SOLAR
SYSTEM
STARS
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HOLES
METEORS
AND METEORITES
ASTEROIDS
COMETS
GALAXIES
NEBULAE
GLOSSARY
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Earth
: The Living Planet
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Name of
the Planet |
Earth |
Position
in Solar System |
The Earth
is the third planet from the Sun and the only planet in the
Solar System known to support life. |
Constituents |
rocky,
ferrous |
Atmosphere |
nitrogen,
oxygen |
Average
Distance from Sun |
150,000,000
km/93,000,000 mi |
Orbit
Time |
1 Earth
year |
Diameter |
12,760
km/7,920 mi |
Average
Density (water=1) |
5.5 |
Satellites |
Moon |
Average
Surface Temp |
15 ºC
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Rotational
Period |
1 day |
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Description:
The third planet from the
Sun is our planet
Earth. It is the only known object in the universe as far as we
know which harbors life. All the other cases where life is supposedly
present on another planet are at best good hypothesis or at most
figments of imagination.
The diameter of the Earth
is 12756 km. It rotates on its axis once in 23 hours 56 minutes
4.1 seconds, with a period of revolution around the Sun of 365.256
days i.e. Earth moves around the Sun at the speed of 29.79 km per
second.
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Source:Unknown
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![](images/Planets/Earth/Apollo8.jpg)
Earth Rise: Phases of the Earth as seen from
the Moon
Source: NASA/NSSDC
NASA Photo ID: AS08-14-2383 File Name: 10074963.jpg
Film Type: 70mm cn Date Taken: 12/22/68
Title: View of rising Earth about five degrees above the Lunar horizon.
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There are several
dozens of speculations about the formation of the Earth. According
to the generally accepted theory, several billions of years ago, the
Earth was formed from primitive material called 'Conchites' which
were meteoritic in nature. In the beginning, when the Sun was condensing,
from a big cloud of gas and dust, small fragments of the cloud started
condensing into millimeter sized objects. These started revolving
around the large central object which would eventually form our Sun.
Their continuous collision in space possibly resulted in the formations
of bigger objects. Ultimately, planet sized bodies were formed. |
In the primitive stages, the Earth was very
hot with lots of gases trapped in between. As time went by, these
gases escaped, forming the atmosphere. This happened approximately
4.5 billion years ago, according to this theory. This hot Earth
slowly cooled and formed a crust. It has a cool crust which extends
from 20 to 50 kms deep. After that a thicker visions mantle and
finally the core which is hot and molten, most probably made up
of iron-nickel compounds.
There are however other theories
and which need not be biased by the above picture which is just
one out about 50 exciting theories of the formation of the Earth
and the Solar System.
The distance between the Earth and the Sun is very unique distance.
The Earth is not too far from the Sun so as to be very cold that
average temperature go below the freezing point of water, neither
it is too close to the Sun for the average temperature to be above
the boiling temperature of water. On Earth daytime temperature is
maximum 58 degree C and night time below 0 degree C i.e. -88 degree
Celcius makes water exist in the liquid form on the Earth. Since
oxygen is also there in the atmosphere, temperature being modest
in its range of variation and if forming carbon compounds are stable,
there conditions subscribe to life - one of their life-forms are
human beings- an intelligent form of life. This makes this planet
the most beautiful place - anywhere in the Universe. It is believed
that the chief constituents of the atmosphere of the Earth about
4 billion years ago where ammonia, methane, carbon dioxide(given
in the order of their abundance) to an observer from space the constantly
changing weather patterns contrast strongly with the fixed surface
features of the continents and the oceans.
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Interesting
Facts:
-Earth is the densest planet in the Solar System
-Earth's four oceans contain 97.2% of the water on our planet
-If all the ice on Earth were to melt, the sea level would rise by
100 m.
-The Earth's polar diameter is 44 km less than its equatorial diameter
-The total surface area of the Earth is 509509000 km of which 70.7%
is water and 29.3% is land. |
Historical Events
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C.22000 B.C. |
Meteor Crater is in Northern
Arizona, US is of 1265 m in diameter and 174 m deep |
22 October 4004 B.C. |
The date of Creation |
22 October 2137 B.C. |
Total Solar Eclipse was
observed |
29 B.C. |
The Chinese began making regular observations
of Sunspots through slices of jade.
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22 March 837 |
The first sighting of Halley's
Comet |
1054 |
The Chinese sighted a "guest
star" in the constellation Taurus, visible in daylight
for 23 days, they see the remnants of a supernova - Crab Nebula |
2 April 1066 |
Halley's Comet
became visible in the Constellation of Pegasus |
September 1608 |
Dutch spectacle
maker Jan Lippershey constructed a telescope. |
30 November,
1609 |
Galileo's first
celestial observations were made with a telescope |
16 March 1926 |
The first liquid
fuel rocket launched by US scientist Robert Goddard. |
4 October 1957 |
The Space Age
officially began in the USSR with successful launch of SPUTNIK. |
4 April 1960 |
The weather
satellite was launched by US, sent back cloud photographs. |
12 August 1960 |
The first communications
satellite Echo 1 was launched |
12 April 1961 |
The first human
in Space was Cosmonaut - Yuri A Gagarin |
20 September,
1966 |
US probe Surveyor
2 failed and crash-landed in oceanus Procellarum |
16 July 1969 |
The first Man
on Moon - Neil A Armstrong, by Apollo 11 launched by US, returned
to Earth 24 July 1969 |
8 December 1990 |
US-European
space probe Gallileo, on its way to Jupiter |
17 February
1998 |
Voyager 1 overtakes
Pioneer 10 as the furthest human-made object from Earth. |
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