (LASCO) telescope which has operated continuously aboard the SOHO satellite since 1995.
 
LASCO is a coronagraph telescope, designed to return visible-light images of the solar corona and near-Sun region, to aid in the study of solar eruptions and outflows. However, the high-sensitivity of the instrument has also led to an unanticipated wealth of observations of previously unknown comets as they pass extremely close to the Sun and begin vaporizing. Due to their proximity to the Sun, these comets are invisible from Earth, and can only be seen by specialized instrumentation like LASCO.

“When LASCO was launched, no one had any idea that it would turn out to be the most prolific discoverer in history,” said NRL researcher Karl Battams, Ph.D., the principal investigator of LASCO and the Sungrazer Project. “The amount of data and science returned has just been beyond our wildest dreams.”
 
The 5,000^th discovery was made by amateur astronomer Hanjie Tan from Guangzhou, China, who is currently an astronomy Ph.D. student in Prague, Czech Republic. Tan has been participating in the Sungrazer Project since he was 13 years old, making him one of the project’s youngest comet discoverers.  He spotted the images from LASCO’s C2 camera. Unlike most of SOHO’s comets, it very probably survived its passage by the Sun. It will have passed approximately 8.2 million kilometers (5.1 million miles) from the Sun – this is slightly farther from the Sun than the current orbit of NASA’s Parker Solar Probe, which carries NRL’s WISPR imaging instrument.
 
SOHO-5000 is a small, short-period comet belonging to the so-called ‘Marsden group’ of comets, named for the late Dr. Brian Marsden who first recognized the group. The Marsden group was not known to exist until SOHO (LASCO) discovered it. The group is believed to be an ancient descendants of the Near-Sun comet 96P/Machholz, which NRL’s LASCO observes every 5.3 years. Only approximately 75 of SOHO’s 5,000 comets belong to this comet group.
 
VIDEO: On March 25, the U.S. Naval Research Laboratory’s (NRL) Sungrazer Project reached a remarkable milestone – the discovery of its 5,000th comet in data from the joint European Space Agency – National Aeronautics and Space Administration (ESA-NASA) Solar and Heliospheric Observatory (SOHO). The 5,000th discovery was made by amateur astronomer Hanjie Tan from Guangzhou, China, who is currently an astronomy Ph.D. student in Prague, Czech Republic. SOHO-5000 is a small, short-period comet belonging to the so-called ‘Marsden group’ of comets, named for the late Dr. Brian Marsden who first recognized the group. The Marsden group was not known to exist until SOHO (LASCO) discovered it. (Credit: NRL/ESA/NASA)
 
The crowd-sourced discovery of comets in SOHO/LASCO observations has led to a wealth of new science regarding the compositional properties of comets, their photometric behavior, and their physical properties, as well as orbital evolution and fragmentation. Studies of these comets also aids our understanding of the Sun, allowing scientists to study the way the comets and their tails react to, and interact with the extreme near-Sun region, including the Sun’s magnetic fields and outflows. LASCO is one of the most impactful heliophysics instruments in history, currently providing critical realtime imagery of solar eruptions that can lead to potentially disruptive space weather events.
 
The SOHO project is reaching the end of its planned lifetime. It was originally a two-year mission, and has now stretched to nearly 30 years. It is currently scheduled to cease operations at the end of 2025. “It will be truly sad when the SOHO mission finally ends,” said Battams, “but the discoveries that it has made over nearly the past 30 years have completely revolutionized heliophysics and comet science, so we have so very much to thank SOHO for.” 
 
 
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