yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

The solar system | Earth in space | Middle school Earth and space science | Khan Academy


4m read
·Nov 10, 2024

The Earth isn't flat, but the solar system is about 4.6 billion years old. The material that makes up our solar system was in the form of a nebula, which is pretty much a big cloud of gas and dust in space. Gravity flattened this material into a disc, like this one, and then pulled everything towards the center. Eventually, the pressure became so great that a star was formed: the Sun.

The remaining dust and gas particles collided with each other and eventually formed larger objects like Earth. Together, the Sun and all the objects in space that its gravity keeps in orbit make up our solar system. We call the biggest objects that orbit the Sun planets. Our solar system has eight of them: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

These eight planets are divided by the asteroid belt. Asteroids are rocks that orbit the Sun that are much smaller than planets, and they're made up of nickel and iron. Unlike the planets, most asteroids aren't round. Beyond Neptune is the Oort Cloud, a space at the very edge of the solar system that's filled with comets, which are like space snowballs that are made up of ice and dust. Sometimes comets enter the inner part of our solar system and can even be seen from Earth, with long tails of ionized gases.

One of the most famous comets is Haley's Comet, which only comes near Earth every 75 years or so. Be on the lookout for it in 2061. The four planets on the side of the asteroid belt closer to the Sun are called the inner or terrestrial planets. The word "terrestrial" comes from the Latin word for Earth.

Terrestrial planets have solid, rocky surfaces, thin atmospheres, few or no moons, and no rings. The closest planet to the Sun is called Mercury. It's the smallest planet in the solar system, and it doesn't have any moons. Next, there's Venus. It's the closest planet to Earth, and like Mercury, it doesn't have a moon. Venus shines bright in the sky like a star; it's about the same size as Earth, but you wouldn't want to live on it.

It's the hottest planet in the solar system, and its atmosphere contains an unbreathable mixture of carbon dioxide and sulfuric acid. Next is our home planet, Earth. Earth is the only planet known to have life on it. The last terrestrial planet in our solar system is Mars. Mars has a very thin atmosphere of carbon dioxide, and it has two moons. We've sent robots called rovers to Mars in order to explore the planet's surface.

The planets on the other side of the asteroid belt are called the outer planets, and unlike the inner planets, they're not made out of rock. Instead, they're made out of gases and liquids, and they have many moons and rings. They're much, much colder and much, much bigger than the terrestrial planets. For instance, the planet Jupiter is so big that it could fit about 1,300 Earths inside of it.

We call Jupiter a gas giant because, you guessed it, it's giant and made up of gas. Its atmosphere is mostly made up of hydrogen and helium. It has more than 50 moons; one of Jupiter's moons, Ganymede, is bigger by volume than the planet Mercury. Jupiter spins really fast on its axis. This means that a day on Jupiter is a little less than 10 hours long.

If you travel another 650 million kilometers or so from Jupiter, you'd see Saturn, another gas giant. In 1610, Galileo Galilei became the first person to see Saturn's rings. Because his telescope wasn't strong enough, he couldn't tell what they were, and he thought it looked like the planet had ears. Even though Saturn's rings look smooth from a distance, they're actually made out of rocks and pieces of ice that orbit the planet because of Saturn's gravitational pull.

The next planet is called Uranus; it's the sideways planet. Uranus has smaller rings than Saturn does, and it's so far away from the Earth that we can only see it with a telescope. Even farther away from Earth is the big and blue planet Neptune. Because Neptune is so far away from the Sun, it's really cold here. The average temperature of Neptune is about negative 214 degrees Celsius. It's also the windiest planet in our solar system, with winds going at more than 2,000 kilometers per hour. So if you ever visit, bundle up!

The planets don't all take the same amount of time to orbit the Sun. For example, it takes Jupiter 12 years to orbit the Sun just once. In the same amount of time, Mercury has already orbited the Sun nearly 50 times, and Neptune hasn't even made it around once. Although humans have visited the Moon, we haven't built a rocket ship that can allow us to visit our neighboring planets yet.

We've been able to learn more about our solar system by using other kinds of technology. Humans have built incredible telescopes that allow us to see into our solar system and beyond, and we've sent probes to other planets and captured stunning images. Even with all this research, scientists are still learning new things about our solar system and its place in the rest of the universe. So maybe one day, you can help solve some of the solar system's great mysteries too.

More Articles

View All
Jungle Pilots are Superheroes - Smarter Every Day 152
Hey, it’s me Destin. Welcome back to Smarter Every Day. I’m currently sitting in an airport with my oldest son and we’re on our way to Idaho. Destin: Where does Superman get his superpowers? Son: Krypton. Destin: The planet Krypton. What about Batman? Ho…
The Better Customer–Startups or Big Enterprise?
I just want to turn my startup into like a real-time strategy game where I can sit at my computer and click on things and watch numbers go up. If I can do that and just sit on the couch and have people bring me food while I click things, we’re in good sha…
Warren Buffett's 7 Rules to be a Great Investor
Price people are really strange on that. I mean, they cause most people, most, most, your listeners are savers, and that means they’ll be net buyers, and they should want the stock market to go down. They should want to buy at a lower price, but they’ve g…
Pinstriping my Lotus Exige S240 for $7
What’s up? You think Mornington granted today is going to be a fun game? I’m all the ways of red clay and my God, I wore last week judgment. Lots of luck, and I got this off of eBay, like six dollars in China. What it is, it’s the final lightning pink. I …
Subtracting integers find the missing value | 7th grade | Khan Academy
So if I were to ask you if I were to tell you that negative 3 minus blank is equal to negative 4, can you pause this video and figure out what this blank is? All right, now let’s do this together, and I’m going to do this by drawing out a number line bec…
10 Stocks the Smart Money is Buying Right Now
[Music] Hey guys and welcome to the first video of the new money advent calendar! Whoa, what a big project! I am actually pretty nervous about this. I’m going to try and—no, I am going to do 25 videos in 25 days in the lead up to Christmas. So, uh, I hope…