Super-Puff Planets

How's that for the name of a type of planet? Super-puff planets! As the name suggests, super-puff planets are planets that are, well, super puffy! In our own Solar System we have the large gas giants of Jupiter, Saturn, Uranus, and Neptune. Of these four gas giants, Saturn has the lowest density at about 70% that of water. This means that Saturn could float in water if there was a bath big enough to fit Saturn. Super-puff planets have an even lower density.

 

 

This illustration depicts Kepler-51 and its three giant planets. Image credit: NASA / ESA / L. Hustak, J. Olmsted, D. Player & F. Summers, STScI.

Super-puff planets have a mass less than that of our Solar System's gas giants. Their masses are typically no more than a few times that of Earth, but they have radius (physical size) larger than Uranus and Neptune. A smaller mass with a larger size gives a much lower density at less than 10% that of water. That is seven times less dense than Saturn!

There are not many of these super-puff planets known to exist, with numbers less than 20, but as we look for and discover more planets, we are bound to find more super-puff planets. For more information on these very cool exoplanets, I encourage you to read the following article.

Kepler-51 is Home to Three Super-Puff Exoplanets

Until I read this article, I had never heard the term super-puff applied to new planets. That is the exciting thing about science. Keep your eyes and ears open to science and you learn something new every day!