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Mercury : Attendant of the Sun
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| Name of
the Planet |
Mercury |
| Position
in Solar System |
Innermost
Planet.Closest to the Sun.First planet in the Solar System |
| Constituents |
Rocky,
Ferrous |
| Atmosphere |
Almost
none |
| Average
Distance from Sun |
58,000,000
km/36,000,000 mi |
| Orbit
Time |
0.241
Earth years |
| Diameter |
4,880
km/3,030 mi |
| Average
Density (water=1) |
5.4 |
| Satellites |
none
|
| Average
Surface Temp |
179ºC
|
| Rotational
Period |
58.65
days |
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Description:
Mercury is the innermost
planet of the Solar System and is the closest of all planets to
the Sun. Mercury has a diameter of about 4,880 km and is at a distance
of about 58 million kms from the Sun. Its size and close proximity
to the Sun makes it a difficult planet to study from the Earth.
However as far as the recorded history goes, Mercury has been known
since 264 B.C when it was observed and recorded by the Babylonians.
The Greeks called it 'Stillborn' the twinkler.
Recent studies by space crafts,
particularly Mariner 10 have tremendously increased our knowledge
of Mercury. In 1974, Mariner 10 sent back the first detailed pictures
of mercury. The pictures show a surface strewn with craters. These
surface features probably took shape early in Mercury's history,
when rocky materials up to several km in diameter crashed into the
young planet forming these craters. Between many of the craters
are smooth plains, perhaps caused by the volcanoes. Mercury is covered
with craters, caused by heavy meteoric bombardment very similar
to that which was experienced by the Moon. The space craft Mariner
10 obtained the mosaic of views of Mercury during March 1974. A
relatively new crater about 12 km across, lies within an old crater
basin. This picture was taken from a distance of about 20,700 km.
The planet may have an iron
core about as big as the Moon's core which is surrounded by a thin
silicate mantle and rigid silicate crust. Mercury is almost as dense
as the Earth, and its surface gravity is about a third that of Earth.
During the day, temperature
on Mercury reaches about 427 degrees C making it so hot that even
lead would melt. While at night, the temperature plunges to about
-173 degrees C. Mercury goes around the Sun in only 88 days i.e.
one year on Mercury is about 88 Earth days. It rotates once about
its axis in 59 Earth days. This means that every time Mercury makes
two revolutions, it has made only about three rotations. As a result
of its short year, you could be one year older every 88 days, if
you were a Mercurian!
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Interesting Facts:
-Mercury has a total of 297 named features,
of which 239 are craters.
-The largest crater on Mercury is Bethoveen with a diameter
of 643 km, it is the largest crater in the Solar System.
-From Mercury, the Sun is 6.3 times brighter than from Earth.The
light from the Sun takes takes on average 3 minutes 13 seconds
to reach Mercury.
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Historical Events
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| C.385B.C. |
The Greek astronomer Heraclides
became the first person to suggest that Mercury orbits the Sun |
| 7 Nov. 1631 |
Using predictions made by
Johannes Kepler the French astronomer Pierre Gassendi became
the first to obeserve a transit of Mercury |
| 1878 |
US astronomer Samuel Pierpont
Langley was the first to see Mercury against the Solar corona. |
| 1889 |
William Harkness measured
the mass of Mercury.Giovanni Schiaparelli announced the rotational
rate of Mercury as 88 days. |
| 1962 |
The first radar contact
with Mercury was established by the radio telescope at Arecibo,
Puerto Rico |
| 1971 |
D Goldstein refined the
rotational rate of Mercury to 58.65 days. |
| 29 March,1974 |
Mariner 10 encountered Mercury
for the first time.On 16 March,1975, the third and final encounter
of Mercury by Mariner 10. |
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