The Solar System

Throughout the universe there are billions upon billions of galaxies. Within our galaxy, there is a group of planets that go around a star. We call this the solar system. In our solar system there are eight planets and the Sun.

The Sun is the center of our solar system. Everything in the solar system revolves around it. The Sun is a giant ball of gas that gives off light. There are billions of giant balls of gas that also give off light all across the universe. We call these stars, which are the twinkly lights you see at night. The Sun is much brighter than the twinkly stars at night because it is so much closer than the next star. The Sun is 93 million miles away, but the next closest star is in the next galaxy over. That’s so far away that we don’t even measure it in miles, but in lightyears. Because the Sun is so close, we can actually feel it’s heat. I can get so hot sometimes that you can fry an egg just from the heat of the Sun.
The first planet in our solar system, which is closest to the Sun, is Mercury. Mercury is the smallest planet in our solar system. Because it’s so close to the Sun it also gets super-hot. We also count time weirdly on Mercury. A year on Mercury is only 88 days, unlike Earth where it is 365 days. Mercury doesn’t have any atmosphere, so it doesn’t have any weather. There is no rain or snow or wind on Mercury. This might be why there are so many craters on Mercury. Normally rocks that fall towards a planet would get burnt up in the atmosphere, but Mercury doesn’t have an atmosphere so rocks crash land on the surface, creating these giant craters.

The next planet in our Solar system is Venus. Venus is slightly larger than Mercury and smaller than Earth. Although Venus isn’t as close as Mercury to the Sun, Venus is hotter than Mercury. Venus is the hottest planet in our solar system. This is because Venus has a thick atmosphere which keeps all the heat from the Sun in. The atmosphere is so thick that walking through it would be like walking through honey. Venus is also the closest planet to Earth. This is why some people can see Venus in the night sky. It’s also very easy to see Venus at night sometimes because Venus is very bright. Venus is not a star, so it doesn’t make its own light, but its thick atmosphere reflects a lot of sunlight, making it look like it’s shining.
The Third planet in our solar system is Earth. As far we know, all life lives on Earth. We haven’t discovered any animals or plants or even aliens on other planets, so we think Earth is only home life has. It took a long time for life to find a home on Earth. Originally Earth was an extremely hot planet with no atmosphere like Mercury is today. Life couldn’t live on a planet like that. Over millions of years, Earth cooled down to temperatures we are used to, and the oceans began to form, and oxygen was made. All of these are important for life to live, and there aren’t a lot of planets that have all of these in the right amount. Earth does, and about 3 billion years ago, the first life on Earth appeared, and over time evolved into all the life we see today. As we explore our solar system and other galaxies, maybe we will find life somewhere else.
Mars is the fourth planet in our solar system. We sometimes call Mars the red planet because it looks red when we look at it through our telescopes. Mars looks red because its surface is full of iron which has a red look. There are no seas on Mars but there is ice on its north and south poles. It’s really cold there. Mars is the most explored planet in the solar system after Earth. We sent robots called rovers there to drive and look around Mars. These rovers are looking for water underground and to see if there are any signs of life there. In the future we might be able to go to Mars. It takes six months to go from Earth to Mars. Once there, we will have to live in giant domes because there is no oxygen on the surface. The gravity on Mars is much less than on Earth, so if you ever live on Mars, you would be able to jump much higher than you can on Earth.

The fifth planet in our solar system is Jupiter. Jupiter is the biggest planet in our solar system. You could fit 1300 Earths into Jupiter. It’s that big. Jupiter is called a gas giant because most of the planet is made out of gas. You have to go really deep into Jupiter to find its core. A core of a planet is its center which is usually made out of metal. Jupiter’s core is as big as Earth, and all around it is the giant ball of gas. These gases sometimes become clouds and have interesting shapes. All across Jupiter, there are giant strips which are made out of these gas clouds. There is also a giant spot on Jupiter’s surface. This spot is called the Great Red Spot and is a giant storm that has been going on for hundreds of years. Jupiter has rings around it, but they are not as big or as pretty as the rings of other planets in the solar system.
Saturn is the sixth planet in our solar system and is very similar to Jupiter. It’s one of the bigger planets in the solar system. You could fit about 700 Earths into Saturn. Saturn is also a gas giant with a small rocky core. Saturn is smaller than Jupiter, but it has bigger and prettier rings around it than Jupiter does. Saturn’s rings are made out of millions of pieces of rock and ice. The smallest pieces are as small as a golf ball, and the largest one’s are a half a mile wide. Saturn also has 18 moons. Saturn’s biggest moon is called Titan. Titan is the second largest moon in the solar system. What makes Titan really cool is that it’s covered in ice and oil and has ice volcanoes which shoot out water and ice instead of lava.

The next planet in our solar system is Uranus. When you look at Uranus through a telescope you see a blueish-green planet. Uranus is covered in a stinky gas which makes its atmosphere this color. Uranus also has rings around it, but they aren’t as pretty as Saturn’s. Uranus is also an ice giant. Because Uranus is so far away from the Sun almost all the water on the surface of Uranus turned into ice. As you get closer to the core of Uranus the ice gets hotter and becomes water, and sometimes it becomes so hot that it becomes a special superheated liquid which would normally turn into gas. Unlike what we have on Earth, Uranus’ poles are warmer than the rest of the planet. This is because Uranus is tilted on its side, so more sunlight goes there. Summer at the south pole on Uranus lasts 42 years.

Neptune is the eighth planet in our solar system. Neptune is so far away that we can’t ever see it in the night sky without a telescope. Like Uranus, Neptune is an ice giant, but it also has a lot of water on its surface. Neptune also gets very windy and has a lot of storms on its surface. These storms change how Neptune looks when you look through a telescope. Neptune also has rings around it, but since they are so small, they are very hard to see unless you have a special telescope. Neptune has seven moons. Neptune’s largest is called Triton. Triton is one of the coldest places ever recorded. The temperature there is just 98° F away from the lowest possible temperature in the entire Universe.

Up until a couple of years ago there used to be a ninth planet in our solar system. This planet used to be called Pluto. Pluto didn’t disappear. It’s still out there, but we no longer call it a planet. This is because we decided that planets need to be a certain size and Pluto is too small. Pluto is a lot smaller than a lot of things in our solar system, like some asteroids, which are giant rocks that float around in space. We didn’t want to have all the asteroids be planets. We would have way too many planets in the solar system if we did, so we decided that Pluto isn’t a planet anymore. One of the interesting things about Pluto is that sometimes it gets closer to the Sun than Neptune does, so scientists have a hard time saying that Pluto is the furthest thing in our Solar system.