class 8 ch 1 of solar system and galaxypptx

solar system and its components

1. The Solar System Class 8 th

2. Sun- A Star Sun- a medium sized star Diameter is more than one hundred times that of the earth Is has eight planets going round it and all together they form Solar System

3. The Sun contains about 99 % of all the material found in our solar system The heat of the Sun comes from a kind of nuclear explosion where the temperature is about 16,000,000 degree centigrade This heat is the source of all life on Earth

4. Orbital Movement The eight planets move round the Sun in orbits which are not circular but elliptical or oval in shape The time for each planet to make one journey round the Sun determines the length of that planet’s year As the Earth’s revolution is not exactly 24 hours, the year gets a little out of step with clocks and calendars. To correct this, every fourth year is a leap year which has an extra day (366 instead of 365). Mercury whizzes round in 88 days Neptune takes 165 earthly years

5. Diameters of different planets The planets differ in size: Diameter of Mercury: 4878 km Diameter of Jupiter : 143,884 km Diameter of Earth : 12,756 km

6. Temperature of different planets Mercury and Venus are too close to the Sun and so hot that no life could exist there. The surface temperature of Venus is 462 degree centigrade and the clouds of sulphuric acid The side of the Mercury facing the Sun have the temperature430 degree centigrade and -180 degree centigrade Temperature of Saturn is - 172 degree centigrade & Jupiter - 150 degree centigrade The force of GRAVITY on Jupiter is 2.4 times as much on Earth

7. Question from Exercise Q1. What causes the extreme temperatures on the different planets of the Solar System? Ans. Extreme temperatures on different planets in the solar system are caused by i. distance from the Sun, Ii. in some cases by speed of rotation of the planet. If one side is in the shadow (turned away from Sun), Iii.the temperatures will decrease to a point where gases (nitrogen) become liquid.

8. Q2. How have the Hubble and Chandra Telescopes helped scientists? Ans. The Hubble telescope is a space-based observatory launched in 1990. It has helped scientists to look further into space because, being in space and clear of the Earth’s atmosphere, the Hubble can see more distant objects and also much more detail of the more familiar ones such as our planet. The information is sent back to Earth electronically Chandra is designed to observe X-rays from high-energy regions of the universe. Chandra is still a new telescope, but it has already made some amazing discoveries. It has found black holes all across the universe and also found proof for the first time of two super-massive black holes. It has also given clues about how the universe has evolved over time and even about the planets in our own neighborhood.

9. Mars There may be some kind of life on Mars, single celled creature Several spacecraft have been there to scope up soil from the surface & analyze it, sending back radio massages Source of life is --------- oxygen & water There is small amounts of oxygen in Mars’ atmosphere Some water in the form of ice under the surface Temperatures are very harsh(-140*C to + 17*C) Some form of life might have been possible

10. Saturn Interesting Planet 2 nd largest planet Diameter: 120,000 (nine & a half times the size of the earth) Made up of largely gas & iron or rock core Bitterly cold with surface temperature of -180*C Spins on its axis in 10 hours 39 minutes Revolves around the Sun: 29.5 Earth Years Saturn have seven gigantic rings 300.000 km across, 3000 meter thick Rings are made of ice and particles

11. Natural satellite T he solar system, except for Mercury and Venus, other planets have satellites i.e . moons. How many moons does each planet have? Earth—one moon; Mars—two moons; Jupiter—63 moons; Saturn—60 moons; Uranus—27 moons, Neptune—13 moons .

12. Questions from Text Elaborate sun is the source of life. The Sun contains about 99 % of all the material found in our solar system The heat of the Sun comes from a kind of nuclear explosion where the temperature is about 16,000,000 degree centigrade This heat is the source of all life on Earth

13. Is life exist on Mars? There may be some kind of life on Mars, single celled creature Several spacecraft have been there to scope up soil from the surface & analyze it, sending back radio massages Source of life is --------- oxygen & water There is small amounts of oxygen in Mars’ atmosphere Some water in the form of ice under the surface

14. Why Saturn is an interesting planet of solar system? Made up of largely gas & iron or rock core Bitterly cold with surface temperature of -180*C Spins on its axis in 10 hours 39 minutes Revolves around the Sun: 29.5 Earth Years Saturn have seven gigantic rings 300.000 km across, 3000 meter thick Rings are made of ice and particles

15. Homework Collect some interesting facts about universe. 10 marks assignment Submission date is 26-08-21 a [email protected]

16. Interesting planet Diameter Made up of: Temperature Spinning on axis Saturn’s Rotation Rings of Saturn Moons of Saturn