How Can Jupiter Have 79 Moons While Other Planets Have None?

around Jupiter. Scott S. Shepherd of the Carnegie Institute for Sciences was leading a search for new objects in the distant Kuiper Belt, an enormous ring of debris that lies beyond Neptune. Shepherd and his colleagues decided to take a break from their primary research goal and observed Jupiter for a while. That's how they wound up standing on Galileo's shoulders.

In sixteen ten, the great astronomer Galileo Galilei noticed four heavenly bodies that appeared to revolve around Jupiter, named Io, Europa, Ganymede, and Callisto. These are Jupiter's biggest moons by far, and they were the first to be discovered. As stargazing technology grew more sophisticated, it became clear that the quartet had lots of company. Shepherd's team just brought the total number of identified Jovian moons, that is, moons that revolve around Jupiter,

up to seventy nine. No other planet in the Solar System comes close to that figure. Saturn is the runner up with its sixty two verified moons, while Urinas boasts twenty seven and Neptune has fourteen. Mars, our beloved next door neighbor, possesses two satellites, Demos and Phobos. And if that's making you feel insecure about Earth's lonely single moon, at least you could take solace in the fact that

Mercury and Venus are totally moonless. According to the astronomer Neil F. Corman's, if planet Earth had two moons instead of one, our knights would get brighter because there would be twice as much sunlight reflecting off of lunar surfaces. Also would see significantly higher tides, rendering many coastal areas uninhabitable. There's a reason why Jupiter has so many satellites while other planets, Ours, for instance, have so few, or a few reasons really, but it all comes down to gravity.

Astronomers divide the planets within our Solar System into two categories. Mercury, venous, Earth and Mars are so called terrestrial or inner planets, while Jupiter, Saturn, Uranus, and Neptune have been classified as gas giants, also known as outer planets. The size gap between those factions is quite considerable. Although Uranus is the smallest outer planet, it's still fifteen times more massive than Earth,

which is the largest of the inner planets. But none of the other planets can compete with Jupiter in terms of sheer bulk. You'd need more than three hundred duplicates of our puny home world to equal Jupiter's colossal mass. Now, as Isaac Newton observed, there's a positive correlation between the mass of an object and the strength of its gravitational field. Because the gas giants are so massive, they're able to attract more satellites. That's not the only reason why planets

like Jupiter have such large moon collections. Our Solar systems gas giants are relatively far away from the Sun. In contrast, some stars have massive Jupiter like planets called hot jupiters. Basically, these are gas giants that orbit in close proximity to their stars. Imagine if Saturn switched places with mercury. A twenty ten paper by French astronomer effect He in the Money argues that hot jupiters have few, if any moons. These planets are thought to originate in distant parts of

their solar systems, and then migrate inwards. Along the way, their moons get caught in a game of celestial tug of war. Gas Giants may be big, but stars are much bigger. As such, they've got far stronger gravitational fields, so when a hot jupiter gets too close to its star, the star will eventually steal its moons. Distance offsets this ability. The further you travel from the Sun, the weaker its gravitational pull on you becomes. Are For, if Naumali is correct,

then our Jupiter has seventy nine moons and counting. Because it's a ridiculously massive planet that's far enough away from the Sun to avoid lunar theft. Jupiter's moons are hardly a monolithic family. A few of them have quirks that are well known to astronomy enthusiasts. Io is loaded with active volcanoes, there's a hidden ocean on Europa that might harbor alien life, and at two thirds the size of Mars. Ganymede is the biggest satellite in the entire Solar System.

These three moons, along with Kalisto, probably formed in tandem with Jupiter itself. The big planet likely started out as a disc of gases and dust that eventually became the gas giant we know today. While Jupiter took shape, some of the materials swirling around it coalesced into the four moons. Galileo spied in sixteen Saturn may have helped move the process along. It's also been hypothesized that early Jupiter had a number of failed moons that were pulled into and

absorbed by the huge planet. It's other satellites weren't necessarily homegrown. Scientists think that many of Jupiter's moons started out as drifting chunks of rock that became ensnared by the planet's gravitational pull, And we also have to talk about lunar behavior. Many of the Jovian moons orbit in the same direction in which Jupiter spins, but there are those that go the opposite way, including nine of the new moons discovered by Shepherd and his colleagues. With so many bodies revolving

in different directions. Collisions are inevitable. Moons that crash into one another might well be destroyed in the process. Just as Jupiter acquires new moons, it's finding ways to lose some of the older ones. Today's episode was written by Mark Mancini and produced by Tyler Clang. Brain Stuff is production of I Heart Radio's How Stuff Works. For more on this and lots of other far from monolithic topics,

visit our home planet, how stuff Works dot com. And for more podcasts from my heart Radio, visit the heart Radio app, Apple Podcasts, or where every listen to your favorite shows. H