CHAPTER 2: THE UNIVERSE
this chapter, we will dwell on the planets and other bodies
in the universe. The Sun, Moon and Earth are among the ones
we are most familiar with. There are, however, other celestial
bodies in the universe you are not able to see.
Think about cartoon films or movies about
space! The space above the clouds is full of stars, planets
and meteorites that you have seen in these films. Each one
of these is called a celestial body. Billions of these celestial
bodies come together to form the giant collection of star
systems we call galaxies. All celestial objects are enormous.
For instance, our planet Earth is really quite small in comparison
with the other celestial bodies. Despite this, it is big enough
to hold human beings, animals, mountains, oceans and everything
else you can think of.
Now let us proceed to the giant collection
of star systems, the galaxies where billions of stars exist
Galaxies are composed of billions of stars.
(Stars are big celestial bodies such as the Sun. Neither the
Earth nor the Moon is a star.) There are about three trillion
stars in the biggest galaxy. In a galaxy of an average size,
there are about 200 to 300 billion stars, while there are
about 100 billion stars in a small galaxy.
Now let's stop and think for a moment:
What does the number one billion mean to you? For example,
if you put two zeros next to the number one, it becomes 100.
If you add one more zero to this number, it becomes 1,000.
Add another zero and now you have the number 10,000 (ten thousand).
Can you count up to 10,000? Maybe you can, but this will probably
take a long time. Meanwhile, we still have not reached a billion.
Then let us add two more zeros to 10,000. Now we have 1,000,000
(one million). We are still short of the number of stars in
galaxies. However, if you put three more zeros next to 1,000,000,
you reach the number 1,000,000,000 (one billion). Can you
count up to 1,000,000,000? Let's answer this outright: Counting
up to one billion would take a few decades, a decade being
a period of ten years.
we have almost reached the number of stars in galaxies. If
you put two more zeros next to the number 1,000,000,000, it
becomes 100,000,000,000 (one hundred billion). This is the
number of stars in the smallest galaxies.
Now do you have some idea of the size
of the universe? If you spent all your life doing nothing
but counting numbers, you would still fail to count all the
stars in space. Allah, the Creator of the universe, has created
this vast space that you are unable to imagine from nothing,
and He encompasses every point of this immense universe every
moment. Allah knows and sees every being in our giant universe,
and everything that happens. The infinite power of our Lord
is related in the Qur'an as follows:
... He knows what is in the heavens and
what is on earth. Allah has power over all things. (Surah
Al 'Imran: 29)
Now let's return to our topic and try
to learn more about the galaxies.
In galaxies of average or large size,
there exists a galactic centre. Around the galactic centre
are arms rotating at immense speed. These arms are made up
of stars, gas and dust clouds.
With their arms and centres, galaxies
are the biggest celestial bodies in space. These giant celestial
bodies also form clusters of celestial bodies. There are thousands
of galaxies in some galactic clusters. Moreover, these galactic
clusters form other clusters of celestial bodies. This regular
clustering goes on and on, getting bigger and bigger.
Now let's go over what we have seen so
- Galaxies are composed of billions, even
trillions of stars.
- The big and average galaxies have galactic
The galaxy has arms made up of stars, gas and dust clouds.
These arms spin around the galactic centre at great speed.
- The galaxies come together to form galactic
clusters. Sometimes, there may be thousands of galaxies inside
a galactic cluster. The galactic clusters also come together
in clusters of clusters.
Keep in mind that a galaxy composed of
100 billion stars is a small galaxy, not to mention that every
star is at least as big as the Sun. In addition, there are
both large and small planets such as our Earth that spin around
many of these stars.
Now, consider the following: Could billions
of stars gather together by chance in an orderly manner? Could
the stars spontaneously establish an order in which they can
move without colliding with other celestial bodies (for instance
our Earth and other planets)?
These are all unlikely. This means that
the stars' spinning and moving at great speed without colliding
with other celestial bodies since the first day of their existence
is a sign of the existence of a Creator, a Planner and an
Organiser, Allah, the Ruler of the universe. Allah has created
countless paths for the planets, stars and comets in space.
All these celestial bodies follow their own paths without
colliding with one another.
Now let's continue our journey with our
The Milky Way
The Milky Way is the name of the galaxy
in which our Earth is located. The Milky Way galaxy is enormous.
As is the case with all big galaxies, the Milky Way also has
a galactic centre. You will probably remember what a galactic
centre is since we discussed it in the previous section. The
stars inside these centres are older stars; they are red or
yellow in colour. The stars in the arms of the galaxies are
mostly young and hot stars of blue colour. These aside, gas
and dust clouds exist in these arms.
arrow shows the location of our Earth in the Milky Way.
