When is a planet too big to be called a planet?
There have been quite a few discussions on what makes a planet (and what doesn't) in the past, the most famous of which resulted in the infamous demotion of Pluto from planet status. But now, there's some rumblings on the upper end of things. This week, Kevin Schlaufman published an article in The Astrophysical Journal proposing the maximum size something can be and still be considered a planet: between four and ten times the mass of Jupiter. Jupiter is, in turn , approximately 317 times as massive as Earth. Schlaufman specifically narrows in on the difference between gas giants, like Jupiter or Saturn, and brown dwarfs. Brown dwarfs are, essentially, failed stars and occupy a strange in-between place in the hierarchy of planets and stellar objects. Brown dwarfs are more massive than your typical planet, but don't have quite enough mass to sustain the nuclear fusion of hydrogen in its core. The problem is that there is murkiness in the definition of what actually is a ...