The solar system is undergoing a population explosion. It’s not adding new members — they’ve been here all along. But astronomers are finding more of them.

Almost all of the newly counted are small chunks of rock and ice. Most are in the asteroid belt — a band of rocky debris between Mars and Jupiter. Astronomers are actually searching for bodies that come close to Earth — potential threats to our planet. But they also catch asteroids that are farther away. So they typically discover thousands of them every month.

They also discover asteroids that are inside Earth’s orbit. Three new ones were announced in October. One of them is the closest asteroid to the Sun yet seen. The orbit of another one crosses ours, so it could someday threaten our planet. The object is about a mile wide, so any impact would be catastrophic.

We won’t have that problem with another recent set of discoveries.

A year ago, astronomers reported more than 450 new objects in the Kuiper Belt — a region beyond the orbit of Neptune, the Sun’s most remote major planet. Some of them follow orbits that average more than 200 times Earth’s distance from the Sun.

The orbits of some of them may be influenced by the gravity of Planet Nine — a suspected giant world deep in the Kuiper Belt. So scientists are studying the orbits to help track down the elusive planet — perhaps adding one more body to the solar system’s growing population.
 

Script by Damond Benningfield