Jupiter Is Not a Failed Star


Image taken by Micheal Larwood, amateur astronomer

It’s often said by educators that Jupiter is a failed star, that if it only had a little bit more mass it would be a second star in the Solar system. Then why is it that we are finding gas giant planets about 10 times its mass orbiting other stars? Now that doesn’t seem terribly much bigger than Jupiter until you realize just how large Jupiter really is. It has a volume of 1.43 x 10^15 (that’s 10 with fifteen zeroes) cubic killimeters. Over 1,300 Earths could fit inside it and it has a gravity well that extends so far that Jupiter prevented the asteroid belt from coalescing into a planet. It is even theorized that the gas giant may have allowed life to form on Earth (I may have an additional write up on that). But I digress.

How big of a gas giant can you get before there is enough mass to begin core fusion? Brown dwarfs are much more massive than Jupiter could ever dream of being but are still not really stars. They don’t fuse hydrogen. They sort of glow a bit in the red end of the spectrum, which is why they’re so hard to spot. They’re close, but not quite close enough. If anything, these brown dwarfs are the real failed stars, not Jupiter. In order to really shine like a star you need approximately 80 times Jupiter’s mass to really kick off that core fusion… the mass of a red dwarf star. So for there to be a Jupiter that acts like a second star in the Solar system we would need another 79 Jupiters worth of mass.

So, why is it that astronomers, experts in the field, still say that Jupiter is a “failed star”? I don’t buy the whole popularization of astronomy that science centers and planetaria use. I know the general public is ignorant of astronomical phenomenon and I get it that they may choose to be so. However, claiming inaccuracies like this is not doing the field any favours. You may capture some initial interest but you will find that you will more often lose that budding little amateur astronomer when they find out the truth. Their conclusion may be, “scientists lie”. Scientists lie? Where have I heard… ah yes… climate change denial. We are all familiar with what happened when scientists were undermined by politicians, corporations and shills of the oil industry. But I hear you… that wasn’t the fault of the scientists. Yet if you think about it you may realize that if much of the world reacted the way they did by denying the science behind climate change, how do you think people will react when a blatant misrepresentation of facts is so consistently and repeatedly perpetrated, no matter how small that “lie” may be? Exactly. Let’s stop trying to popularize science and discovery by issuing misleading/false facts and stretched truth. This is science… not politics.