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Could Jupiter Become a Star?

Last Reviewed and Updated on June 24, 2022

Jupiter is the largest planet in our Solar System and it’s the second-largest astronomical body, the Sun being the only thing more massive and larger. This gas giant is often referred to as a failed star so you might be wondering, could Jupiter become a star at some point in the future? Let’s get the answers.

About Jupiter

Jupiter is the 5th planet in our Solar System and by far the largest planet. It accounts for about 0.095% of all of the mass in our Solar System. This is still more than all of the other planets combined.

It is a gas giant, meaning it’s a large planet with relatively low density and is mostly composed of hydrogen and helium.

Looking at the composition alone, Jupiter is very similar to the Sun.

Also read: fun facts about the planet Jupiter

Are there stars smaller than Jupiter?

So now we know the composition of Jupiter is similar to that of a star. Now let’s talk about the size. If you compare Jupiter to our Sun, this large planet will look tiny as the Sun is about 10 times wider. But there are many stars in the universe and they come in many sizes.

If we look at the first stages (main sequence) of the star’s life cycle, Red dwarfs are the smallest stars. The star SSSPM J0829-1309 (we know, not a fancy name) has a radius of 61.300 km, which makes it smaller than Jupiter (radius 69.911 km). There are quite a few that are about the same size, and many are still to be discovered.

Could Jupiter become a star?

So now you know that Jupiter has a similar composition to that of a star and that there are stars that are smaller or the same size as Jupiter. What does this mean? Could Jupiter become a star or is there something this gas giant is still missing?

Turns out, that Jupiter is missing something, and it is missing a lot of it. This planet simply does not have enough mass to fuse hydrogen into helium. As there isn’t enough mass, the core temperature and pressure aren’t high enough to make this process happen.

It would need to be more than 80 times more massive in order to sustain nuclear fusion (hydrogen converted into helium).

It would need more than 10 times the mass it has to be a substellar object (a substar). These objects might have hydrogen fusion temporarily but can’t sustain it.

So Jupiter will never start a thermonuclear reaction in its core that would turn it into a star, it’s just not massive enough.

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