Episode for July 22nd, 2023 Download

One of the most exciting recent discoveries in astronomy has been the existence of planets around other stars. Called exoplanets, they vary wildly in their characteristics, appearance and behavior.

Most of the over 5000 exoplanets discovered so far are in orbit around other stars, some whiz around their home sun in a matter of only days while others have orbits that last decades or hundred of years.

But there is another interesting class of exoplanets that do not have a home sun. These rogue worlds travel the distance between the stars, they live in the cold, dark interstellar regions of the galaxy.

Free floating planets like this are very difficult to spot. Since we have found most exoplanets by looking at them indirectly, like watching the star’s brightness dip as it passes in front or makes the star wobble as it pulls it in its orbit, there is not much to go on to find the roaming exoplanets around no star at all - we do not have the technology to image them directly.

Still, amazingly, astronomers have found some, over 70 exoplanets that do not have a host star have been found roaming the galaxy. Using over 20 years worth of data from dozens of telescopes, astronomers have uncovered some of the dimmest objects in our Milky Way, and some of them are planets.

Most interesting of all, if any of these free floating planets happen to have a moon around it, and the exoplanet itself is large enough, like Jupiter say, astronomers surmise that the heat generated by the gravity of these systems might actually be enough to harbor life on the revolving moon. If we could find life on a world like that, it would be a strong argument that life in the universe is everywhere.