The Earth and Beyond

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The Earth and Beyond
The Solar System The Universe
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The Solar System - Our Sun
The SOLAR SYSTEM is the SUN and all of its
SATELLITES.
The Sun is a STAR. It gives out LIGHT and HEAT
due to NUCLEAR REACTIONS.
Our Sun is made up mainly of the elements
HYDROGEN and HELIUM, but not all stars are the
same. There are many different types with varying
SIZES, COLOURS and TEMPERATURES.
The satellites of the Sun all ORBIT the Sun
because of the Suns GRAVITY. The Sun is the MOST
MASSIVE object in the Solar System.
You should never LOOK at the Sun DIRECTLY as it
could damage your eyesight permanently!
There are many types of stars.
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The System of Sol
Pluto
Can you name them? (Not to scale!)
Uranus
Neptune
Jupiter
Saturn
Earth
Mars
Venus
Mercury
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The Planets
There are NINE planets in our Solar System. The
planets are kept in orbit by a combination of the
SUNS GRAVITY and their SPEED. The Earth takes
365.25 DAYS for one orbit of the Sun.
Unlike the Sun, the planets are seen by REFLECTED
LIGHT. They move around the Sun, not in circular
orbits, but in slightly squashed orbits
ELLIPTICAL ORBITS.
The first four planets, the INNER PLANETS, are
SMALL and ROCKY
The next four planets, the OUTER PLANETS, are
LARGE and GASEOUS
JUPITER
MERCURY
SATURN
VENUS
What about Pluto?
EARTH
URANUS
MARS
NEPTUNE
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The Planets
There are nine planets in the Solar System.
The planets orbit (orbit means to move around in
a path) the Sun in slightly elliptical orbits.
The planets are similar in some ways, but in
others are very different. By looking at
each of the planets in turn you can build up a
picture of the Solar System as a whole.
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Mercury
Relative mass 0.06
Diameter 4 879
Distance from Sun (million km) 57.9
Orbital period 88 days
Moons None
Mercury is the closest planet to the Sun. In
appearance and size Mercury is very similar to
the Moon. Mercury, like the Moon, has a cratered
appearance.
Mercury has an elliptical orbit and is the
second smallest planet after Pluto. During the
day the temperature on Mercury reaches
450Celsius. During the night, due to the lack of
atmosphere, the temperature falls to
180Celsius.
These harsh conditions mean that it is
unlikely there is life on Mercury.
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Venus
Relative mass 0.82
Diameter 12 104
Distance from Sun (million km) 108.2
Orbital period 224.7 days
Moons None
Venus is the second planet moving out from
the Sun. Venus is covered in thick clouds as seen
from Earth. We have been able to study the
surface of Venus using radar mapping.
Venus would not be a nice place to visit. It
has a surface temperature higher than that of
Mercury. This is caused by the Greenhouse
Effect of the dense Venusian atmosphere which
consists mainly of carbon dioxide.
If you stood on the surface of Venus you
would be incinerated by the high temperatures,
corroded by the sulfuric acid found in the
atmosphere, suffocated by the lack of oxygen and
crushed by the dense atmosphere.
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Earth
Relative mass 1
Diameter 12 756
Distance from Sun (million km) 149.6
Orbital period 365.3 days
Moons 1
The Earth is the third planet from the Sun.
It has a surface covered 70 by liquid water and
the rest by rock. It has an atmosphere that
consists mainly of nitrogen and oxygen. It is
also the only place in the Solar System where
life is known to exist.
The Earth spins once on its axis every 24
hours. This causes day and night on Earth.
The Earth is tilted on its axis. It is this
tilt that causes the Seasons.
It takes the Earth 365.3 days to orbit the
Sun once.
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Mars
Relative mass 0.11
Diameter 6 796
Distance from Sun (million km) 227.9
Orbital period 687.0 days
Moons 2
Mars is the fourth planet from the Sun. Like
Mercury, Venus and Earth, Mars is small and
rocky. Together these four planets make up the
four inner planets. Mars is often referred to as
the Red Planet. This is because it is covered
in red dust on the surface of the planet.
It was once thought that there was life on
Mars. Spacecraft have visited Mars but life has
not yet been detected. There is evidence liquid
water once flowed on Mars. Liquid water is a
requirement for life as we know it. Even though
there may be no life on Mars now, there may have
been life on Mars in the past.
Mars has two moons, Phobos and Deimos. They
are thought to be captured asteroids.
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Jupiter
Relative mass 318
Diameter 143 884
Distance from Sun (million km) 778.3
Orbital period 11.9 years
Moons 16
Jupiter is the largest planet in the Solar
System. If Jupiter had been eight times more
massive then it would not have formed a planet,
it would have formed a star.
Jupiter does not have a solid surface but is
a gaseous planet. Jupiter is famous for its Red
Spot this is a large storm in Jupiters upper
atmosphere that is three times bigger than Earth!
Jupiter has 16 moons. The four largest are
Io, Europa, Ganymede and Callisto. Europa is
thought to possess liquid water and it is
possible that it could support life.
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Saturn
Relative mass Relative mass 95
Diameter Diameter 120 536
Distance from Sun (million km) Distance from Sun (million km) 1 427.0
Orbital period Orbital period 29.5 years
Moons 8 major, several minor 8 major, several minor
Saturn is the sixth planet from the Sun and
is gaseous in nature. Saturn is famous for its
beautiful ring-system. The rings are not solid
but are thought to consist of millions of
particles of ice.
Saturn, like Jupiter, consists mainly of the
elements Hydrogen and Helium. Saturn has an
overall density that is less than the density of
water. This means that if you could find a sea
large enough, then the planet Saturn would float.
Will Hay, the famous British comedian, was a
keen amateur astronomer who discovered a White
Spot upon the surface of Saturn.
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Uranus
Relative mass 15
Diameter 50 724
Distance from Sun (million km) 2 869.6
Orbital period 84.0 years
Moons 15
Uranus is the seventh planet from the Sun
and is gaseous in nature. Uranus also has a
ring-system similar to Saturn. However, the rings
of Uranus are thought to consist of dust from the
break-up of a moon perhaps caused by an asteroid
collision.
Uranus is barely visible to the naked eye
and was unknown to ancient peoples. It is clearly
visible with a small telescope and has 15 moons.
Only five of the moons are visible from Earth
Miranda, Ariel, Umbriel, Titania and Oberon.
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Neptune
Relative mass Relative mass 17
Diameter Diameter 50 538
Distance from Sun (million km) Distance from Sun (million km) 4 496.7
Orbital period 164.8 years 164.8 years
Moons Moons 8
Neptune is the eighth planet from the Sun,
although for part of its orbit Neptune is the
furthest planet from the Sun. Neptune is the
fourth gas giant (along with Jupiter, Saturn and
Uranus).
Neptune has a ring-system and an active
cloud-system. The winds on Neptune are thought to
reach up to 2 000 kilometres per hour that is
faster than a bullet!
One of Neptunes eight moons, Triton, is
unusual. Triton is the only moon of a planet that
orbits in a direction opposite to the direction
of the planets rotation.
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Pluto
Relative mass Relative mass 0.01
Diameter Diameter 2 445
Distance from Sun (million km) Distance from Sun (million km) 5 900
Orbital period 247.7 years 247.7 years
Moons Moons 1
Pluto is the ninth planet from the Sun. It
was only discovered in 1930 by Clyde Tombaugh.
Indeed it was only in 1978 that it was discovered
that Pluto has a solitary moon. The moon of Pluto
is called Charon.
Pluto does not fit the pattern of planets in
the Solar System. It is thought to consist of
rock and ice. Pluto also has a very elliptical
orbit (which is why Neptune is sometimes the
furthest planet from the Sun). Some astronomers
do not think Pluto is a true planet and is more
similar to an asteroid or comet.
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Exercise 2 The Inner Solar System

