Is Jupiter a Failed Star?

Authored by astronomy.com and submitted by clayt6

The brilliant planet Jupiter dazzles anyone with a clear sky. Roman observers named Jupiter after the patron deity of the Roman state following Greek mythology, which associated it with the supreme god, Zeus. But when Galileo turned his telescope skyward in 1610, Jupiter took on new significance. Galileo discovered the planet’s four principal moons — and witnessed the first clear observation of celestial motions centered on a body other than Earth.

Astronomers recognized Jupiter as the largest planet in the solar system long before any spacecraft provided detailed exploration. The planet’s mammoth size — 88,846 miles (142,984 kilometers) at the equator — holds 2.5 times the mass of all the other planets combined. This makes Jupiter the most dominant body in the solar system after the Sun. The planet’s volume is so great that 1,321 Earths could fit inside it.

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Jupiter is a magnificent example of a gas giant planet. It has no solid surface and is composed of a small rocky core enclosed in a shell of metallic hydrogen, which is surrounded by liquid hydrogen, which, in turn, is blanketed by hydrogen gas. By count of atoms, the atmosphere is about 90 percent hydrogen and 10 percent helium.

beepbop24 on September 16th, 2019 at 18:50 UTC »

“Jupiter isn’t a failed star, it’s just a very successful planet.” -Phil Plait

stos313 on September 16th, 2019 at 17:35 UTC »

In my college Astro class, I remember my prof saying, “the solar system is 99.9% the sun and .1% Jupiter”. Heh

Lm0y on September 16th, 2019 at 17:07 UTC »

Fun fact: Jupiter is about as big as planets can possibly be. More mass just gets compressed by gravity. That's why Saturn, despite being a fraction as massive as Jupiter, is almost as big. Brown dwarf stars are all about the same size as Jupiter too.

Fun fact 2: Brown dwarf stars would probably appear magenta to the naked eye, if it were possible to get near enough to see one.