The Milky Way has the shape of a spiral;
in fact, the shape of the galaxy is identical to a "pinwheel".
That is, it has arms at the centre extending towards the outer
parts. There are four arms. One of these is the "Hunter Arm".
The group of planets called the "Solar System" is located
in this arm, and our Earth is one of the planets within this
Our Solar System is located a little more
than one half of the way out from the centre of this spiral-shaped
galaxy. The Sun (and our solar system) is revolving around
the centre of the galaxy, and makes a complete revolution
every 220 million years or so.
The giant Milky Way has maintained this
form and movement for billions of years. Although the stars
in it revolve at great speed, they preserve their own paths.
However, it is not possible for stars
to form such patterns on their own. It is also impossible
for them to reach agreement; that is to line up in the most
appropriate way and to move in an organised manner. Nor is
it possible for the laws that govern these stars to have formed
by themselves. Think about the stones in your garden! Could
these stones take a decision and say, "Let some of us form
the centre and the rest take up positions on the arms, and
then perpetually spin in the garden"? Would you believe someone
who says he had heard the stones talking to each other in
this way? No doubt, you would not. By the same token, saying
that the Milky Way came into existence by coincidence and
the stars started to move of their own accord would be as
funny as the example of stones in the garden. Keep in mind
that celestial bodies are non-living, unconscious beings just
like the stones in the garden.
No power other than Allah is capable of
creating billions of giant stars in an orderly universe. Allah
created them and the laws to which they are subject. They
all testify to His power and control over the entire universe.
For that reason, each piece of information we learn about
the universe reminds us of Allah's existence and His creation
of it. This way, Allah also shows us His infinite wisdom and
Now, let us proceed to the stars.
Stars and planets come into existence
through the compression of the masses of gases and dust in
space called "nebulae". For this reason, nebulae, the sources
of celestial bodies, have a major role in the universe. Nebulae
do not have any light of their own as is in the case of stars.
Therefore, it is hard to see them. They become visible only
when their inner gas gives off light or if they reflect the
light coming from stars. We can also see them when they pass
by a source of light.
Looking from a distance, we
see stars as pentagons or hexagons. Actually, stars
are round, just like our Sun.
Stars give off heat, light and energy.
Apart from tiny stars, there are also very large stars. Surprisingly
the Sun is not a major star as we believe to be; There are
many stars much bigger than it.
Well, did you know that stars also have
life spans? Stars are not living beings, but just like them,
they are born, lead a life and die.
As we have shown, stars come into existence
in the nebulae. A huge star's life often ends in an immense
explosion, the material that makes it up being scattered in
every direction. From these scattered pieces, there emerge
the elements that contribute to the construction of relatively
smaller stars and planets. The Sun and planets within the
Solar System and our Earth have come into being following
the explosion of a huge star in the past.
Now, let's take a tour in our Solar System
and see how it looks!
THE SOLAR SYSTEM
our Solar System, there are nine major planets with 61 satellites
and countless asteroids, all revolving around a single star
called the "Sun". The Sun is located at the heart of the Solar
These nine planets, which are a part of
our Solar System, revolve around themselves as well as the
Sun in an orderly pattern. Let us review the names of the
planets starting from the one closest to the Sun: Mercury,
Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
As you can see, our Earth is the third planet
from the Sun.
Every planet within the Solar System has
different features. The temperatures on some of these planets
are high enough to cause lead to melt. Others, on the other
hand, are totally covered with ice. Some of the planets are
entirely composed of gases. Moreover,
some planets are as tiny as the Moon.
is a very harmonious relationship between the satellites and
their primaries. (In astronomy, a primary is something that
another body revolves about. Earth's primary is the Sun; the
Moon's primary is Earth.) Planets attract their satellites.
However, satellites balance this attraction. Without such
a balance, satellites would become stuck to the planets or
break loose into space.
For instance, if the Moon rotated slower,
it would plunge into Earth at an immense speed. This would
mean the end of Earth. If it rotated faster, it would gradually
move away from Earth and would no longer be our satellite.
Now let's look at the Sun, the heart of
our Solar System.
The Sun is the greatest celestial body
in the Solar System. It consists of very hot, glowing gases.
Every second, explosions occur all over its surface, for the
Sun itself is an enormous nuclear bomb. These surface explosions
are equivalent to the energy given off by millions of atom
bombs. They shoot off flares 40-50 times larger than our Earth.
The Sun looks like a ball of fire and
gives off enormous heat and light from its surface. If the
Sun did not exist, it would always be night for us, and our
whole world would be covered with ice. Most importantly, there
would be no life on Earth.
