- The massive gas giant Jupiter may have become a star in the earliest days of the solar system.
- If Jupiter had become a star, the chances of Earth hosting (or even existing) life would be slim.
- You can find more stories on the BGR homepage.
Jupiter is the mighty king of our solar system. It is by far the largest and most massive planet, and the swirling storms that dominate its atmosphere make it instantly recognizable. It is big. So big, in fact, that it is actually not crazy to imagine that our solar system trembles so much that Jupiter grows large enough to become a star.
In a new piece Universe todayPaul Sutter suggests an interesting thought experiment that uses our knowledge of Jupiter and what scientists have learned about star formation. The short version of the story says that we should be very happy that Jupiter is not bigger.
Stars become stars because of their mass. Star systems arise from gas and dust clouds. Gravity works magically and finally this matter begins to collect. The larger the central object, the greater its appeal. It grows exponentially and if there is enough matter nearby, a star can be born.
When an object collects enough mass, the pressure inside becomes so strong that it is capable of nuclear fusion. It ignites and depending on how massive the object is, it becomes a certain kind of star.
As we know, Jupiter is fairly large, but not large enough to trigger a fusion at its core. In fact, it would have to be about 20 times as massive as it is to become a class of stars known as the red dwarf.
It is believed that the Kuiper belt – a broad disc of material that surrounds our solar system – now contains only a tiny fraction of the mass than it used to. How much of this mass was there in the inner solar system? We don’t know, but when a planet the size of Jupiter devoured material at an exponential rate, it is not impossible to believe that it could continue to feed very well until it reached the size of a star.
Binary systems in which two stars orbit can still house planets. Astronomers have already discovered such systems, so we know they exist. Would the Earth, if it existed at all, have been lucky in orbit? Would a two-star system have given a planet in our system the conditions it needs for life?
We’ll never know, but we can at least be glad that Jupiter stopped eating when it happened.