OUR SOLAR
SYSTEM
The Sun, Planets and Dwarf Planets
FACTS ABOUT OUR SOLAR
SYSTEM
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The Solar System consists of the Sun and its planetary system of eight planets,
their moons, and other non-stellar objects.
It formed 4.6 billion years ago from the collapse of a giant molecular cloud. The
vast majority of the system's mass is in the Sun, with most of the remaining mass
contained in Jupiter.
The four smaller inner planets, Mercury, Venus, Earth and Mars, also called the
terrestrial planets, are primarily composed of rock and metal.
The four outer planets, called the gas giants, are substantially more massive than
the terrestrials.
The two largest, Jupiter and Saturn, are composed mainly of hydrogen and helium;
the two outermost planets, Uranus and Neptune, are composed largely of ices,
such as water, ammonia and methane, and are often referred to separately as "ice
giants".
All planets have almost circular orbits.
THE SUN
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Evidence suggests that the Sun's position on the main sequence puts it in the
"prime of life" for a star, in that it has not yet exhausted its store of hydrogen for
nuclear fusion.
The Sun is growing brighter; early in its history it was 70 percent as bright as it is
today.
The Sun is was born in the later stages of the universe's evolution, and thus
contains more elements heavier than hydrogen and helium ("metals" in
astronomical parlance) than older population II stars.
Elements heavier than hydrogen and helium were formed in the cores of ancient
and exploding stars, so the first generation of stars had to die before the universe
could be enriched with these atoms.
The oldest stars contain few metals, while stars born later have more. This high
metallicity is thought to have been crucial to the Sun's developing a planetary
system, because planets form from accretion of "metals".
PLANETS CLOSE TO THE
SUN
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MERCURY
Mercury is the closest planet to the
Sun, the distance between them is
0.4 AU
It is the smallest planet in our
Solar System (0.055 Earth masses)
It doesn’t have any natural
satellites
It has a relatively large iron core
and thin mantle, which have not
been adequately explained yet
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VENOUS
Venous is 0.7 AU close to
the Sun
It is close in size to Earth
(0.8015 Earth masses)
It has no natural satellites
It is the hottest planet in our
Solar System, 400 °C and it’s
also much drier than Earth
It has no magnetic field
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EARTH
Earth is 1 AU close to the Sun
It is the largest and the densest of
the four planets, Mercury, Venous,
Mars
It is the only planet that in our
Solar System where life exist
It’s the only planet where water
can be found
It’s atmosphere is different from
the other planets, because it
contains 21% oxygen in order to
life existence
It has a natural satellite, Moon.
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MARS
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Mars is 1.5AU away from the Sun
It is smaller than Earth (0.5 Earth
masses)
It’s atmosphere contains mostly
carbon dioxide
It’s surface pressure is 6.1
millibars (0.6 percent of Earth’s)
It’s red color is from the iron oxide
It has two natural satellites,
Deimos and Phobos, which are
very tiny
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PLANETS FAR FROM THE
SUN
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JUPITER
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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 a
number of 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.
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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.
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.
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URANUS
Uranus (19.6 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 gas giants, and radiates very
little heat into space.
Uranus has 27 known satellites, the
largest ones being Titania, Oberon,
Umbriel, Ariel and Miranda.
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NEPTUNE
Neptune (30 AU), though slightly smaller
than Uranus, is more massive (equivalent
to 17 Earths) and therefore more dense.
It radiates more internal heat, but not as
much as Jupiter or Saturn.
Neptune has 13 known satellites.
The largest, Triton, is geologically active,
with geysers of liquid nitrogen.
Triton is the only large satellite with a
retrograde orbit. Neptune is accompanied
in its orbit by a number of minor planets,
termed Neptune trojans, that are in 1:1
resonance with it.
DWARF PLANETS
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A dwarf planet, as defined by the International Astronomical Union
(IAU), is a celestial body in direct orbit of the Sun that is massive
enough that its shape is controlled by gravitational forces rather than
mechanical forces (and is thus an ellipsoid), but has not cleared the
neighboring region of other objects.
More explicitly, it is a planetary-mass object—it has sufficient mass to
overcome its internal compressive strength and achieve hydrostatic
equilibrium—but is neither a planet nor a satellite.
The term dwarf planet was adopted in 2006 as part of a three-way
categorization of bodies orbiting the Sun, brought about by an increase
in discoveries of trans-Neptunian objects that rivaled Pluto in size, and
finally precipitated by the discovery of an even more massive object,
Eris.
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PLUTO
Pluto is 39 AU away of Sun
It is the largest dwarf planet
in the Kuiper belt
It was discovered in 1930
It is no longer thought to be
a normal planet in our Solar
System, but a dwarf
It’s largest moon, Charon,
has an almost same mass
with it
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MAKEMAKE
Makemake is 45.79 AU
away from the Sun
It is smaller than Pluto
It is the brightest object in
Kuiper belt after Pluto
It was named a dwarf
planet in 2008
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HAUMEA
The distance between
Haumea and Sun is 43.13
AU
It is about the same size as
Makemake
It has two natural satellites
It was named a dwarf
planet in 2008