The surface temperature on the Sun is 6,000°C (11,000°F),
while its internal temperature is 12,000,000°C (21,600,000°F).
Space (you will also remember the films
about the space) is a very dark, huge, empty place. Our Earth
is a celestial body in this dark expanse, and no other celestial
body is near enough to illuminate and heat our Earth.
The light from the Sun is very bright.
You have probably tried looking at the Sun on a clear day.
After looking for a few seconds, your eyes were dazzled, weren't
they? Because its light is very bright, looking straight at
the Sun is very dangerous for our eyes. As well as that, being
exposed to sunlight for a long time in summer is dangerous.
Severe sun-burns may occur on our skin, and they only heal
up after medical treatment. Especially in summer, the heat
radiating from the Sun is very high. However, the Sun is millions
of kilometres away from Earth, and only one part in two-thousand
of the heat it radiates reaches Earth.
the temperature of Earth is so high despite the distance between
Earth and the Sun, can you imagine how hot the Sun is?
Scientists provide approximate values
for this. However, we cannot have any idea of this temperature
by trying to compare it with the temperature of anything we
are familiar with in this world. Consider that on the surface
of the Sun, the temperature is 6,000°C (11,000°F). Inside,
it rises as high as 12,000,000°C (21,600,000°F). There is
nothing as hot on Earth with which you could compare this
temperature! Your hands can hardly touch water around 50°C
(120°F). Even on hot summer days, the temperature remains
at about 40-50°C (105-120°F). This example shows that Allah
tuned the distance between Earth and the Sun most delicately.
If the Sun were a little closer to us, everything on the world
would be withered and dried by the heat and turn into ashes.
However, if it were a little more distant, everything would
freeze. Of course, life would not be possible in either case.
If our Sun were closer to Earth,
our planet would become overheated. All of these delicate
balances are under Allah's control.
Polar regions, where heat from the Sun
is received less, are always covered with ice. The equator,
on the other hand, the region where many more solar rays are
received, is always hot. Allah has created these regions as
examples for us. Other regions are more suitable to support
life for human beings. This shows the mercy Allah pours down
on us. That is because, if Allah had not tuned the distance
between the Sun and Earth so delicately, life on Earth would
be much harder for us. There might even be no life at all.
As we have explained earlier, Allah created
the Sun and the Moon exactly the way it has to be for human
life to exist on our planet. In the Qur'an, Allah informs
us that the Sun and the Moon move by the command of Allah:
Allah is He Who raised up the heavens without
any support-you can see that-and then established Himself
firmly on the Throne. He made the sun and moon subservient,
each running for a specified term. He directs the whole affair.
He makes the Signs clear so that hopefully you will be certain
about the meeting with your Lord. (Surat ar-Ra'd: 2)
The Gravitational Attraction of the
Countless celestial bodies move in an
orderly manner without colliding with one another because
Allah placed them in finely-adjusted orbits. An orbit is the
path a planet or comet follows as it revolves around the Sun.
No planet stops following its orbit to fly off into the depths
of outer space. That is because planets remain under the gravitational
attraction of the Sun. As you read these lines, our Earth
is moving at the enormous speed of 108,000 kilometres (70,000
miles) per hour in its orbit around the Sun. An analogy may
help you to grasp the enormity of this speed: the maximum
speed a car can travel is around 200 kilometres (125 miles)
per hour. This means the speed of Earth's rotation around
the Sun is 540 times the speed of a car. Another example is
the following: a bullet moves at a speed of 1,800 kilometres
(1,100 miles) per hour. The speed of Earth's rotation around
the Sun is 60 times the speed of a bullet.
The delicate balances created
by Allah, and His Control over everything, allow us
to walk and run on this planet without difficulty.
Because of this high speed the Earth moves
at, the gravitational pull of the Sun is very important. If
the Sun started to exert less gravitational force, we would
fly off into space together with the Earth. This would certainly
be the end of Earth…
On the other hand, if the Sun started
to exert an even greater gravitational force, then our Earth
would plunge into the Sun and melt. In this case, we would
also vanish. Furthermore, the gravitational pull of the Sun
also prevents the planets in their respective orbits from
colliding with each other. However, have you ever thought
how the Sun attracts these planets?
The answer is obvious. It is our Creator
Allah, Exalted in Power, Who creates and continually preserves
Besides, not only the Sun has a gravitational
pull. The planets within the Solar System also have their
own gravitational forces. For instance, the gravitational
force of Earth attracts the Moon towards it. Because of this
gravitation, the Moon is almost suspended at a certain distance.
