Cosmology: Science dealing with the nature and origin of the universe.
Big Bang Theory: Canon Lemaitre
Steady State Theory: Hermann Bond and Thomas Gold.
Pulsating universe theory: Allan Sandage.
One Parsec = 3.26 light years.
Hydra is the largest constellation.
When brightness of a star increases 20 magnitudes or more, it is called a supernova.
Sun accounts for 99.85% of the mass of the solar system.
Suns Revolutionary period= 250 m years
Rotation time = 25 days
Planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
Venus and Uranus rotate anti- clockwise at their axis, whereas all other planets rotate clockwise.
Largest Terrestrial Planet:- Earth
Smallest Jovian Planet:- Neptune
Mercury and Venus have no satellites.
Jupiter has the largest rotational velocity.
Genemede of Jupiter :- Largest Satellite
Titan is the only satellite in the solar system with an atmosphere of its own.
Saturn has the least density among all the planets.
Uranus is also known as Green planet.
Greatest satellite of Neptune : Triton
Movement of the Earth.
1) Rotation: West to east in 24 hours (produces day and night) – Line separating light and dark halves is known as the circle of illumination.
2) Revolution: Movement around the sun 365 ¼ days (produces seasons) – Jan 2 : Closest to the sun- called Perihelion. July 4 : Farthest from the sun- called Apehelion.
3) Eccentricity: (Produces Ice-age and Global Warming) Shape of the earth’s orbit changes in a cyclic period running between 90,000- 1,00,000 years.
4) Precession: This is the conical motion of the axis of the spinning earth, like a spinning top. Takes about 26,000 years to complete one cycle.
Presently – pointing at Pole star.
AD 4000- pointing at Alpha cephai
A D 14,000 – pointing at Star vega
Summer Solistice: 21st June: Sun overhead at tropic of cancer.
Winter Solistice: 22nd Dec : Sun overhead at the tropic of Capricorn.
Vernal Equinox: 21st March.
Autumn Equiox: 23rd Sep
Our moon is 1/4th of the size of Earth.
Blue Moon is said to occur when the second full moon appears within the same month.
Highest Mountain on Moon: Liebnitz: 10,660m
Neil Armstrong and Edwin Aldrin: Set foot on the ocean of Tranquility
In a calendar year, a maximum of seven eclipses can occur( combining solar and lunar eclipses)
Remember 1 degree latitude or longitude represents 111 Km ( along equtor)
Longitude and Time
Rem: E-G-A [ East- gain- add]
W-L-S[ West- lose- subtract]
Earth moves 1 degree in 4 minutes.
Standard meridians differ from Greenwich Meridian by the multiples of 15degree or 7.5degree.
USA and Canada have 5 time zones.
India has one time zone.
-82.5 degree east from the Standard time
- 5 hours and 30 minutes ahead of GMT
The International Date Line:
- 180 degree Meridian is the international date line.
- A traveler crossing this date line from east to west will lose a day.
- A traveler going from west to east will gain a day.