Every Type Of Planet Explained in 10 Minutes

追加: 2026-05-22

[00:00:00]Terrestrial planet, the most common rocky planet in the universe. Small, dense, covered in mountains, valleys, and craters. Mercury, Venus, Earth, Mars, these are the ones we know. But across the galaxy, there are trillions of them orbiting stars we will never visit. Some are scorched bare by radiation, some are frozen solid, some sit at exactly the right distance from the star where liquid water could exist on the surface. We call that the habitable zone. Earth is in it. Most rocky planets are not. Super-Earth, nobody knows what the inside of a super-Earth looks like. We have never been to one. We cannot send anything to one. They are larger than Earth, but smaller than Neptune. Some of them may be entirely covered in a global ocean hundreds of kilometers deep with no land anywhere. Others may have atmospheres so thick and heavy that the pressure on the surface would crush anything we could build. The most studied super-Earth is 55 Cancri e.

[00:00:58]It orbits its star so closely that a full year there lasts 18 hours. Its surface temperature exceeds 2,000°.

[00:01:06]The rocks on its surface are likely melting in real time. Mini-Neptune, there are no mini-Neptunes in our solar system. Not one, which means every model we have built to understand them comes from watching them from billions of kilometers away. They sit between super-Earths and ice giants in size.

[00:01:26]Their atmospheres are thick with hydrogen and helium. Beneath that atmosphere, nobody knows what exists.

[00:01:32]Rock, water, something we do not have a name for yet. They are the most common type of planet astronomers find around other stars. And we have no planet like them to study up close. Ice giant Uranus and Neptune are ice giants, but the word ice here does not mean frozen water. It means something stranger.

[00:01:53]Deep inside these planets, the pressure becomes so extreme that water, ammonia, and methane are compressed into a hot, dense fluid that behaves nothing like any substance on Earth. Some models suggest that inside Neptune, it rains diamonds. Actual diamonds. Forming under the pressure and falling toward the core like rain falls toward the ground. We have only sent one spacecraft past Neptune. It flew by in 1989 and kept going. We have not been back since. Gas giant Jupiter is so large that all the other planets in our solar system could fit inside it with the room to spare. It has no solid surface. There is nowhere to land. You would fall inward through layers of gas that get hotter and denser until the pressure crushed whatever entered. Its storm called the Great Red Spot has been raging continuously for at least 350 years. That storm alone is larger than Earth, and Jupiter is not even close to the largest gas giant that exists.

[00:02:51]Hot Jupiter. The first exoplanet ever confirmed around a sun-like star was a hot Jupiter. Astronomers found it in 1995 and did not believe it at first. A planet the size of Jupiter orbiting its star in four days. Closer to its star than Mercury is to our sun. The temperature on its surface exceeds a thousand degrees. It should not exist according to everything scientists understood about how planets form. And yet, the galaxy is full of them. Entire Jupiter-sized worlds that somehow migrated inward from where they formed and now orbit so close to their stars that they are slowly being torn apart.

[00:03:33]Super Jupiter. Some planets make Jupiter look small. Super Jupiters can be up to 13 times the mass of Jupiter. They sit on the boundary between planet and star.

[00:03:42]Below 13 Jupiter masses, you have a planet. Above it, you have something that can ignite fusion and become a brown dwarf.

[00:03:50]Some Super Jupiters are so massive that astronomers debate whether they should be classified as planets at all. Kappa Andromedae b is one of them. It orbits its star at a distance greater than Neptune orbits our Sun, and it is so large it was nearly a star. Ocean planet. Imagine a planet where the ocean is not a thin layer on the surface.

[00:04:10]Imagine a planet that is ocean all the way down. No seafloor, no crust, just water compressed under its own weight into exotic forms that do not exist naturally on Earth. Scientists call these ocean planets or water worlds.

[00:04:25]Some models suggest that in these depths water gets compressed so tightly it becomes a hot solid even at temperatures above a thousand degrees. The pressure prevents it from becoming steam. It just sits there. Solid water at temperatures that would vaporize anything on Earth's surface. Lava planet. Some planets never cooled down.

[00:04:47]They orbit so close to their stars that the surface temperature never drops below the melting point of rock. The entire surface is a global ocean of lava. Active volcanoes everywhere. Magma seas stretching from horizon to horizon.

[00:05:01]The planet 55 Cancri e shows signs of this. Its surface may be entirely molten. Volcanic plumes possibly erupting constantly into an atmosphere of vaporized rock. There is no version of this planet where anything survives.

[00:05:15]It is not a place. It is a furnace.

[00:05:18]Carbon planet. Every rocky planet in our solar system is built primarily from silicon and oxygen. But in parts of the galaxy where carbon is more abundant than oxygen, the chemistry of planet formation changes completely. Carbon planets would have no silicate rocks.

