There are comets and asteroids. The comae and tails of their cometary cousins are formed by some asteroids. Astronomers know of a few dozen examples of active asteroids, but they think there are more out there. Secrets about the history of the solar system can be found on the asteroids you spot.

steroids are easy to understand. Carbon, iron and other heavy elements can be found in the leftover bits of rocky planets. They are large balls of rock.

The comets are more active than usual. The outer edges of the solar system were formed from a mix of ices and lighter materials. When comets get too close to the sun, they become agitated, with the light elements sublimating from the surface to form a coma, and sometimes even a tail of gas.

The comparison of comets and asteroids is related.

The asteroids and comets are not the same. Astronomers found the first signs of activity in 1950. They discovered that a comet has a coma. The object was not a comet. The asteroid had a mostly rocky composition and most definitely was.

A major mystery to our understanding of the evolution of the solar system is the fact that less than 30 asteroids have been identified in the past 70 years. The small rocky bodies got enough light elements to form a coma or tail.

Here come the Centaurs 

Something important about the history of the solar system is being told by the active asteroids. One of the biggest mysteries in planetary evolution is how Earth got its water. When Earth's surface was molten or locked up within the mantle, most of our planet boiled off. Delivery systems are needed to get water on the surface. There may not have been enough comets to do the job.

We don't have many examples in the modern solar system of asteroids enriching Earth.

These asteroids are not the only ones. The small bodies of the solar system are called the Centaurs. There are asteroids between Jupiter and Neptune. The Kuiper Belt is a ring of small objects that got caught up in the gravity of the giant planets.

A sort of hybrid population is formed by the similarities between the Centaurs and comets. Unlike comets, fewer than 20 of them produce visible comaes. It's puzzling since most of the active Centaurs spend most of their time outside of Jupiter, where it's too cold to freeze light elements.

Astronomers need your help 

Astronomers have many questions about the small but distinct population of active asteroids. The Centaurs are far away from the sun. The history of light elements during the formation of the solar system is told by these active objects.

We don't have enough data to answer these questions. There are more asteroids out there, but they are hard to detect. The asteroids are small, dim and distant from the sun, but their activity is very low. It takes a lot of time and effort to find signs of a coma or a tail in asteroid images.

It's up to us to find new active asteroids, because this is a task beyond the capabilities of even the most sophisticated automated algorithm.

A new citizen-science project to hunt for active asteroids was discussed in a recent paper. The project took pictures of asteroids. The DES telescope is an ideal asteroid finder because it was not designed to look for asteroids.

To find more active asteroids, someone needs to look at the images and see if there is any activity. Simply visit and click to start. You can flip through images of asteroids and decide if they are active.

The fate of astronomy is not solely on your shoulders. Before you are passed on to the researchers, you will be compared against other people.

Analyzing active asteroids will be easier with a larger catalog of known objects. They can begin to understand what the active asteroids have to say about the history of the solar system.

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