Jupiter

Jupiter, the planet.

Its distance from Sol is 5.2 AU (770 million km).

Earth has 10% the diameter of Jupiter, and Jupiter in turn has 10% the diameter of Sol.

Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its barycentre with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's centre.[44] Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive.[7][45] Jupiter's radius is about one tenth the radius of the Sun,[46] and its mass is one thousandth the mass of the Sun, so the densities of the two bodies are similar.[47] A "Jupiter mass" (MJ or MJup) is often used as a unit to describe masses of other objects, particularly extrasolar planets and brown dwarfs.

Somehow, while school had plenty of astronomy and I liked those parts, no one told me astronomy was this interesting!

Theoretical models indicate that if Jupiter had much more mass than it does at present, it would shrink.[49] For small changes in mass, the radius would not change appreciably, and above 160%[49] of the current mass the interior would become so much more compressed under the increased pressure that its volume would decrease despite the increasing amount of matter. As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve.[50] The process of further shrinkage with increasing mass would continue until appreciable stellar ignition was achieved, as in high-mass brown dwarfs having around 50 Jupiter masses.[51]

Although Jupiter would need to be about 75 times more massive to fuse hydrogen and become a star, the smallest red dwarf is only about 30 percent larger in radius than Jupiter.[52][53] Despite this, Jupiter still radiates more heat than it receives from the Sun; the amount of heat produced inside it is similar to the total solar radiation it receives.[54] This additional heat is generated by the Kelvin–Helmholtz mechanism through contraction. This process causes Jupiter to shrink by about 1 mm (0.039 in)/yr.[55][56] When formed, Jupiter was hotter and was about twice its current diameter.[57]