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The
Solar System Our
solar system consists of
one star, the Sun, eight
major planets, their moons
and thousands of smaller
bodies including asteroids,
comets and meteors. Until
2006 there were assumed to
be nine planets though in
that year Pluto was excluded
because it shares Neptune's
orbit for a part of the time.
A planet must have a unique
orbit according to the scientific
community The
Sun is the only body in our
solar system that has any
light of its own with the
rest simply reflecting its
rays. The
Sun is one of the smaller
known stars and is made up
of a mass of hot gasses. More
than a million times larger
than Earth, the Sun is nearly
300 000 times as heavy. Light
from the Sun takes around
eight and a half minutes
to reach Earth where rays
from our next nearest star,
Proxima Centauri, takes more
than 4 years. The
Sun's surface is estimated
to be 10 800 F and is called
the photosphere and is surrounded
by a crimson gas called chromosphere. The
Sun provides us with the
light and heat that is essential
to our existence as well
as providing us with a gravitational
anchor that helps us retain
those essentials. Mercury
is the smallest of the known
planets of our Solar System
and is less than half the
size of Earth. It was considered at one time that one
side of Mercury always faces
the Sun and its surface reaches
temperatures of up to 380
C whilst the other side is
intensely cold. This is incorrect. In
its early days Mercury's
gravity was unable to hold
onto its gasses and they
boiled off. The planet, then,
has no real atmosphere except
for a few traces of carbon
dioxide. Mercury
has no moons. The
second planet from the Sun
is Venus which is much the
same size as the Earth. After
sunset Venus is known as
the Evening Star and just
before sunrise as the Morning
Star. Scientists
cannot determine the actual
length of a Venus day because
the planet is constantly
covered by dense cloud though
it is estimated to be around
30 Earth days. Venus
is the bright white 'star'
that is the first to appear
after sunset, long before
any other star is visible. Venus
has no moons. As
beautiful as it is, Earth
is not the 'centre of the
universe'. It is simply one
of the smaller planets in
our Solar System. Although
it does maintain intelligent
life I believe it would be
most unintelligent of us
to just assume that it is
the only such body in the
vastness of the Universe. Earth
is the third planet from
the Sun and over two thirds
of its surface is covered
with water. Its atmosphere,
composed mainly of oxygen
and nitrogen, results in
the relatively moderate temperature
range over much of the planet. Earth
has one moon. The
forth planet from the sun
is Mars which is just over
one tenth the size of Earth. Mars
takes 687 Earth days to circle
the Sun and it revolves on
its axis each 24 1/2 hours.
It has seasons just as on
Earth, though they are around
twice as long as ours. At
its equator the planet's
temperatures reach almost
27C with its nights being
extremely cold. Mars
is considered the planet,
apart from Earth, most likely
to support life as we know
it. The
planet's atmosphere is made
up of a small amount of oxygen
with most of the rest being
nitrogen. Mars
has two moons: Phobos and
Deimos. Jupiter
is the fifth planet out from
the Sun and is the giant
of the solar system. Jupiter's
atmosphere is made up mainly
of hydrogen, methane, and
ammonia with an average temperature
of minus 130 C and is divided
into several broad bands
each moving at different
speeds. The
bands are constantly changing
colour but their number always
remains the same. Although
the surface can not be examined
by telescope, because of
the dense cloud cover, scientists
claim that the surface is
covered by a layer of ice
that is possibly 27 000 Km
thick. Jupiter
has 12 moons including Amalthea,
Lo, Europa, Ganymede and
Callisto with the rest unnamed. Saturn
is the sixth planet out from
the sun and is the one with
the rings around it. Although
Saturn is some 750 times
bigger than Earth its gravitational
force is only marginally
greater (1.17 times) as it
is not packed as tightly
as Earth. The
atmosphere is similar to
that of Jupiter made up mainly
of hydrogen, methane and
ammonia below which is a
deep layer of ice. Saturn's
three rings measure over
273 000 Km edge to edge and
between 16 and 64 Km deep
and are believed to consist
of small pieces of ice encrusted
rock. Saturn
has nine moons including
Mimas, Enceladus, Tethys,
Dione, Rhea, Titan, Hyperion,Iapetus
and Phoebe. Titan, a massive
5 630 Km in diameter, is
believed to be the only moon
to possess its own gravity. Seventh
out from the Sun is Uranus
which, although it can just
be seen with the naked eye,
was only discovered in 1781 Seen
through a telescope Uranus
is a pale green disk without
distinct surface markings. The
axis of Jupiter is deeply
tilted and where Earth is
tilted by twenty three and
a half degrees, Jupiter is
ninety eight degrees. One
result of this tilting is
that the planet is often
seen end on with its north
pole toward us and its moons
appear to act strangely. Uranus
has an extremely poisonous
methane atmosphere and surface
temperatures of minus 190
C. The
planet's five moons are Miranda,
Ariel, Umbriel, Titania and
Oberon. Eighth
out from the Sun, Neptune
is another of the giant planets
and was discovered in 1846. Scientists
were attempting to explain
the irregular movements of
Uranus that could only be
explained by the existence
of another planet. Neptune
takes some 165 years to orbit
the Sun and has an atmosphere
of mainly methane with clouds
of ammonia crystals. Neptune
has two moons called Triton
and Nereid. Predicted
by the astronomer, Lowell,
in 1905 it was not until
1930 that Pluto was actually
observed by Clyde Tombaugh. Pluto
takes around 250 years to
orbit the Sun and as a result
of its highly elliptical
orbit is occasionally closer
to the Sun than Neptune leading
some astronomers to presume
that it is not a planet but
a breakaway, rogue moon of
Neptune. Little
is known of Pluto though
it is believed to be extremely
cold and have no moons.
from Sun
(million km)
at equator
(km)
(Earth = 1)
It is the nearest planet to
the Sun and travels in an elongated
orbit around the Sun taking
88 Earth days.
from Sun
(million km)
at equator
(km)
(Earth = 1)
from Sun
(million km)
at equator
(km)
(Earth = 1)
from Sun
(million km)
at equator
(km)
(Earth = 1)
from Sun
(million km)
at equator
(km)
(Earth = 1)
from Sun
(million km)
at equator
(km)
(Earth = 1)
from Sun
(million km)
at equator
(km)
(Earth = 1)
from Sun
(million km)
at equator
(km)
(Earth = 1)
(No
longer considered to be a planet)
from
Sun
(million
km)
at
equator
(km)
(Earth
=
1)
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