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Middle school Earth and space science - NGSS
Unit 1: Lesson 3
The solar systemThe solar system
Our solar system formed from a nebula about 4.6 billion years ago. It consists of the sun, four inner planets (Mercury, Venus, Earth, and Mars), the asteroid belt, four outer planets (Jupiter, Saturn, Uranus, and Neptune), and the Oort cloud. Created by Khan Academy.
Want to join the conversation?
- Where's Pluto, And the other dwarf planets?
They are definitely not asteroids, as they are too massive, and Pluto at least, has moons(3 votes)- Pluto orbits the Sun about 3.6 billion miles (5.8 billion km) away on average, about 40 times as far as Earth, in a region called the Kuiper Belt.(3 votes)
- What is the actual distance from the Sun to the Earth? And do we know how many asteroids are in the Asteroid Belt?(1 vote)
- Earth's average distance to the Sun is about 93 million miles (150 million kilometers). We do not know exactly how may asteroids are in the asteroid belt, it is estimated to contain between 1.1 and 1.9 million asteroids larger than 0.6 miles (1 kilometer) in diameter, and millions of smaller ones.
I hope this helps! Let me know if you have any other questions :)(6 votes)
- when was the last time Halley's comet was visible from earth?(2 votes)
- The last time people on earth could see it was in 1986.(2 votes)
- Why does saturn have the ring around it?(2 votes)
- Saturn has a big gravitational pull, so it pulled some pieces of comets, asteroids, or shattered moons that broke apart before it reached the planet. They also include lots small chunks of ice.(2 votes)
- how do you measure the distance between Earth and the Sun(2 votes)
- The distance from Earth to Sun = 1 AU. AU standing for astronomical unit.(2 votes)
- thats so cool i never knew(2 votes)
- what causes stars?(1 vote)
- many different gases bundle up and explode later creating a star. This process takes quite a while.(2 votes)
- was the sun made of supernova?(1 vote)
- Yes. An earlier star went supernova, which created an interstellar cloud. Then, under gravity, the interstellar cloud consolidated to form the Sun and solar system.(2 votes)
- Thats so cool. I also want to know what the distance from earth to the sun is?(1 vote)
- The distance from Earth to the Sun, sometimes referred to as one astronomical unit, is about 93 million miles or 150 million kilometers.(2 votes)
- how did they find the solar system(1 vote)
Video transcript
- [Narrator] The Earth isn't
flat, but the solar system is. About 4.6 billion years ago, 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 the 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 as gravity keeps an 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. And 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 Halley'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 wanna 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 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 and 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 is. 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. 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 degree Celsius. It's also the windiest
planet in our solar system with winds going at more than
2000 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. And 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 could help solve some of the solar system's great mysteries too.