Every Type Of Moon Explained in 10 Minutes

[00:00:00]Collision moon. Around 4.5 billion years ago, Earth may have been hit by another planet roughly the size of Mars. Imagine two balls of melted rock smashing together at thousands of chemisters per hour. Huge pieces of Earth and the other planet were thrown into space, creating a glowing ring of broken rock around our world. Over time, gravity pulled those pieces together. They joined into larger and larger clumps until they became the moon. This collision also changed Earth.

[00:00:26]The moon now pulls on our oceans to create tides and help stop our planet from wobbling too wildly. So, the calm moon lighting up the night sky may actually be the scar left behind by the worst crash Earth ever survived. But the next moon was not made by its planet. It was stolen. This is a captured moon. A captured moon begins as a separate world before a planet traps it with gravity.

[00:00:47]Imagine throwing a ball past someone.

[00:00:49]Usually, it flies past them and keeps going. But if they grab it at exactly the right moment, the ball is no longer free. Something similar may have happened to Triton, Neptune's largest moon. Triton probably began far away from Neptune as a small frozen world, similar to Pluto. Then it passed too close. Neptune's gravity grabbed it and forced it into orbit. Most large moons were born beside their planets, so they travel in the same direction the planet spins, like runners moving around the same track. Triton does not. It circles Neptune in the opposite direction. That backwards orbit is the clue. Triton probably did not form there at all. It was once a free world until Neptune's gravity stole it. And moons do not only orbit planets. Some orbit objects that look like ordinary space rocks.

[00:01:32]Introducing the asteroid moon. An asteroid moon is a tiny moon orbiting a larger asteroid. Asteroids can gain moons after a collision knocks pieces away. If one piece does not fly off fast enough, gravity keeps it nearby. Imagine a boulder floating through space with a smaller stone slowly circling around it.

[00:01:49]That is basically an asteroid moon. The first one ever discovered was Dactyl, a small moon orbiting an asteroid called Ida. Some asteroid moons are only a few hundred meters wide. You could drive across one in a few minutes. One of the most famous is Dorphos. In 2022, NASA deliberately crashed a spacecraft into it and changed its orbit. But move one of these tiny moons inside a planetary ring and it starts leaving giant tracks behind it. This gives us a ring moonlet.

[00:02:16]A ring moonlit is a tiny moon buried inside one of Saturn's rings. You might think Saturn's rings are solid, but they are actually made from billions of separate pieces of ice all traveling around the planet together. Now, imagine placing a small moon inside that moving river of ice. As the moon travels, its gravity pushes nearby pieces out of the way. But the moon is too small to clear a complete gap around Saturn. Instead, it creates two short openings, one slightly ahead of it and one slightly behind. From above, those openings look like the two blades of a propeller. The moon itself may be smaller than a town, but the shape it creates can stretch for hundreds of kilometers. Sometimes scientists cannot even see the moon.

[00:02:54]They find it by spotting the gap moving through the ring. Make that moon slightly larger, and it can clear a path all the way around Saturn. That creates the next type of moon, a shepherd moon.

[00:03:05]A shepherd moon is a moon that helps keep a gap in a planetary ring open.

[00:03:09]Imagine a tiny sheep dog running around the edge of an enormous herd. It never touches the animals, but it keeps anything that wanders too far from crossing the boundary. Saturn has a moon called Pan that does something similar.

[00:03:20]Pan travels inside a gap in Saturn's rings called the Anky Gap. Whenever ring particles drift too close, Pan's gravity nudges them back toward the edges. The previous ring, Moonlit, only created two short openings near itself. Pan helps maintain one clean gap that stretches all the way around Saturn, and Pan is only around 28 km wide. The next moons do something even stranger. They share the same orbit with other moons. This is a Trojan moon. A Trojan moon is a small moon that shares the orbit of a larger moon while staying safely ahead of it or behind it. Saturn has a perfect example.

[00:03:53]One of its larger moons is called Teus.

[00:03:56]A smaller moon called Telesto travels ahead of it while another called Calypso follows behind. Picture three cars driving around the same circular track at the same speed. One stays in front, one in the middle, and one behind.

[00:04:07]Gravity keeps the three moons spaced apart, so they never catch each other or collide. Most moons have an orbit to themselves. Trojan moons safely share theirs with something larger, but the next pair gets close enough to swap places. This is a co-orbital moon.

[00:04:21]Co-orbital moons are two moons that share almost the same orbit. Saturn has a pair called Janice and Epimetheus.

[00:04:28]Their paths are only around 50 km apart.

[00:04:30]It's like having two cars racing around the same track in lanes so close they nearly touch. Every four years, the inner moon catches up to the outer one, but instead of crashing, their gravity pushes them into opposite lanes. The inner moon moves outward, the outer moon moves inward. They swap places, then separate again. The next moons are far less organized. This is a chaotic moon.

[00:04:52]A chaotic moon spins and tumbles without following a simple pattern. Most large moons keep the same side facing their planet, just like ours, which is why we always see the same face from Earth. But Pluto's small moon Nyx does not behave that way. Nyx is oddly shaped and it is pulled by both Pluto and Pluto's large moon Cheron. Those changing forces make it tumble through space like a badly thrown rugby ball. Imagine standing on the surface. The ground slowly rolls beneath you. The sun may rise from one direction, disappear, then return somewhere completely different. So far, we have focused on how moons move. The next moons are entire alien worlds.

