Artist's concept of the brown dwarf Gliese 229 b
Artist's concept of how the brown dwarf Gliese 229 b might appear from a distance of about a half million miles. Glowing like a charcoal ember, Gliese 229 b was discovered in 1995 and is 19 light years from the Earth. This brown dwarf orbits the red dwarf Gliese 229A in the constellation Lepus. Gliese 229A can be seen shining dimly on the upper left. These two dwarfs are about four billion miles apart, about the same distance between Pluto and our sun. Gliese 229 b is believed to be 30 to 40 times more massive than the planet Jupiter, which is massive enough for Gliese 229 b to sustain deuterium fusion, but not enough mass to initiate hydrogen fusion like our Sun. As a result, Gliese 229 b radiates a temperature of only 1, 300o F. It is believed to be two to four billion years old. Despite being so much more massive than the planet Jupiter, the diameter of this brown dwarf is believed to be actually slightly less than Jupiter's Gliese 229 b's greater mass results in its overcoming the internal pressures that sustain Jupiter's greater volume
