Some of space's weirdest exoplanets #12

WASP-17b is a planet in the constellation Scorpius. It was discovered on August 11, 2009 and it is the first exoplanet discovered to have a retrograde orbit, which is an orbit that is opposite of its star. That means that Venus, Uranus, and Pluto don't count since they are in our solar system. It is extremely massive, about 1.9 times the size of Jupiter, but its mass is extremely small, about half of Jupiter's. This puts it in a category of "puffy planets," which are planets that have extreme size but very little density. WASP-17b is the most puffy planet known. It has the density of a FOAM CUP so you can compare that.