Chapter - 1, The Earth in the Solar System

SHORT NOTES

THE SOLAR SYSTEM

The Sun, the eight planets, their satellites, asteroids, and meteoroids together make up the Sun's family called the Solar System.

The Sun is the center of the Solar System. It is made up of extremely hot gases.

The Sun is almost 150 Million km away from the Earth

There are 8 planets in the Solar System-

1. Mercury

2. Venus

3. Earth

4. Mars

5. Jupiter

6. Saturn

7. Uranus

8. Neptune

Pluto was the ninth planet but is now considered as a "dwarf planet" since August 2006.

New planet "2003UB313" is a newly discovered dwarf planet. It is larger than Pluto and farthest from the Sun.

EARTH

The Earth is the third planet to the sun and the fifth largest planet.

Earth is the only known planet that supports life.

It's also called as "Blue Planet" since it is covered by oceans.

Earth's shape is 'geoid'.

MOON

It is the only natural satellite of Earth.

Moon's diameter is one-quarter of that of the Earth's.

Moon is about 384,400 km away from the Earth

No life exists on Moon because it doesn't have air and water.

DIFFERENT APPEARANCES OF THE MOON

The Moon appears different on different nights, depending upon its position while revolving around the Earth.

Full Moon (Purnima) appears once every month and New Moon (Amavasya) appears 15 days later.

ASTEROIDS

Asteroids are numerous tiny bodies that move around the Sun between the orbits of Mars and Jupiter.

They move in Asteroid Belts

The largest asteroid in Solar System is "Ceres".

METEORITES

Small pieces of rocks that move around the Sun are called Meteorites.

GALAXY

A Galaxy is a cluster of stars and their systems.

Solar System is present in the Milky Way galaxy which is called Akash Ganga since ancient times in India.

There are millions of galaxies that make the universe.

CELESTIAL BODIES

The Moon, the stars, and other bodies that are visible in the night sky are called Celestial Bodies.

They are not visible during day time because the power of the Sun's light makes them invisible to the naked eyes.

We don't feel the heat and light of other stars because they are far away from us.

CONSTELLATIONS

A group of stars that make a definite pattern in the night sky is called Constellation.

examples- Ursa Major, Ursa Minor, Saptrishi, etc.

POLE STAR

Pole Star is known to retain the same position every night in the sky.

It is also called as "North Star" since it was used to navigate locations in the past. It always points in the North direction.

PLANETS

Celestial Bodies that do not emit light of their own and reflect the light of a nearby star are called Planets.

Most Planets have "satellites" that revolve around them.

ORBIT

The particular and definite elliptical path in which a planet revolves around the Sun is called Orbit,

Orbits are imaginary and fixed.

Satellites revolve around planets in Orbits too.

INNER AND OUTER PLANETS

The Inner Planets are the planets that orbit around the Sun between the Sun and the Asteroid Belt. They are made up of rocks and are close to the Sun.

1. Mercury

2. Venus

3. Earth

4. Mars

The Outer Planets are the planets that orbit around the Sun and are present beyond the Asteroid Belt. They're made up of gases and are away from the Sun.

1. Jupiter

2. Saturn

3. Uranus

4. Neptune

UNIVERSE

The Universe is the largest unit in which we live.

It is a collection of galaxies.

POLES OF THE EARTH

Two places diametrically opposite to each other and which lie on the axis about which a spherical body rotates are called its poles.

Earth has two poles - North and South.

EXERCISE

Q1 ANSWER THE FOLLOWING -

1 HOW DOES A PLANET DIFFER FROM A STAR

Planets do not emit their own light. Example - Earth

Stars emit their own light. Example - Sun.

2. WHAT IS MEANT BY "SOLAR SYSTEM"?

The Sun, the eight planets revolving around the Sun, and other celestial bodies like meteorites and asteroids together make up the Solar System.

3. NAME ALL THE PLANETS ACCORDING TO THEIR DISTANCE FROM THE SUN.

1. Mercury

2. Venus

3. Earth

4. Mars

5. Jupiter

6. Saturn

7. Uranus

8. Neptune

4. WHY IS EARTH CALLED A UNIQUE PLANET?

Conditions on Earth are favorable to support life.

Earth is neither too hot nor too cold. It has air and water which makes survival possible.

5. WHY DO WE SEE ONE SIDE OF THE MOON ALWAYS?

Because Moon completes its revolution around the Earth in 27 days and Moon's rotation on its own axis also takes 27 days. One day of the Moon is equal to 27 days on Earth.

6. WHAT IS UNIVERSE?

Millions of galaxies, huge systems of billions of stars, and dusty gaseous clouds make up the universe. It is the largest unit we live in.

Q2. TICK THE CORRECT -

1 PLANET KNOWN AS "EARTH'S TWIN"

- Jupiter

- Saturn

- Venus

Venus

2. WHICH IS THIRD NEAREST PLANET TO THE SUN?

- VENUS

- EARTH

- MERCURY

Earth

3. ALL PLANETS MOVE AROUND SUN IN A

- CIRCULAR PATH

- RECTANGULAR PATH

- ELONGATED PATH

Elongated Path

4. THE POLAR STAR INDICATES THE DIRECTION TO THE

- SOUTH

- NORTH

- EAST

North

5. ASTEROIDS ARE FOUND BETWEEN THE ORBITS OF

- SATURN AND JUPITER

-MARS AND JUPITER

- EARTH AND MARS

Mars and Jupiter

Q3. FILL IN THE BLANKS -

1 A group of Stars forming various patterns is called a constellation.

2. A huge system of stars is called a galaxy.

3. Moon is the closest celestial body to Earth.

4. Earth is the third nearest planet to the Sun.

5. Planets don't have their own heat and light.