Outer space
This post will teach you about outer space. From black holes to moons, and a quiz to end, this post is going to be a very exciting one!
Black holes
Black holes are left behind when a supergiant star dies, in an explosion called a supernova. The central point of the black hole is called 'singularity'. At a certain distance from this point, the gravitational pull is so strong that not even light can escape it.
Galaxies
What are galaxies? Galaxies consist of dust, gas and millions of stars that are held together by their own gravity. There are 3 types of galaxies: spiral, elliptical, and irregular. A spiral galaxy is shaped like a disk and has long spiralling arms in which new stars are born. An elliptical galaxy is ball-shaped and consists of older stars. Galaxies that have no fixed shape are called irregular galaxies. The galaxy we live in is called the Milky Way. It is a spiral galaxy that consists of over 200 billion stars as well as the Solar System. The Solar System is located on one of the Milky Way's arms, the Orion Arm.
The Solar System
The Sun, the eight planets and their moons, dwarf planets (Pluto), asteroids, comets and meteoroids are together known as the Solar System. The planets closest to the Sun are called the inner planets. These planets are largely made up of rocks and include Mercury, Venus, Earth, and Mars. Jupiter, Saturn, Uranus and Neptune are called the outer planets. The outer planets consist of gas, which is why they are also known as 'gas giants'.
Comets and asteroids
Thousands of asteroids are found in a region between Mars and Jupiter. This region is known as the Asteroid Belt. Some asteroids can have a diameter of about 1,000 kilometres. When a comet passes close to the Sun, the outer layers of its icy core melt and release jets of gas and dust particles. These are pushed behind the comet to form the tail. Some comets have tails that are as long as 150 million kilometres!
Moons
Just as the planets circle the Sun, moons circle most of the planets in the Solar System. As everyone knows, the Earth has only one moon. But some planets (Jupiter, for example) are known to have as many as 60 moons. Their is no air or water on the Moon, which makes it impossible to support life. The Moon does not always appear full and round. Its shape goes through various 'phases'. In the 'new moon' phase the Moon is between the Earth and the Sun. The side facing the Earth is away from the Sun and, hence, dark. This makes the Moon invisible from Earth. After a couple of days, a thin line lit by the sun is seen. This is the crescent Moon. When the Moon is halfway around the Earth, the full sunlit side is visible. This is the 'full moon' phase.
Quiz
1. What does a galaxy consist of?
2. How are black holes formed?
3. Can light escape a black hole?
4. What type of galaxy is the Milky Way?
5. What is the name of the third outer planet?
6. What is a comet made of?
7. Where is the Moon during the 'full moon' phase?
8. What is the name of the second inner planet?
Answers
1. Dust, gas and millions of stars
2. They are left behind in a supernova
3. No
4. A spiral galaxy
5. Uranus
6. Ice
7. Halfway around the Earth
8. Venus
Black holes
Black holes are left behind when a supergiant star dies, in an explosion called a supernova. The central point of the black hole is called 'singularity'. At a certain distance from this point, the gravitational pull is so strong that not even light can escape it.
Galaxies
What are galaxies? Galaxies consist of dust, gas and millions of stars that are held together by their own gravity. There are 3 types of galaxies: spiral, elliptical, and irregular. A spiral galaxy is shaped like a disk and has long spiralling arms in which new stars are born. An elliptical galaxy is ball-shaped and consists of older stars. Galaxies that have no fixed shape are called irregular galaxies. The galaxy we live in is called the Milky Way. It is a spiral galaxy that consists of over 200 billion stars as well as the Solar System. The Solar System is located on one of the Milky Way's arms, the Orion Arm.
The Solar System
The Sun, the eight planets and their moons, dwarf planets (Pluto), asteroids, comets and meteoroids are together known as the Solar System. The planets closest to the Sun are called the inner planets. These planets are largely made up of rocks and include Mercury, Venus, Earth, and Mars. Jupiter, Saturn, Uranus and Neptune are called the outer planets. The outer planets consist of gas, which is why they are also known as 'gas giants'.
Comets and asteroids
Thousands of asteroids are found in a region between Mars and Jupiter. This region is known as the Asteroid Belt. Some asteroids can have a diameter of about 1,000 kilometres. When a comet passes close to the Sun, the outer layers of its icy core melt and release jets of gas and dust particles. These are pushed behind the comet to form the tail. Some comets have tails that are as long as 150 million kilometres!
Moons
Just as the planets circle the Sun, moons circle most of the planets in the Solar System. As everyone knows, the Earth has only one moon. But some planets (Jupiter, for example) are known to have as many as 60 moons. Their is no air or water on the Moon, which makes it impossible to support life. The Moon does not always appear full and round. Its shape goes through various 'phases'. In the 'new moon' phase the Moon is between the Earth and the Sun. The side facing the Earth is away from the Sun and, hence, dark. This makes the Moon invisible from Earth. After a couple of days, a thin line lit by the sun is seen. This is the crescent Moon. When the Moon is halfway around the Earth, the full sunlit side is visible. This is the 'full moon' phase.
Quiz
1. What does a galaxy consist of?
2. How are black holes formed?
3. Can light escape a black hole?
4. What type of galaxy is the Milky Way?
5. What is the name of the third outer planet?
6. What is a comet made of?
7. Where is the Moon during the 'full moon' phase?
8. What is the name of the second inner planet?
Answers
1. Dust, gas and millions of stars
2. They are left behind in a supernova
3. No
4. A spiral galaxy
5. Uranus
6. Ice
7. Halfway around the Earth
8. Venus
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