Overview

Most of the exoplanets discovered so far are in a relatively small region of our galaxy, the Milky Way. We know from NASA’s Kepler Space Telescope that there are more planets than stars in the galaxy.

By measuring exoplanets’ sizes (diameters) and masses (weights), we can see compositions ranging from very rocky (like Earth and Venus) to very gas-rich (like Jupiter and Saturn). Exoplanets are made up of elements similar to those of the planets in our solar system, but their mixes of those elements may differ. Some planets may be dominated by water or ice, while others are dominated by iron or carbon. We’ve identified lava worlds covered in molten seas, puffy planets the density of Styrofoam and dense cores of planets still orbiting their stars.

Credits: NASA/W. Stenzel

The first exoplanets were discovered in the 1990s and since then we’ve identified thousands using a variety of detection methods. It’s pretty rare for astronomers to see an exoplanet through their telescopes the way you might see Saturn through a telescope from Earth. That’s called direct imaging, and only a handful of exoplanets have been found this way (and these tend to be young gas giant planets orbiting very far from their stars).

Related

• Citizen Science 

Now we live in a universe of exoplanets. The count of confirmed planets is in the thousands and rising. That’s from only a small sampling of the galaxy as a whole. The count could rise to the tens of thousands within a decade, as we increase the number, and observing power, of robotic telescopes lofted into space.

Welcome to Barboza Space Center’s First School on Mars

We have created a simulated planet for our hands on space science program. Here is our photo essay.