Help find comets skimming by the Sun

A sungrazing comet approaches the Sun from the lower left and never appeared on the other side. (The bright streak on the right is Venus) Source: Esa/Nasa Soho

A sungrazing comet approaches the Sun from the lower left and never appeared on the other side. (The bright streak on the right is Venus) Source: Esa/Nasa Soho

The Sungrazer Project crowdsources discoveries of comets - over 2,700 of them - from anyone with access to the Internet. Review images collected by Nasa’s solar observatories, find signs of comets skimming over the Sun’s surface, and report your findings… for science!

Not all comets survive their journey through the Solar System. A class of comets approach so close to the Sun that they either break up or vaporize. A German astronomer named Heinrich Kreutz studied sungrazing comets in the late 19th Century and found that they all followed the same orbit, indicating that they were the fragments of a much larger comet that broke up many centuries ago. Over time these Kreutz sungrazers spread out along their original 800-year orbit. Now as these fragments plunge to within 50,000 kilometers of the Sun’s surface the incredible heat vaporizes them, never to be seen again.

Even though astronomers have known about sungrazing comets for centuries, the Sun is so bright that astronomers could only see the rare, large comet. Only 9 sungrazing comets had been found before the age of space-based observatories arrived. Thanks to the Esa/Nasa Solar and Heliospheric Observatory (Soho), professional and amateur comet-spotters have discovered over 2,700 sungrazing comets. 

Soho and the twin Stereo (Solar Terrestrial Relations Observatory) spacecraft record gigabytes of data about the Sun and its environment every day. Coronagraphs, the main tool for comet-hunters, let solar scientists study the Sun’s faint outer layers and solar storms - they weren’t intended for comets at all! But blocking the Sun’s surface lets the much fainter light reflected from comets appear in the images streaming to Earth from the observatories. This video taken by Nasa’s Stereo B spacecraft shows the comet C/2011 L4 (Panstarrs) passing within 50 million kilometers of the Sun (just off the screen to the left). You can see Mercury and Earth in the background as well as solar storms erupting from the Sun’s surface. 

Scientists at the US Navy Research Laboratory have run the Sungrazer Project with Nasa support since 2000. The Soho and Stereo mission teams post images from the spacecraft in near real-time. The Sungrazer site provides tutorials and example images that explain how to find comets in those images. Amateur space explorers check for signs of sungrazing comets and then submit reports of the comet’s position through the project’s online forms. Karl Battam, the project’s coordinator, checks the data before submitting them to the Minor Planet Center’s database.

The database of sungrazing comets lets solar and planetary scientists conduct a wide range of research that wouldn’t be possible without the public’s health. In a press release celebrating Soho’s 1500th comet discovery, Battams said "This is allowing us to see how comets die. It is a unique data set and could not have been achieved in any other way.”