Understanding basics of our Solar System
Our Solar System is a family of Sun – having the Sun at the center, eight planets revolving around the Sun, with the Satellites and other “celestial bodies” termed as Asteroids and Meteoroids.
“Sol” in roman mythology refers to the “Sun God”. Hence, “solar” means “related to the sun”.
What are Celestial Bodies, Stars and Planets?
- Celestial Bodies
- The sun, the moon and all other objects shining in the sky are called celestial bodies
- Some of these are very big and hot, and emit their own heat and light. These are made of gases and are called as “Stars”, for eg. Sun.
- Celestial bodies having their own heat and light
- There are countless twinkling stars in the sky which are similar to the Sun, but they are far away hence we do not feel their heat
- The Sun
- Is made of extremely hot gases
- It is 150 million km away from earth
- It takes 8 minutes for the light to reach from the Sun to the Earth
- Celestial bodies having no heat and light of their own
- They shine when light from a star falls on them
- The word “planet” comes from the Greek word “Planetai” which means “wanderers”
- Like our “earth”, there are seven other planets that get heat and light from the Sun
- The Earth
- Its 5th largest planet by size
- Its slightly flattened at the poles, hence its shape is often termed as “Geoid”
- Earth’s Twin – Venus is called as Earth’s Twin because of having similar shape and size as Earth
- Often called a “Blue Planet” because it appears blue from the outer space owing to two third’s space being covered by water
- Why we only have 8 planets now? (earlier there were 9 planets)
- “Pluto” was considered as the 9th planet until August 2006
- In a meeting of the International Astronomical Union, it was termed as “dwarf planet” (like other celestial objects Ceres, 2003 UB313)
- Numerous tiny bodies which revolve around the sun
- They are usually found between Mars and Jupiter – called as the Asteroid Belt
- They are believed to be parts of some planet which exploded in the past
- The small pieces of rocks which move around the sun
- Sometimes they come near earth and tend to drop upon it, in the process sometimes they get completely burnt due to friction thus causing a flash of light. In some cases, if not completely burnt, they fall to the earth’s surface causing a hollow.
- A huge system of billions of stars, clouds of gases and dust
- The Milky Way – Akash Ganga
- Our solar system is a part of the milky way galaxy
- There are many such galaxies in the Universe
What is a constellation?
- Groups of stars form various patters sometimes, these patterns are termed as constellations
- For eg. Ursa Major or Big Bear
- One of the most easily recognizable constellations is “Saptarishi” – a group of 7 stars. It is also a part of Ursa Major.
- Saptarishi helps us find the location of the Pole Star or North Star (star which indicates the north direction)
- It lies in the straight line from the last star in the Saptarishi
- Do not have their own light
- They revolve around a planet
- Our Natural Satellite – The Moon
- We see a full moon once in a month – its called Poornima – Full Moon Night
- Once in a month, we see a clear sky without the moon – its called Amavasya – New Moon Night
- During the day time, we don’t see the moon because of the bright sunlight
- It is 3,84,000 km away from earth
- It takes 27 days for the moon to complete one revolution of the earth. The interesting part is, it takes exactly the same time to spin around its own axis. Hence, only one side of the moon is visible to us on the earth.
- First Man to step on the surface of the Moon – Neil Armstrong – 21 July, 1969
- Human-made Satellite
- It is artificial body created by scientists
- It is launched with the help of a rocket and is placed in the orbit of a planet
- Usually used for communication, information gathering about the universe, etc.
- Some Indian Satellites – EDUSAT, INSAT, IRS etc.