What's The Largest Planet In The Universe?

Jupiter is the largest planet in our Solar System, but what is the maximum size of a planet?

If you put too much mass into a single object, the core will fuse lighter elements into heavier ones.

At roughly eighty times the mass of Jupiter, you'll have a true star capable of converting hydrogen into helium.

Lower than that, at roughly 14 times the mass of Jupiter, you'll start deuterium fusion, in which leftover Big Bang fuel slowly self-generates its own energy.

Brown dwarfs, on the other hand, are physically smaller than the largest gas giants.

The atoms inside large planets begin to compress so severely above a certain mass that adding more mass actually shrinks your planet.

This occurs in our Solar System, which explains why Jupiter has three times the mass of Saturn but is only 20% physically larger.

However, in many solar systems, planets are composed of much lighter elements and lack large, rocky cores.

As a result, before becoming stars, the largest planets can be up to twice the size of Jupiter.