CBSE Class 3 Science – 13. the Sun, Moon and Stars (Notes)

                                                             Planets of Solar system

Mercury         Venus           Earth            Mars           Jupiter         Saturn       Uranus      Neptune

 

Solar system – The family of the sun, planets and their satellites together is known as the solar system.

There are 8 planets in the solar system.

 It consists of Sun and all other object that travels around Sun.

 These objects include planets, asteroid, natural satellites, meteoroids etc.

 Our solar system is a part of the Milky Way galaxy.

 

Orbit – A path on which planets revolve around the sun is called orbit.

 

 Sun – The star at the centre of the solar system is called sun.

 The sun is the closest star to us.

 It is a ball of fire and gives us heat and light.

 Sun diameter is about 110 times wider than earth.

 Around 74% of the sun mass is made up of hydrogen.

 The earth can fit inside the sun 1.3 million times.

 

Planet – A very large round object in space that moves around the Sun or another star is called    planet.

Planets do not have light of their own.

It reflects the sunlight that falls on them.

There are 8 planets in the solar system.

 Mercury is the closest planet to the sun.

 Earth is the third planet and is the only planet which has life on it.

 Mercury is the smallest planet.

 Mars is known as the red planet.

 Venus is called the evening star.

 Saturn has rings around it.

 Uranus and Neptune are very far away.

 

Movements of the earth –

Rotation

Revolution

 

Rotation– The movement of the Earth on its axis is called rotation.

Revolution – Movement of earth around the sun in a fixed path is called revolution.

Satellite – An object that moves around a planet are called satellite.

Moon – Satellites that shines by the sun reflected light and revolves around the earth is called moon.

 It revolves around the earth from west to east in about 29.5 days.

 In 1969, Neil Armstrong was the first human to set foot on the moon.

 The closest heavenly body to the earth is the moon.

 It is the Earth natural satellite.

 Moon has no light of its own.

 It rotates and revolves around the earth.

 The moon has no atmosphere.

 The moon completes one rotation on its axis in 27 days.

 It takes 27.32 days to complete one revolution around the earth.

 

Moonlight – Light that comes from the moon is called the moon light.

Craters – Holes on the surface of the Moon caused by the impact of meteoroids are called craters.

Phases of the Moon – The different ways the moon looks from earth over about a month is called the phases of moon.

The moon appears to change its shape every night.

New Moon – The moon when it appears as a thin curved line is called New Moon.

Crescent moon – The moon as it appears in its first or last quarter is called crescent moon.

Gibbous moon – The phase of the moon in which its part is greater than a semicircle and less than a circle is called in gibbous Moon.

Full moon – The moon when it appears as a complete circle is called full moon.

 

                                                          Phases of the moon  

New moon	Crescent moon	Half moon	Gibbous moon	Full moon
It appears as a thin curved line	As it appears in its first or last quarter	As it appears as a half part	Its part is greater than a semicircle and less than a circle	Appears as a complete circle

 

Star – A very large ball of bright glowing hot matter in space is called star.

 Stars are big balls of Fire.

 It produces heat and light.

 The sun is also a star.

 Sun is the closest star from the Earth.

 Stars can be seen with the naked eyes too.

 

Galaxy – A group of many stars, with gas, dust and dark matter are called galaxy.

Milky Way galaxy – The Galaxy of which the sun and the solar system are a part is called Milky Way galaxy.

Telescope – Instrument used to see far away object closely and clearly it called telescope.

Constellation – A group of stars in the sky appear to form a shape or pattern is called constellation.

 There are about 88 constellations in the sky.

 Example – Ursa Major, Orion etc.