[00:05:36]Instead, their surfaces would be covered in graphite and diamond. Mountains of diamond, plains of graphite, rivers of tar. The sky above them would be hazy with carbon compounds, no oxygen, nothing breathable. A geologist from Earth dropped onto one would not recognize it as a planet at all, just a dark alien world built from chemistry that does not exist anywhere near us.

[00:06:01]Diamond planet. In 2012, astronomers announced a planet that may be made largely of diamond, PSRJ1719-1438b.

[00:06:14]It orbits a pulsar. It is twice the mass of Jupiter. Its density suggests that it is composed primarily of crystalline carbon, diamond. An object twice the mass of Jupiter made of compressed carbon orbiting a dead spinning star completing one orbit every 2 hours. The most valuable object in the universe, if value meant anything at that scale.

[00:06:38]Dwarf planet Pluto was a planet for 76 years. Then in 2006, astronomers voted and took the title away, not because Pluto changed, because our definition did. A dwarf planet orbits the sun. It has enough mass for gravity to pull it into a roughly round shape. But, it has not cleared the other objects from its orbital path.

[00:07:03]Pluto shares its neighborhood with thousands of other objects in the Kuiper Belt, so it was reclassified. Pluto did not move. We just understood where it lived for the first time. There are likely hundreds of dwarf planets in our solar system that we have not yet found.

[00:07:18]Rogue planet. There are planets drifting through the galaxy with no star, no light, no warmth, just cold dark worlds moving silently through interstellar space. They formed around stars and were ejected, or they formed alone in the darkness between stars entirely without a sun. Some estimates suggest there could be billions of rogue planets in the Milky Way alone, more rogue planets than stars, entire worlds in permanent darkness. If any of them have subsurface oceans kept liquid by internal heat from radioactive decay, something could theoretically be alive down there right now, in the dark, with no sun, with no idea that stars exist. Pulsar planet.

[00:08:01]The first exoplanets ever discovered orbit a pulsar, a dead star.

[00:08:06]A rapidly spinning neutron star that emits beams of radiation sweeping through space like a lighthouse. These planets survived a supernova explosion.

[00:08:15]Their original star exploded and destroyed everything around it, and somehow these planets survived. They now orbit the remnant of that explosion receiving constant blasts of radiation instead of light. They are bathed in it.

[00:08:29]There is no atmosphere that could survive that environment. No surface chemistry, just bare irradiated rocks spinning around a dead star at the edge of physics. Chthonian planet, a hot Jupiter that got too close. Over billions of years, the star's heat and gravity stripped away the atmosphere layer by layer. All that gas, gone. What remains is the bare core, a dense rocky remnant of what was once a giant planet. Scientists believe these objects may explain certain rocky planets found in very close orbits around their stars.

[00:09:03]They were not born rocky. They were stripped. Entire atmospheres lost to stellar radiation over timescales so long the human mind cannot process them.

[00:09:13]The planet did not die, it was just reduced to something unrecognizable.

[00:09:17]Goldilocks planet. Not too hot, not too cold, the right distance from the right star for liquid water to exist on the surface. These are called Goldilocks planets or habitable zone planets. Earth is one. Kepler-186f may be another. It sits in the habitable zone of a red dwarf star 500 light years away. It is roughly Earth-sized. Whether it has water or an atmosphere or anything at all, we do not know. We detected it by watching its star dim slightly as it passed in front of it. That is all we have. A shadow, a slight dimming of a distant star, and the possibility that something could be alive there right now looking up at their sky. Circumbinary planet. Some planets orbit two stars, not one, two. The sky above them would have two suns rising and setting at different times and different angles.

[00:10:09]Their seasons would be chaotic because the gravitational pull of two stars creates orbits that shift and wobble over time. Kepler-16b is one of them. It orbits two stars that orbit each other.

[00:10:21]Scientists used to think stable orbits around binary stars were impossible for planets. Then they found one. Then they found more. The galaxy does not ask for permission before doing things we think are impossible.

[00:10:34]Extragalactic planet. In 2018, astronomers announced a candidate planet outside the Milky Way entirely in the galaxy Messier 51, the Whirlpool Galaxy, 28 million light years away. They detected it the same way.

[00:10:50]A shadow, a dimming of an X-ray source as something passed in front of it.

[00:10:55]We cannot confirm it. We cannot study it. We cannot send anything toward it.

[00:11:00]By the time any signal we send reaches, it the sun will be long dead. But the mathematics says something is there, a planet in another galaxy orbiting a star we will never see up close, the most distant world ever detected, and almost certainly not the last. You have just seen every type of planet that exists or that we think exists. Some of these worlds are sitting in databases right now waiting for a name. Some of them we will never reach. Some of them we will never even see. Just a shadow, a number in a spreadsheet, a slight dimming of a distant star that told us something's out there. The universe has more planets than it has grains of sand on every beach on Earth combined, and we have named maybe a few thousand of them. If this video made you feel small, that is correct. If it made you curious about what else is out there, subscribe because we are just getting started.