General Knowledge of Solar System Complete
The
Solar System comprises the Sun and the objects that orbit it, either directly
or indirectly. Of those objects that orbit the Sun directly, the largest eight
are the planets that form the planetary system around it, while the
remainder are significantly smaller objects, such as dwarf planets and small
Solar System bodies such as comets and asteroids.
• The solar system is the family of the sun, planets revolving around
it, the satellites of the planets and the asteroids or meteoroids and comets etc.
Inner Solar System
The inner Solar System is the traditional name for the
region comprising the terrestrial planets and asteroids.[59] Composed mainly of
silicates and metals, the objects of the inner Solar System are relatively
close to the Sun; the radius of this entire region is less than the distance
between the orbits of Jupiter and Saturn. This region is also within the frost
line, which is a little less than 5 AU (about 700 million km) from the Sun.
Mercury
Mercury (0.4 AU from the Sun) is the closest planet to the
Sun and the smallest planet in the Solar System (0.055 Earth masses). Mercury
has no natural satellites; besides impact craters, its only known geological
features are lobed ridges or rupes that were probably produced by a period of
contraction early in its history. Mercury's very tenuous atmosphere consists of
atoms blasted off its surface by the solar wind. Its relatively large iron core
and thin mantle have not yet been adequately explained. Hypotheses include that
its outer layers were stripped off by a giant impact; or, that it was prevented
from fully accreting by the young Sun's energy. read more about mercury
Venus
Venus (0.7 AU from the Sun) is close in size to Earth (0.815
Earth masses) and, like Earth, has a thick silicate mantle around an iron core,
a substantial atmosphere, and evidence of internal geological activity. It is
much drier than Earth, and its atmosphere is ninety times as dense. Venus has
no natural satellites. It is the hottest planet, with surface temperatures over
400 °C (752°F), most likely due to the amount of greenhouse gases in the
atmosphere. No definitive evidence of current geological activity has been
detected on Venus, but it has no magnetic field that would prevent depletion of
its substantial atmosphere, which suggests that its atmosphere is being replenished
by volcanic eruptions.
Earth
Earth (1 AU from the Sun) is the largest and densest of the
inner planets, the only one known to have current geological activity, and the
only place where life is known to exist. Its liquid hydrosphere is unique among
the terrestrial planets, and it is the only planet where plate tectonics has
been observed. Earth's atmosphere is radically different from those of the
other planets, having been altered by the presence of life to contain 21% free
oxygen. It has one natural satellite, the Moon, the only large satellite of a
terrestrial planet in the Solar System.
Mars
Mars (1.5 AU from the Sun) is smaller than Earth and Venus
(0.107 Earth masses). It possesses an atmosphere of mostly carbon dioxide with
a surface pressure of 6.1 millibars (roughly 0.6% of that of Earth).[69] Its
surface, peppered with vast volcanoes, such as Olympus Mons, and rift valleys,
such as Valles Marineris, shows geological activity that may have persisted
until as recently as 2 million years ago.[70] Its red colour comes from iron
oxide (rust) in its soil Mars has two tiny natural satellites (Deimos and
Phobos) thought to be captured asteroids. read more about mars
Outer Solar System
The outer region of the Solar System is home to the giant
planets and their large moons. The centaurs and many short-period comets also
orbit in this region. Due to their greater distance from the Sun, the solid
objects in the outer Solar System contain a higher proportion of volatiles,
such as water, ammonia, and methane than those of the inner Solar System
because the lower temperatures allow these compounds to remain solid.
Jupiter
Jupiter (5.2 AU), at 318 Earth masses, is 2.5 times the mass
of all the other planets put together. It is composed largely of hydrogen and
helium. Jupiter's strong internal heat creates semi-permanent features in its
atmosphere, such as cloud bands and the Great Red Spot. Jupiter has 67 known
satellites. The four largest, Ganymede, Callisto, Io, and Europa, show
similarities to the terrestrial planets, such as volcanism and internal
heating. Ganymede, the largest satellite in the Solar System, is larger than
Mercury.
Saturn
Saturn (9.5 AU), distinguished by its extensive ring system,
has several similarities to Jupiter, such as its atmospheric composition and
magnetosphere. Although Saturn has 60% of Jupiter's volume, it is less than a
third as massive, at 95 Earth masses, making it the least dense planet in the
Solar System. The rings of Saturn are made up of small ice and rock particles.
Saturn has 62 confirmed satellites; two of which, Titan and Enceladus, show
signs of geological activity, though they are largely made of ice.[86] Titan,
the second-largest moon in the Solar System, is larger than Mercury and the
only satellite in the Solar System with a substantial atmosphere.
Uranus
Uranus (19.2 AU), at 14 Earth masses, is the lightest of the
outer planets. Uniquely among the planets, it orbits the Sun on its side; its
axial tilt is over ninety degrees to the ecliptic. It has a much colder core
than the other giant planets and radiates very little heat into space. Uranus has 27 known satellites, the largest
ones being Titania, Oberon, Umbriel, Ariel, and Miranda.
Neptune
Neptune (30.1 AU), though slightly smaller than Uranus, is
more massive (equivalent to 17 Earths) and hence more dense. It radiates more
internal heat, but not as much as Jupiter or Saturn. Neptune has 14 known
satellites. The largest, Triton, is geologically active, with geysers of liquid
nitrogen.[89] Triton is the only large satellite with a retrograde orbit. Neptune
is accompanied in its orbit by several minor planets, termed Neptune trojans,
that are in 1:1 resonance with it.
Pluto
The dwarf planet Pluto (39 AU average) is the largest known
object in the Kuiper belt. When discovered in 1930, it was considered to be the
ninth planet; this changed in 2006 with the adoption of a formal definition of
planet. Pluto has a relatively eccentric orbit inclined 17 degrees to the
ecliptic plane and ranging from 29.7 AU from the Sun at perihelion (within the
orbit of Neptune) to 49.5 AU at aphelion.
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