Comet Hunters

Main-belt comets are a recently discovered population of small bodies residing in the Solar System's asteroid belt exhibiting distinctive tails that we typically associate with comets. Very little is known about main-belt comets as only about 10 have been discovered to date, but with a larger sample, we could probe the origins of the Solar System and the active processes occurring in today's asteroid belt.

View of Mauna Kea (one of the best astronomical observing sites in the world) from the Subaru Telescope Cat Walk - Image Credit: M. E. Schwamb.

Zooniverse.org has initiated the Comet Hunters project to try to greatly increase the discovery rate of these objects. Some main-belt comets were first known as inactive main-belt asteroids and then were only found to have cometary activity in later observations. Asteroids frequently appear by chance in wide-field astronomical observations, and so by scanning through these images, we may have a chance of finding more active objects. We have extracted images of known main-belt asteroids from the public archives of the Subaru Telescope, one of the largest telescopes in the world (at 8.2 meters, or 27 feet, across), located on Mauna Kea in Hawaii. None of the objects we are targeting has been previously known to show activity, but most have so far only previously been studied using small telescopes that may have missed faint activity.

Discovery image of a comet-like activity in bright main-belt asteroid Griseldis taken on the Subaru Telescope on Mauna Kea - Image Credit: Adapted from a figure by D. Tholen, S. Sheppard, C. Trujillo - original image.

This is important because we believe we can discover many more main-belt asteroids if we can detect fainter activity, and the way to detect fainter activity is to use larger telescopes like Subaru. Detecting comet-like activity is not easy. Comets can have a wide variety of appearances, and it is difficult to design automated routines to detect all the different types of cometary behavior that might exist in telescope images. In contrast, the human eye can easily spot tails of many different shapes and sizes that indicate cometary activity.

This is where you come in. By reviewing asteroid images on the Comet Hunters website to identify whether the asteroids have a tail or not, you can help find new candidate main-belt comets that the Comet Hunters science team will then follow up with ground- and space-based telescopes. Most of these chance asteroid observations have never been reviewed for cometary activity before. You just might be the first to discover that an asteroid is really a comet!

Zooniverse.org would love to see Comet Hunters incorporated into the classroom:

A wide variety of ages should be able to perform the task we are asking volunteers to do in the main classification interface in order to help identify new comets residing in our Solar System’s asteroid belt.

You might find some resources on NASA's Asteroid and Comet Watch page helpful. If you are interested in building a scale Solar System to show students where the asteroid belt is located, you can find a guide here.

The Comet Hunters Blog is also a great place to keep up with the latest science results and news from the project. Comet Hunters are currently showing images of previously discovered asteroids with well-characterized orbits.

If you develop a lesson based around Comet Hunters, please consider sharing it by uploading it to the Zooniverse Zoo Teach platform. Also, check out the Zooniverse's Education Talk discussion board to interact with the Zooniverse Education Team and other teachers interested in utilizing citizen science in the classroom.

Learn more at https://www.zooniverse.org/projects/mschwamb/comet-hunters/about/research