Download Space and planets

Space and planets
By Ruby
Contents
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Introduction
Earth
Mercury
Pluto
Neptune
The sun
The moon
Mars
Saturn
Jupiter
Uranus
Venus
Comets
Asteroids
The end
Earth
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Earth is the third planet from the
Sun, and the largest of the
terrestrial planets in the Solar
System in terms of diameter, mass
and density. It is also referred to
as the World and Terra. Earth has
been referred to as the Blue
Planet due to the abundant water
on its surface and/or the
atmospheric hue.
Home to millions of species
including humans, Earth is the
only place in the universe where
life is known to exist. The planet
formed 4.54 billion years ago and
life appeared on its surface within
a billion years.
Mercury
• Mercury is the
innermost and
smallest planet in the
Solar System orbiting
the Sun once every
88 days. The orbit of
Mercury has the
highest eccentricity of
all the Solar System
planets, and it has the
smallest axial tilt.
Pluto
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Pluto, is the second-largest known
dwarf planet in the Solar System (after
Eris) and the tenth-largest body
observed directly orbiting the Sun.
Originally classified as a planet, Pluto
is now considered the largest member
of a distinct population called the
Kuiper belt.[9]
Like other members of the Kuiper belt,
Pluto is composed primarily of rock
and ice and is relatively small:
approximately a fifth the mass of the
Earth's Moon and a third its volume. It
has an eccentric and highly inclined
orbit that takes it from 30 to 49 AU
(4.4–7.4 billion km) from the Sun. This
causes Pluto periodically to come
closer to the Sun than Neptune.
Neptune
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Neptune is the eighth planet from the
Sun in the Solar System. Named for
the Roman god of the sea, 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 neartwin Uranus, which is 15 Earth masses
and not as dense. On average,
Neptune orbits the Sun at a distance
of 30.1 , approximately 30 times the
Earth-Sun distance. Its astronomical
symbol is , a stylized version of the
god Neptune's trident.
Discovered on September 23, 1846,
Neptune was the first planet found by
mathematical prediction rather than by
empirical observation. Unexpected
changes in the orbit of Uranus led
astronomers to deduce that its orbit
was subject to gravitational
perturbation by an unknown planet.
The sun
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The Sun, a yellow dwarf, is the
star at the centre of the Solar
System. The Earth and other
matter (including other planets,
asteroids, meteoroids, comets,
and dust) orbit the Sun, which by
itself accounts for about 98.6% of
the Solar System's mass. The
mean distance of the Sun from the
Earth is approximately
149,600,000 kilometres
(93,000,000 mi), and its light
travels this distance in 8 minutes
and 19 seconds. Energy from the
Sun, in the form of sunlight,
supports almost all life on Earth
via photosynthesis, and drives the
Earth's climate and weather.
The Moon
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The Moon is Earth's only natural
satellite and the fifth largest
satellite in the Solar System. The
average centre-to-centre distance
from the Earth to the Moon is
384,403 km, about thirty times the
diameter of the Earth. The
common centre of mass of the
system (the barycentre) is located
about 1,700 km—a quarter the
Earth's radius—beneath the
surface of the Earth. The Moon
makes a complete orbit around
the Earth every 27.3 days and the
periodic variations in the geometry
of the Earth–Moon–Sun system
are responsible for the lunar
phases that repeat every
29.5 days.
Mars
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Mars (pronounced /ˈmars/) is the fourth
planet from the Sun in the Solar System.
The planet is named after Mars, the Roman
god of war. It is also referred to as the "Red
Planet" because of its reddish appearance,
due to iron oxide prevalent on its surface.