[00:05:28]Introducing the volcanic moon. A volcanic moon is a moon with so much heat inside it that its surface is covered in active volcanoes. Jupiter has one called Io. Io orbits so close to Jupiter that the planet's gravity constantly stretches and squeezes it.

[00:05:43]Imagine repeatedly crushing and releasing a rubber ball. That movement creates heat inside the moon. Io's surface can rise and fall by around 100 m, the height of a 30story building. The heat melts rock and powers hundreds of volcanoes. Io should have frozen solid billions of years ago. Instead, Jupiter keeps squeezing it back to life. On Io, gravity creates fire. Inside the next moon, it keeps water from freezing.

[00:06:06]Introducing the ocean moon. An ocean moon is a moon with liquid water hidden beneath a frozen surface. Jupiter has one called Europa. From the outside, Europa looks like a giant cracked snowball, but beneath the ice may be an ocean containing around twice as much water as all of Earth's oceans combined.

[00:06:23]Jupiter's gravity constantly bends the moon, creating enough heat to stop that ocean from freezing solid. That heat could also create underwater vents on the seafloor. On Earth, similar vents support life without any sunlight. So, beneath Europa's frozen surface, simple organisms may be able to survive in complete darkness. From space, Europa looks dead. Underneath, it may be one of the best places to search for alien life. The next moon puts its environment directly above the surface. This is a weather moon. A weather moon is a moon surrounded by a thick layer of gas. That gas can create clouds, wind, rain, and full weather systems. Saturn has one called Titan. Titan is Saturn's largest moon, and it is wrapped in a thick orange atmosphere. If you stood there, you would see clouds, rivers, lakes, and rain. But the rain is not water. Titan is so cold that liquid methane falls from the sky instead. Imagine gasoline behaving like water does on Earth. It evaporates, forms clouds, rains onto the ground, and collects inside lakes.

[00:07:21]larger than some countries. Its atmosphere is even thicker than Earth's.

[00:07:24]You would still need a space suit though because there is no oxygen and the cold would freeze you almost instantly. But apart from that, Titan looks strangely familiar. It is like Earth rebuilt inside a freezer using different materials. The next moon is actually larger than a planet. This is a planet-sized moon. A planet-sized moon is a moon large and complex enough to resemble a full planet. Jupiter has one called Ganymede. Ganymede is the largest moon in the solar system and it is even wider than Mercury. Place the two side by side and the moon would look bigger than the planet. But Ganymede is not just large. It has a metal core, a hidden ocean, and even its own magnetic field. That magnetic field forms an invisible shield around the moon, similar to the one protecting Earth. No other known moon can do this. If Ganymede orbited the sun instead of Jupiter, we would almost certainly call it a planet. The only thing making it a moon is its location. The final three moons push that definition even further.

[00:08:16]Introducing the doomed moon. A doomed moon is a moon whose orbit is slowly carrying it towards its own destruction.

[00:08:23]Mars has one called Phobos. Imagine standing on the Martian surface and looking up. Phobos would race across the sky in just a few hours, completing three full orbits around Mars every day.

[00:08:33]But each orbit is also a tiny step downwards. Mars' gravity pulls Phobos around 2 cm closer every year, which is about the width of your thumbnail. That sounds harmless, but give it millions of years, and those tiny steps become a one-way staircase towards the planet.

[00:08:48]Eventually, Phobos will move so close that Mars' gravity becomes stronger than the moon can survive. It could crash into the surface, or it could be stretched and ripped into millions of pieces before it ever gets there. And those pieces may not fall immediately.

[00:09:01]They could spread around Mars, forming a giant ring where the moon used to be.

[00:09:04]Phobos is not simply orbiting Mars. It is slowly being turned into part of it.

[00:09:09]The next moon is so large that calling it a moon barely feels correct. This is the double world moon. A double world moon is a moon so massive compared with its parent that both worlds orbit the space between them. Far beyond Neptune is a dwarf planet-sized world called Orcus. It has a large moon called Van.

[00:09:26]Van has around 16th the mass of Orcus, making it unusually heavy for a moon.

[00:09:31]It's like having two people of different sizes holding hands and spinning around in a circle. The larger person moves less, but neither person stays in the center. Orcus and Van do the same thing.

[00:09:41]Both worlds circle a shared point floating outside Orcus. Every moon so far exists inside our solar system. The final type orbits planets around other stars. This is an alien moon. An alien moon is a moon orbiting a planet around another star. We have already found thousands of distant planets and many of them are likely surrounded by moons. The problem is spotting one. Imagine trying to see a fly beside a car from thousands of kilometers away. The planet is already difficult to detect. A moon beside it is almost invisible.

[00:10:11]Astronomers have found a few possible examples, but none has been fully confirmed, which means the first true alien moon could be unlike anything in our solar system. It could be larger than Earth. It could have oceans, an atmosphere, or even the right conditions for life. And if it is large enough, it could hold a smaller moon of its own. A submoon. A moon orbiting a moon, orbiting a planet, orbiting a star. We have never found anything like it, but somewhere in the galaxy, entire layers of worlds may be circling other worlds.

[00:10:38]If you made it this far into the video, comment moon down below. Don't forget to like, subscribe, and be sure to check out my other videos. There's a whole playlist full of them in the description below.