Download Composition Of The Solar System

The Solar System
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Our solar system consists of an average star we call the Sun, the planets Mercury,
Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It includes: the
satellites of the planets; numerous comets, asteroids, and meteoroids; and the
interplanetary medium. The Sun is the richest source of electromagnetic energy (mostly
in the form of heat and light) in the solar system. The Sun's nearest known stellar
neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years
away. The whole solar system, together with the local stars visible on a clear night,
orbits the center of our home galaxy, a spiral disk of 200 billion stars we call the
Milky Way. The Milky Way has two small galaxies orbiting it nearby, which are
visible from the southern hemisphere. They are called the Large Magellanic Cloud and
the Small Magellanic Cloud. The nearest large galaxy is the Andromeda Galaxy. It is
a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light years
away.
The planets, most of the satellites of the planets and the asteroids revolve around the
Sun in the same direction, in nearly circular orbits. When looking down from above the
Sun's north pole, the planets orbit in a counter-clockwise direction. The planets orbit
the Sun in or near the same plane, called the ecliptic. Pluto is a special case in that its
orbit is the most highly inclined (18 degrees) and the most highly elliptical of all the
planets. Because of this, for part of its orbit, Pluto is closer to the Sun than is Neptune.
The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The
exceptions are Uranus and Pluto, which are tipped on their sides.
Composition Of The Solar System
The Sun contains 99.85% of all the matter in
the Solar System. The planets, which
condensed out of the same disk of material that
formed the Sun, contain only 0.135% of the
mass of the solar system. Jupiter contains more
than twice the matter of all the other planets
combined. Satellites of the planets, comets,
asteroids, meteoroids, and the interplanetary
medium constitute the remaining 0.015%. The
following table is a list of the mass distribution
within our Solar System.
*
*
*
*
*
*
*
Sun: 99.85%
Planets: 0.135%
Comets: 0.01% ?
Satellites: 0.00005%
Minor Planets: 0.0000002% ?
Meteoroids: 0.0000001% ?
Interplanetary Medium: 0.0000001% ?
Interplanetary Space
Nearly all the solar system by volume appears to be an empty void. Far from being nothingness, this vacuum
of "space" comprises the interplanetary medium. It includes various forms of energy and at least two material
components: interplanetary dust and interplanetary gas. Interplanetary dust consists of microscopic
solid particles. Interplanetary gas is a tenuous flow of gas and charged particles, mostly protons and electrons
-- plasma -- which stream from the Sun, called the solar wind. The solar wind can be measured by
spacecraft, and it has a large effect on comet tails. It also has a measurable effect on the motion of spacecraft.
The speed of the solar wind is about 400 kilometers (250 miles) per second in the vicinity of Earth's orbit.
The Terrestrial Planets: The Inner Planets
The terrestrial planets are the four
innermost planets in the solar system,
Mercury, Venus, Earth and Mars.
They are called terrestrial because they
have a compact, rocky surface like the
Earth's. The planets, Venus, Earth, and
Mars have significant atmospheres while
Mercury has almost none. The following
diagram shows the approximate distance
of the terrestrial planets to the Sun.
The Jovian Planets: The Outer Planets
Jupiter, Saturn, Uranus, and Neptune
are known as the Jovian (Jupiter-like)
planets, because they are all gigantic
compared with Earth, and they have a
gaseous nature like Jupiter's. The Jovian
planets are also referred to as the gas
giants, although some or all of them might
have small solid cores. The following
diagram shows the approximate distance of
the Jovian planets to the Sun. (photo Copyright
Calvin J. Hamilton)
Our Milkyway Galaxy
This image of our galaxy, the Milky Way, was taken with NASA's Cosmic
Background Explorer's (COBE) Diffuse Infrared Background Experiment
(DIRBE). This never-before-seen view shows the Milky Way from an edgeon perspective with the galactic north pole at the top, the south pole at the
bottom and the galactic center at the center. The picture combines images
obtained at several near-infrared wavelengths. Stars within our galaxy are the
dominant source of light at these wavelengths. Even though our solar system
is part of the Milky Way, the view looks distant because most of the light
comes from the population of stars that are closer to the galactic center than
our own Sun. (Courtesy NASA)
Spiral Galaxy, NGC 4414
The majestic galaxy, NGC 4414, is located 60 million light-years away.
Like the Milky Way, NGC 4414 is a giant spiral-shaped disk of
stars, with a bulbous central hub of older yellow and red stars. The
outer spiral arms are considerably bluer due to ongoing formation of
young, blue stars, the brightest of which can be seen individually at the
high resolution provided by the Hubble camera. The arms are also very
rich in clouds of interstellar dust, seen as dark patches and streaks
silhouetted against the starlight. (Courtesy NASA/STSCI)
Obliquity of the Nine Planets
This illustration shows the obliquity of the nine planets. Obliquity is the angle between a planet's
equatorial plane and its orbital plane. By International Astronomical Union (IAU) convention, a planet's
north pole lies above the ecliptic plane. By this convention, Venus, Uranus, and Pluto have a retrograde
rotation, or a rotation that is in the opposite direction from the other planets.(Copyright Calvin J. Hamilton)
The Solar System
During the past three decades a myriad of space explorers have
escaped the confines of planet Earth and have set out to
discover our planetary neighbors. This picture shows the Sun
and all nine planets of the solar system as seen by the space
explorers. Starting at the top-left corner is the Sun followed
by the planets Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, Neptune, and Pluto. (Copyright 1998 by Calvin J.
Hamilton)
The Largest Moons and Smallest Planets
This image shows the relative sizes of the largest moons and the smallest
planets in the solarsystem. The largest satellites pictured in this image are:
Ganymede (5262 km), Titan (5150 km), Callisto (4806 km), Io (3642 km),
the Moon (3476 km), Europa (3138 km), Triton (2706 km), and Titania
(1580 km). Both Ganymede and Titan are larger than planet Mercury
followed by Io, the Moon, Europa, and Triton which are larger than the
planet Pluto. (Copyright Calvin J. Hamilton)