Ethan K

April 29, 2021

The spherical things around other hot and spherical things

Planets are very interesting. Not just because we live on one, but because of their interesting formation, interesting types, interesting collisions, different interesting ways to observe them, and interesting deaths. So, let’s dive in, shall we?

Formation

Most planets formed the same way: Through collisions and gravity around a star. All planets started the same: as a boring cloud of gas. This gas doesn’t have enough gravity to join together; instead, they kind of just sit there. So, how did these gigantic clouds of dust become planets? The answer: Dust bunnies.

You have almost certainly experienced electrostatic force in your life, it’s the force that, when you rub a balloon on something fluffy, makes things stick to the balloon. Well, the same force applies in forming these dust bunnies. Each little piece of dust has some tiny force on each other, and they eventually clumped together into little dust bunnies. So how did these dust bunnies turn into rocks?

This same electrostatic force makes particles rub up against each other and create some electricity. This forms lightning (albeit small) and when this lightning hits a dust bunny, it heats it up so much that the dust bunny turns into rocks. Now, all of these rocks STILL don’t have enough mass to make gravity kick in. So, as all the rocks are orbiting a star, they are only getting bigger through random collisions. Once many of these now asteroids have enough mass, gravity takes over, and the big asteroids pull in any other ones near it, becoming protoplanets.

 These protoplanets are now big enough to become circular in size, as the gravity of the planet collapses any mountains and pulls them in, becoming roughly circular. And while this is all happening, a protosun is forming, basically in the same process as everything else, but just on a much larger scale.

And that is how most planets formed. Now, let’s talk about different types of planets.

The Different Types of Planets

Planets are like a family (a really, really, REALLY big family). And like every family, there are the nice ones, the normal ones, the small ones, and the weirdos. Let’s talk about the normal planets first.

Most planets live around a star. The two types of planets are the rocky planets and the gas giants. The rocky planets are normally closer to the star, and the gas planets are farther, because gas can’t stay near the star because of the intense solar radiation. Take our solar system, for example. Our solar system has four rocky planets close to the sun (Mercury, Venus, Earth, Mars) and four gas giants far from the sun (Jupiter, Saturn, Uranus, Neptune). But of course, there are the weird ones in this group.

In the 1900s, the hunt for discovering new planets around other stars was on. Astronomers were looking for any little wobbles in other star’s orbits, meaning there was a planet around the star, pulling the star with its gravity. And on the sixth of October, 1955, they found the first exoplanet 45 light years away, orbiting the sun-like star 51 Pegasi (abbreviated 51 peg). This planet (dubbed 51 Pegasi b) is a gas giant, orbiting 4,125,000 km away from its star, meaning that the orbital period is about four days, also meaning that the gas giant is very, very hot. But the gas giant couldn’t have formed there, so how did it get there?

Planetary migration is probably what happened with 51 Pegasi b. Gas giants have a lot of dust and gas to clear before their orbit is free of debris. And sometimes, the gas’s friction and drag can slow down the planet enough to make the orbit tighter. And so it goes, each time the planet orbits the star, it gets slower and falls in closer, until it gets close enough to have a really “bad time.” In more scientific words, it will get into the “no gas” zone, where all the gas is blown away by the star’s solar wind. 

And since 1955, over 400 of these “hot Jupiters” have been found! So those are the types of planets, but how do they die?

Death of a Planet

Now, there are some planets which are very unlike other planets, but here is the general concept of the normal ones: After the star runs out of fuel, the star will either go kablooey, or it could just expand and blow out its outer layers. If the star goes kablooey (i.e. the star undergoes a supernova), the planets around the star will probably be disintegrated, or ejected from the force. 

If the star blows out the outer layers (like what would happen with our sun), most planets (except for the ones really close) will survive. However, the gravitational force of the remnant of the star (the core of the star, called a white dwarf) is much weaker than the star that just died. So most planets will be flung out of the system. 

But that’s not always how planets die. Some planets are ejected from the system when they are just being born. When a star forms and creates protoplanets, these protoplanets interact gravitationally, and some are flung out, and others are flung into the star. This might be what happened to a gas giant about 2-41 times the mass of Earth. In the very early solar system, the solar system was a chaotic place, and some plants were flung into very long and elliptical orbits. One of these planets is the mysterious planet 9 (i.e. planet X) which may or may not have existed, and was flung into the outer reaches of the solar system, causing disturbances in the outer solar system and flinging dwarf planets into highly elliptical orbits.

Conclusion

In conclusion, planets are very mysterious bodies. They have a very violent formation, and have a very violent ending. Let’s learn more about these strange planets!


1in other words, -2, because 2 – 4 = -2