1. Which two elements make up most of our local
   star?
2. Why should you never look directly at the Sun?
3. How many planets are small and rocky?
4. What do we call these small and rocky planets?
5. Which planet is closest to the Sun?
6. Which of these planets supports life?

Hydrogen and helium.
It could permanently damage your eyesight.
Four Mercury, Venus, Earth and Mars.
The inner planets.
Mercury.
Earth.
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Exercise 3 The Outer Solar System

1. Name the four outer planets.
2. Which is the largest of these four planets?
3. Name two differences between the inner planets
   and the outer planets?
4. Which outer planet has a spectacular ring system?
5. Which planet is furthest from the Sun for most of
   its orbit?

Jupiter, Saturn, Uranus and Neptune.
Jupiter.
The inner planets are smaller, rocky, have
shorter orbital times and are warmer than the
outer planets which are larger, gaseous, have
longer orbital times and are cooler.
Saturn.
Pluto.
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Exercise 5 Temperatures

1. Look at the table and graph. What pattern do you
   notice? What is the exception?

Planet Temp. (C)
Mercury 350
Venus 480
Earth 20
Mars -23
Jupiter -150
Saturn -180
Uranus -210
Neptune -220
Pluto -230
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Planet Temperatures
As you MOVE FURTHER AWAY FROM THE SUN, THE
TEMPERATURE OF THE PLANETS DECREASES. This is
because they receive less heat energy from the
Sun, the further away you get.
Some planets have an ATMOSPHERE. This can affect
the temperature of the planet.
This is why VENUS is HOTTER than MERCURY even
though Venus is FURTHER AWAY FROM THE SUN.
Venus has an atmosphere that contains GREENHOUSE
GASES, they let the Suns heat energy in, but
will not let it escape the planet gets warmer as
a result. The GREENHOUSE EFFECT. The surface of
Venus is hot enough to melt LEAD!
The surface of Venus is shrouded in thick cloud
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Exercise 6 Orbital Time

1. Use the data below to draw a graph showing how
   the orbital time of a planet varies with its
   distance from the Sun. What general pattern can
   you see?

