Our Sun is actually a star. Like all stars, it is an incredibly hot ball of gas. It is so big that more than a million Earths could fit inside it. Now our Earth doesn’t seem so big, does it? The Sun and the planets, together with millions of chunks of ice called comets and thousands of lumps of rock called asteroids, make up our Solar System.
The solar system has eight planets, and an asteroid belt. Comets also orbit the Sun. The planets are: 1. Mercury, 2. Venus, 3.Earth, 4.Mars, 5.Jupiter, 6.Saturn, 7. Uranus and 8.Neptune.
A Galaxy Of Stars
The stars we can see from Earth look small and faint because they are amazingly far away. They lie outside our Solar System and may be bigger or smaller, hotter or cooler, older or younger than our Sun. Many may have their own solar system, too. All the stars we can see in the night sky belong to a vast galaxy called the Milky Way. This is a spiral galaxy that is shaped like a fried egg, thick at the centre and thinner on the outside.
The stars we can see from Earth look small and faint because they are amazingly far away. They lie outside our Solar System and may be bigger or smaller, hotter or cooler, older or younger than our Sun. Many may have their own solar system, too. All the stars we can see in the night sky belong to a vast galaxy called the Milky Way. This is a spiral galaxy that is shaped like a fried egg, thick at the centre and thinner on the outside.
A colossal cosmos
The Milky Way is unimaginably big, but it is only a very tiny part of the Universe. There are billions more galaxies in the Universe, some shaped like spirals, others like gigantic footballs.
The Milky Way is unimaginably big, but it is only a very tiny part of the Universe. There are billions more galaxies in the Universe, some shaped like spirals, others like gigantic footballs.
Universal Forces
A few basic forces are in control of the universe. A force called gravity pulls little objects towards bigger objects. For example, when a ripe falls off a tree on Earth, gravity pulls it towards the Earth’s surface and makes it hit the ground.
A few basic forces are in control of the universe. A force called gravity pulls little objects towards bigger objects. For example, when a ripe falls off a tree on Earth, gravity pulls it towards the Earth’s surface and makes it hit the ground.
Let’s play ball with gravity
When you are next playing ball on a warm, sunny day, remember that you owe your fun to the laws of the Universe. Invisible powers are at work! You cannot see gravity, but it is the force that makes your ball curve through the air and fall back to the ground at a certain speed. Earth’s gravity also acts on the Moon, making it circle around the Earth each month. Gravity also makes the Earth orbit the Sun in a near-circle. It makes one complete lap in a year. Planet Mars is smaller than the Earth and has just one-third of its gravity. There, because the force of gravity is weaker than on Earth, a ball will fly three times further when it is hit with the same force. Sports rules will need to be different when people play ball on Mars!
Tiny particles called atoms are the smallest pieces of matter. Forces inside atoms hold them together. These forces can stick some atoms of the same type together or stick atoms of different types together to form molecules.
Atoms make up everything in the Universe. They are like tiny building blocks. Radiation
All objects in the Universe give out radiation, which is any form of energy. Light is type of radiation that we can see, and heat is form of radiation that we can feel. Other types of radiation need special equipment to be detected, the sun gives off lots of light and heat, as well as other types of radiation.
When you are next playing ball on a warm, sunny day, remember that you owe your fun to the laws of the Universe. Invisible powers are at work! You cannot see gravity, but it is the force that makes your ball curve through the air and fall back to the ground at a certain speed. Earth’s gravity also acts on the Moon, making it circle around the Earth each month. Gravity also makes the Earth orbit the Sun in a near-circle. It makes one complete lap in a year. Planet Mars is smaller than the Earth and has just one-third of its gravity. There, because the force of gravity is weaker than on Earth, a ball will fly three times further when it is hit with the same force. Sports rules will need to be different when people play ball on Mars!
Tiny particles called atoms are the smallest pieces of matter. Forces inside atoms hold them together. These forces can stick some atoms of the same type together or stick atoms of different types together to form molecules.
Atoms make up everything in the Universe. They are like tiny building blocks. Radiation
All objects in the Universe give out radiation, which is any form of energy. Light is type of radiation that we can see, and heat is form of radiation that we can feel. Other types of radiation need special equipment to be detected, the sun gives off lots of light and heat, as well as other types of radiation.
These four pictures of the Sun show different radiation temperature in the Sun’s atmosphere. They were taken by an observatory in space called SOHO, which studies the Sun.