The Solar System
Concept: Stars, Constellations and Other Celestial Bodies
What are stars?
- Stars are luminous astronomical objects that constantly emit heat and light.
- Stars are made with gaseous components.
- We can see many twinkling stars through our naked eyes in the night sky.
- The Sun is the closest star to Earth.
Stars around us:
a) Sun:
- It is a hot ball of glowing gases.
- The Sun is situated at the centre of the solar system.
- The Earth and all other planets belonging to the solar system revolve around the Sun.
- Sun gives us heat and light necessary for the existence of life on Earth.
- In many cultures, the Sun is considered an important deity because of its massive importance.
b) Pole star:
- The Pole star appears like a stationary star in the sky at night.
- This star can be seen in the night sky in the North direction.
- Pole star is called Dhruv Tara in Hindi.
- We cannot see the Pole star from the southern hemisphere.
- In the past, the sailors used to locate the north with the help of the Pole star.
c) Constellations:
- Constellations are a group of stars that can make recognisable patterns in the night sky.
- These groups of stars might take the shapes of animals, objects, or people.
- In many instances, they are named after mythological figures of the ancient world.
- Constellations are used in astronomy, navigation, and storytelling.
- Constellations can be seen through telescopes.
The different constellations are briefly described below—
i) Orion:
- This constellation is clearly visible in the night sky.
- Orion is named after a famous Greek mythological character known by the same name.
- In the middle, it has a set of three stars, and if we join those, they look like a belt; hence is known as Orion’s belt.
ii) Ursa major:
- This constellation has many names like Plough or the Big Dipper, and Great Bear.
- In India, this constellation is called Saptarishi.
- This constellation points towards the North Star.
- In the past, this constellation helped people navigate the northern hemisphere.
- This constellation is made of seven bright stars.
- It looks like a big dipper if we join all the stars with a line.
iii) Pegasus:
- This constellation is named after the Greek mythological character that looks like a winged horse.
- It consists of a square set of four stars and with other stars surrounding that square.
- This constellation is attached to another constellation called Andromeda.
- Except for the square, other parts of this constellation appear fuzzy in the night sky.
iv) Canis major:
- This constellation represents the figure of a dog in the night sky.
- It has Sirius, which is the brightest star in the night sky.
- This constellation is visible in the northern hemisphere during winter and in the southern hemisphere during summer.
Celestial bodies:
The heavenly bodies that are present in the universe are called celestial bodies.
Examples: Stars, planets and satellites.
Different celestial bodies up in the sky:
a) Planets:
- Planets do not emit light and heat like stars. They reflect the light of the Sun.
- These are large celestial bodies moving around the Sun in fixed paths.
Examples: Earth, Jupiter, Venus, Mars, etc.
b) Satellites:
- Satellites are heavenly bodies revolving around the planets.
- They also do not emit light and heat like stars.
- Satellites always revolve in a fixed orbit.
Examples: Moon.
c) Comets:
- Comets are small celestial objects that revolve around the Sun.
- They look like fireballs with long tails in the night sky.
- Comets are only visible when they come close to the Sun.
d) Meteors and meteorites:
- Meteoroids are celestial bodies revolving around the Sun in different orbits.
- If they come out of the orbit, they fall towards the Earth’s surface, catch fire, and are called meteors.
- Meteors may vary in size. If some of their remains reach the surface of the Earth without burning completely, they are considered meteorites.
New Words:
Luminous: Something that possesses the light of its own.
Deity: A god or goddess.
Stationary: Something that does not move.
Atmosphere: A layer of gas mixture surrounding the Earth.
Dipper: A scoop or a ladle.
Did You Know?
- Next to the Sun, Proxima Centauri is the closest star to Earth.
- At present, we know about 88 constellations.
- Asteroids are a type of celestial bodies that are present between the planets Mars and Jupiter.