Planet Solar Distance (Millions of km) Orbital time (Earth years)
Mercury 58 0.24
Venus 108 0.62
Earth 150 1.00
Mars 228 1.88
Jupiter 779 11.86
Saturn 1430 29.46
Uranus 2870 84.01
Neptune 4496 164.80
Pluto 5906 247.00
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Orbital Times
As you MOVE FURTHER AWAY FROM THE SUN, THE
ORBITAL TIME OF THE PLANETS INCREASES. This is
because the further away a planet is, the greater
the distance it must travel to complete one
orbit.
Remember, the planets orbits are ELLIPTICAL not
CIRCULAR.
An interesting point to note is that even though
we say that PLUTO is the planet that is FURTHEST
AWAY FROM THE SUN, this is not always TRUE. The
orbit of NEPTUNE is partly outside that of Pluto.
So, for part of its orbit, NEPTUNE IS THE PLANET
FURTHEST AWAY FROM THE SUN.
Neptunes orbit
Plutos orbit
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Moons
MOONS are the NATURAL SATELLITES of planets. The
natural satellite of the Earth is THE MOON.
Not all planets have moons. Some planets have one
or two, and some planets have lots.
Many moons have craters. Why?
Our moon is barren and lifeless. Some moons in
the Solar System are thought to hold the best
chance of finding LIFE even if it is in
primitive form.
EUROPA is a moon of JUPITER. Europa is thought to
possess LIQUID WATER underneath its icy surface.
Liquid water is a requirement for life as we know
it, so many scientists feel the BEST CHANCE of
finding life in our Solar System is on Europa.
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Comets
Comets are objects that orbit the Sun in
HIGHLY-ELLIPTICAL orbits. They are only seen for
a SHORT TIME when they are RELATIVELY CLOSE TO
THE SUN. Like Planets and moons, comets are seen
by REFLECTED LIGHT.
Comets are thought to consist of ICE and DUST
particles (like a dirty snowball). It was only
recently that we discovered the truth about
comets when several spacecraft flew close to
approaching comets one craft even passed through
the tail of a comet.
HALLEYS COMET is a famous comet that has an
orbital period of 76 YEARS. Very few people see
Halleys comet twice in their life and no one
ever sees it three times.
What is the tail of a comet?
Evaporating ice particles as the comet approaches
the Sun.
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Asteroids
Between the planets MARS and JUPITER thousands of
lumps of rock are found. These lumps or rock are
called ASTEROIDS. The region where they are found
is known as the ASTEROID BELT.
These asteroids have varying and eccentric
orbital paths. Some have passed very close to the
Earth in the past some have hit the Earth. Some
scientists believe that LARGE ASTEROIDS IMPACTING
on EARTH have resulted in MASS EXTINCTIONS in the
past.
There are several large IMPACT CRATERS on the
surface of the Earth thought to have been caused
by impacting craters.
The Moon has a lot more visible craters than the
Earth because the Moon has NO ATMOSPHERE to
protect it.
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Exercise 7 Moons, Comets and Asteroids

1. What do we call the natural satellites of
   planets?
2. Why can we only see comets for a short period of
   their orbit?
3. What makes up the tail of a comet?
4. Where is the asteroid belt found?
5. How do we see comets, moons and asteroids?

Moons.
They have highly-elliptical orbits, so for much
of their orbit they are in the outer Solar System
and too far away to see.
Evaporated ice particles as the comet approaches
the Sun.
Between Mars and Jupiter.
By reflected light.
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The Scale of Things
We live on a PLANET called EARTH.
The Earth and all the planets ORBIT the SUN.
Our Sun is one of many STARS.
MILLIONS OF STARS grouped together are called a
GALAXY.
Our Sun is part of a SPIRAL GALAXY called the
MILKY WAY.
There are MILLIONS OF GALAXIES, all the galaxies
together make up the UNIVERSE.
A spiral galaxy
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Exercise 8 Scale of the Universe
Our Sun is a _____. There are many different
types of star. _______ of star grouped together
are called a _______. Our local galaxy is the
Milky Way. The distances between the stars in a
galaxy are a lot bigger then the distances
between the ______ in our Solar System. There are
millions of galaxies together they make up the
________. The distances between galaxies in the
Universe is a lot bigger than the distances
between stars in a galaxy.
star
Millions
galaxy
planets
Universe
galaxy Universe planets star
millions
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Exercise 10 Match the Names with the Body
The Sun Europa Saturn The Milky Way
A moon A spiral galaxy A star A planet
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Exercise 9 Which
1. For the following bodies answer the questions
below.
Galaxy Saturn Asteroid Comet Sun North Star

1. Which are seen by reflected light?
2. Which are light sources?
3. Which are part of our Solar System?
4. Which two are stars?

Saturn, asteroid, comet
Galaxy, Sun, North Star
Saturn, asteroid, comet, Sun
Sun, North Star