Mars is a terrestrial planet with a thin
atmosphere, having surface features
reminiscent both of the impact craters of the
Moon and the volcanoes, valleys, deserts
and polar ice caps of Earth. It is the site of
Olympus Mons, the highest known mountain
in the Solar System, and of Valles Marineris,
the largest canyon. Furthermore, in June
2008 three articles published in Nature
presented evidence of an enormous impact
crater in Mars' northern hemisphere,
10,600 km long by 8,500 km wide, or
roughly four times larger than the largest
impact crater yet discovered, the South
Pole-Aitken basin.[6][7] In addition to its
geographical features, Mars’ rotational
period and seasonal cycles are likewise
similar to those of Earth.
Saturn
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Saturn ( /ˈsætɚn/ (help·info)[10]) is the
sixth planet from the Sun and the second
largest planet in the Solar System, after
Jupiter. Saturn, along with Jupiter, Uranus
and Neptune, is classified as a gas giant.
Together, these four planets are sometimes
referred to as the Jovian, meaning "Jupiterlike", planets.
Saturn is named after the Roman god
Saturn's (that became the namesake of
Saturday), equated to the Greek Kronos (the
Titan father of Zeus) the Babylonian Minute
and to the Hindu Shani. Saturn's symbol
represents the god's sickle (Unicode: ♄).
The planet Saturn is composed of hydrogen,
with small proportions of helium and trace
elements.[11] The interior consists of a small
core of rock and ice, surrounded by a thick
layer of metallic hydrogen and a gaseous
outer layer.
Jupiter
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Jupiter, is the fifth planet from the Sun and
the largest planet within the Solar System. It
is a gas giant with mass slightly less than
one thousandth that of the Sun but is two
and a half times more massive than all of
the other planets in our Solar System
combined. Jupiter is classified as a gas giant
along with Saturn, Uranus and Neptune.
Together, these four planets are sometimes
referred to as the Jovian planets.
The planet was known by astronomers of
ancient times and was associated with the
mythology and religious beliefs of many
cultures. The Romans named the planet
after the Roman god Jupiter. When viewed
from Earth, Jupiter can reach an apparent
magnitude of −2.8, making it on average the
third-brightest object in the night sky after
the Moon and Venus. (Mars can briefly
exceed Jupiter's brightness at certain points
in its orbit.)
Uranus
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Uranus is the seventh planet from
the Sun and the third-largest and
fourth most massive planet in the
Solar System. It is named after the
ancient Greek deity of the sky
Uranus (Ancient Greek) the father
of Kronos (Saturn) and
grandfather of Zeus (Jupiter).
Though it is visible to the naked
eye like the five classical planets,
it was never recognized as a
planet by ancient observers
because of its dimness and slow
orbit. Sir William Herschel
announced its discovery on March
13, 1781, expanding the known
boundaries of the solar system for
the first time in modern history.
This was also the first discovery of
a planet made using a telescope.
Venus
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Venus is the second-closest
planet to the Sun, orbiting it every
224.7 Earth days. The planet is
named after Venus, the Roman
goddess of love. Except for the
Moon it is the brightest natural
object in the night sky, reaching an
apparent magnitude of −4.6.
Because Venus is an inferior
planet from Earth, it never
appears to venture far from the
Sun: its elongation reaches a
maximum of 47.8°. 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.
Comets
• A comet is a Small Solar
System Body that orbits the
Sun. When close enough to
the Sun, a comet exhibits a
visible coma (fuzzy
"atmosphere"), and sometimes
a tail, both because of the
effects of solar radiation upon
the comet's nucleus. Comet
nuclei are themselves loose
collections of ice, dust and
small rocky particles, ranging
from a few kilometres to tens
of kilometres across.
Asteroids
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Asteroids, sometimes called
minor planets or planetoids, are
small Solar System bodies in orbit
around the Sun, especially in the
inner Solar System; they are
smaller than planets but larger
than meteoroids. The term
"asteroid" has historically been
applied primarily to bodies in the
inner Solar System since the outer
Solar System was poorly known
when it came into common usage.
The distinction between asteroids
and comets is made on visual
appearance: Comets show a
perceptible coma while asteroids
do not.
The End
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