System is made up of all the planets that orbit our Sun. In addition to
planets, the Solar System also consists of moons, comets, asteroids,
minor planets, and dust and gas. Each of
these bodies is held to each other by the force of
in the Solar System orbits or revolves around the Sun. The Sun contains
around 98% of all the material in the Solar System. The larger an object
is, the more gravity it has. Because the Sun is so large, its powerful
gravity attracts all the other objects in the Solar System towards it.
At the same time, these objects, which are moving very rapidly, try to
fly away from the Sun, outward into the emptiness of outer space. The
result of the planets trying to fly away, at the same time that the Sun
is trying to pull them inward is that they become trapped half-way in
between. Balanced between flying towards the Sun, and escaping into
space, they spend eternity orbiting around their parent star.
The sun is
by far the largest part of the solar system. The other principal members
of the solar system are the nine major planets.
are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and
Pluto (which is now considered a dwarf planet). The planets orbiting
nearer the sun than the earth are called inferior planets; those whose
orbits are larger are called superior planets. The unit for measuring
distance in the solar system is the astronomical unit (A.U.), the
average distance between the earth and the sun. The mean distances of
the planets from the sun range from 0.39 A.U. for Mercury to 39 A.U. for
The Solar System form?
This is an
important question, and one that is difficult for scientists to
understand. After all, the creation of our Solar System took place
billions of years before there were any people around to witness it. Our
own evolution is tied closely to the evolution of the Solar System.
Thus, without understanding from where the Solar System came from, it is
difficult to comprehend how mankind came to be.
believe that the Solar System evolved from a giant cloud of dust and
gas. They believe that this dust and gas began to collapse under the
weight of its own gravity. As it did so, the matter in this could begin
moving in a giant circle, much like the water in a drain moves around
the center of the drain in a circle.
center of this spinning cloud, a small star begin to form. This star
grew larger and larger, as it collected more of the dust and gas that
were collapsing into it.
away from the star that was forming in the center were smaller clumps of
dust and gas that were also collapsing. The star in the center
eventually ignited forming our Sun, while the smaller clumps became the
planets, minor planets, moons, comets, and asteroids.
is the innermost and smallest
once every 88 days. It can only be seen in morning or evening
Comparatively little is known about the planet. Physically, Mercury is
similar in appearance to the
as it is heavily
It has no
and no substantial
named the planet after the fleet-footed messenger
probably for its fast apparent motion in the twilight sky.
Venus is the
second-closest planet to the Sun, orbiting it every 224.7 Earth days. It
is the brightest natural object in the night sky, except for the Moon.
Because Venus is an inferior planet, from Earth it never appears to
venture far from the Sun. Venus reaches its maximum brightness shortly
before sunrise or shortly after sunset, for which reason it is often
called the Morning Star or the Evening Star. The planet is
named after Venus, the Roman goddess of love; most of its surface
features are named after famous and mythological women.
The earth rotates or turns
from west to east about a line called its axis. The period of one
complete rotation is a day. Because of the rotation of the earth we
experience light and darkness (day and night). The earth revolves about
the sun once every 365 1/4 days which is a year. The path of this
revolution, the earth's orbit, is an oval in shape. This means the earth
is closer to the sun in January than it is in July.
The change in seasons is
caused by the tilt of the earth on its axis. When the northern end of
the earth's axis is toward the sun, the most direct rays of sunlight
fall in the Northern Hemisphere. This causes its summer season. At the
same time the Southern Hemisphere has winter since it is then receiving
indirect rays. Halfway between, in spring and in autumn, there is a time
called the equinox when all parts of the earth have equal day and night.
When the northern end of the earth's axis is tilted away from the sun,
the least direct sunlight falls on the Northern Hemisphere. This causes
Mars is the fourth
planet from the Sun and is known as the Red Planet due to its
reddish appearance as seen from Earth. The planet is named after Mars,
the Roman god of war. A terrestrial planet, Mars has a thin atmosphere
and surface features reminiscent both of the impact craters of the Moon
and the volcanoes, valleys, deserts and polar ice caps of Earth. It has
the highest mountain in the solar system, Olympus Mons, and the largest
canyon, Valles Marineris. Mars' rotational period and seasonal cycles
are also similar to those of the Earth. Mars has two moons, Phobos and
Deimos, which are small and oddly shaped. Mars can be seen from Earth
with the naked eye.
Jupiter is the
fifth planet from the Sun and the largest planet within the solar
system. It is two and a half times as massive as all of the other
planets in our solar system combined. Jupiter, along with Saturn,
Uranus, and Neptune, is classified as a gas giant. Together, these four
planets are sometimes referred to as the Jovian planets. The Romans
named it after Jupiter, the principal God of Roman mythology, whose name
is a reduction of 'Deus Pater', meaning 'God father'.
named for the Greek word, meaning "heaven" or "sky" is the seventh
It is a
the third largest by
and fourth largest by
It is named after
the Greek god of the sky and progenitor of the other gods. Uranus is the
first planet discovered in modern times. Sir
formally discovered the planet on
the other planets (from
have been known since ancient times, since they are visible to the naked
eye. Uranus' discovery expanded the boundaries of the
for the first time in modern human history. It was also the first planet
rather than the
Neptune is the
eighth and farthest planet from the Sun in our solar system. IT is the
fourth largest planet by diameter and the third largest by mass; Neptune
is 17 times the mass of Earth and is slightly more massive than its near
twin Uranus, which is 14 Earth masses, but slightly smaller due to its
higher density. The planet is named after the Roman god of the sea.
Neptune's atmosphere is primarily composed of hydrogen and helium, with
traces of methane that account for the planet's blue appearance. Neptune
also has the strongest winds of any planet in the solar system, measured
as high as 2,100km/h. Discovered on September 23, 1846, Neptune is
notable for being the first planet discovered based on mathematical
prediction rather than regular observations.
also designated 134340 Pluto, is the second-largest known
and the tenth largest observed body directly orbiting the Sun.
Approximately one-fifth the mass of the
Pluto is primarily composed of rock and ice. It has an
that is highly inclined with respect to the planets and takes it closer
to the Sun than
during a portion of its orbit.