World Geography
GEOGRAPHY
UNIVERSE
• Study of the universe is COSMOLOGY
• The solar system consists of SUN +8 planets+1 dwarf
planet+natural satellite
• ANDROMEDA is our nearest galaxy
• MILKY WAY OR AKASH GANGA is our own galaxy.
• Sun has its own light which is also the nearest star.
• The big bang occurred 13.8 billion years ago
which has lead to the formation of galaxy.
• Stars explosion leads to make neutron star which
collapses and compacts to become BLACKHOLE.
SUN---
• 99% of the solar system is sun in terms of mass.
• The nearest star to earth.
• Shining surface- Photosphere
• The major source of energy.
• Distance from earth-14958900 km
• Surface temperature – 5778K or 5504.85 degree celsius
• Temperature at centre 15000000 degree Celsius
• consists of Hydrogen and helium gas
• 224 million years to complete one revolution and is called
COSMIC YEAR.
• Sun LIGHT takes 8 mins 17 sec to reach theearth
• Energy is produced by nuclear fusion.
PLANETS--
• MERCURY---smallest and innermost
planet/fastest revolution, NO atmosphere, no
satellite
• VENUS----morning and evening star/brightest
star/hottest planet/earth’s twin,
• EARTH---blue planet
• MARS—red planet, , highest mountain- Nix
Olympia, 2 satellites( phobos,deimos)
• NEPTUNE---greenish star/coldest planet/farthest planet
from sun/slowest revolution, green due toMETHANE
• JUPITER—biggest planet
• URANUS—green planet
• URANUS AND VENUS move east to west—
retrograde motion,rest all rotate west to east.
• SATURN- Named on roman god,second largest,maximum
number of satellites
MOON---
• Study of the moon is selenology.
• Distance from earth-382200 km
• The only natural satellite of earth
• 1/4th of the earth in terms ofsize
• Si, Fe,mg are found.
• Also known as fossil planet.
• Max distance from earth-apogee
• Min distance from earth - perigee
• Light takes around 1 sec to reach us from
themoon. OTHER COMPONENT OF SOLAR
SYSTEM---
• Asteroids—the belt of minor planet revolving around sun
between Mars and Jupiter.
• Meteoroid –small rock/particle of debris in oursolar
system.
• Meteor –meteoroid burn up and passes through
earth’s atmosphere
• Fireball—bright meteor.
• Comet—small celestial body consist of ice,rock anddust.
• Haley’s comet—famous comet
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