The solar system
The solar system is our local area of space. It contains the sun, eight planets, more than 100 moons , as well as countless comets and asteroids. As its center is the sun, our nearest star. The sun’s gravity keeps everything else trapped in it’s orbit.
Distance from sun
The red line to the right shows the distance of each planet from sun in millions of kilometers. Mercury is the closest and Neptune is the further away. Earth is about 150 millions kilometers from sun.
The four planets are nearest to the sun are called “inner planets”. They are also known as rocky planets because they are balls of rock and metal. They are dense and have central cores made of iron.
The four planets furthest away from sun are known as “outer planets”. They are huge balls of gas (mainly hydrogen and helium) and liquid and are known as gas giants. Uranus and Neptune are also known as the ice giants.
In any year there can be up-to seven solar or lunar eclipses , when light from the sun or moon is blocked for the short time. Solar eclipses are more common, but are seen only in narrow area. Lunar eclipses can be seen anywhere on the earth where the moon is shining in the sky.
The lunar eclipse
A Lunar eclipse happens when the earth passes between the sun and the moon , so that the earth casts a shadow on the moon.
The solar eclipse
A solar eclipse happens when the moon passes between the earth and sun , casting a shadow on the earth. A total eclipse lasts for up-to eight minutes.
BELT between Mars and Jupiter is the asteroid belt. It separate the inner planets from the outer planets. About 15000 asteroids have been found and named. They are thought to be rocks that never clumped together to form planet.
- Only six planets were known before telescopes were first used to look at the sky in 1609.
- The planets were born in a huge clouds of gas and dust about 4.5 billion years ago.
- About four billions years ago the sun was 25% dimmer than it is today.
- Halley’s comet doesn’t orbit the sun in normal clock wise direction. It travels beyond Neptune to inside the orbit of Venus.
- Excluding the sun, Jupiter and Saturn contains 90% of solar system’s mass.