In this way, Earth does not collide with the Moon. Without
doubt, the infinite might of Allah prevents the Moon from
falling onto Earth.
There is another gravitational pull similar
to that of the sun, which is specially designed for mankind
to live. That is the gravitational pull of the earth that
gives us our weight. The gravitational force, which we experience
as weight, holds us on Earth and provides us with the ability
to walk and run with ease without floating off into space.
Assume that there is a ball in your hand.
What happens when you withdraw your hand? The ball drops,
doesn't it? That is because gravity attracts it to the ground.
However, if you left this ball far out in remote outer space,
the ball would not fall down since there is less gravitation
there. Therefore, the existence of the higher force of gravity
on Earth is essential for us.
There is another very important detail
about gravitation: Gravitation should be neither more nor
less than its current force. If it were less, you would be
walking up in the air and not be able to touch the floor with
your feet. You would not be able to move as you wish; you
would constantly drift from one place to another, bounce when
you take a step and hit the ceiling. Similarly, if the gravitational
force of Earth were greater, you would not be able to walk
because you would be drawn down towards the ground. You would
only be able to crawl along the ground, if that.
Yet, none of these happen to us; Allah
has created exactly the right strength of gravitation for
You can attain a better understanding
of this by help of an example: The Moon, like Earth, also
has a gravitational force. However, this gravitational pull
is less than the one on Earth. Therefore, it is not possible
for you to survive on the Moon. On television, you have probably
seen how astronauts walk on the Moon. Could we spend our entire
life this way? Definitely not.
Now let us continue our journey by visiting
the planets within the gravitational pull of the sun.
We mentioned earlier that planets are
the celestial bodies that rotate around the stars. In this
section, we are going to examine the planets in the solar
system our Earth is located in. If we assume the Solar System
to be a circle, the Sun is right at the centre of it.
is the planet on the outermost circle. Pluto is the smallest
and farthest planet from the sun. Observation of this planet
is hard, and even the Hubble telescope can only show some
rough details of its surface. This planet is quite a cold
place. The temperature is around -238°C (-396°F). In winter,
when the temperature on Earth dips below-2or-3°C (-28 or -26°F),
it becomes freezing. -238°C (-396°F) is a temperature 100
times colder than a temperature we on Earth can hardly resist
in wintertime. This kind of cold would end our lives. From
the outside, Pluto looks like a ball covered in ice.
closer towards the sun, we meet Neptune. This planet is also
quite "cold"; its surface temperature is about -218°C (-360°F).
Its atmosphere consists of gases poisonous to human beings.
This aside, dreadful storms reaching up to 2,000 kilometres
(1,250 miles) per hour blow over its surface.
a little further towards the sun, in the middle of the circle,
we meet Uranus. Uranus is the third largest planet in the
Solar System. The temperature of its atmosphere is about -214°C
(-353°F), which means this planet is cold enough to freeze
us in only a second. Its atmosphere consists of poisonous
gases that definitely would not support life.
we continue our journey towards the sun, we next encounter
Saturn. This, the second largest planet of the Solar System,
is particularly notable for the system of rings around it.
These rings are made up of gases, rocks and ice. The temperature
on this planet is again unsuitable for human life: -178°C
we come even closer to the sun, we encounter Jupiter, the
largest planet of the Solar System. Jupiter is a planet 11
times bigger than Earth. Conditions on this planet are again
not suitable for life, and it is a very cold place.
Jupiter comes Mars. Mars is a dead planet that does not even
compare to Earth. Mars has no life on it. There are reasons
for this: First, the atmosphere of Mars is a poisonous mixture
containing concentrated carbon dioxide. Second, there is no
water on the planet. Third, the temperature on Mars is about
-53°C (-63°F). Finally, there are very strong winds and sandstorms
on Mars that last for months.
blue planet that appears before us after Mars is our Earth.
We will focus our attention on our planet Earth in the last
chapter. Meanwhile, let's remind you of one point: Our Earth
is the only planet that allows organisms to live.
towards the sun, our search brings us to a planet called Venus.
Venus is the brightest celestial body after the Sun and Moon.
Therefore, people have known it since ancient times. Although
all the planets as far out as Saturn have also been quite
familiar to people throughout the ages, Venus is incomparably
bright and clear in both the morning and evening skies. In
contrast to the other planets, Venus is very hot. The temperature
on the surface is 450°C (840°F), which is enough to cause
even lead to melt. Another feature of Venus is its heavy atmosphere
composed of a concentrated layer of carbon dioxide. Besides
that, the atmosphere of Venus contains layers of acid several
kilometres deep. No organism could survive in such a place
for a second.
away from Venus, we reach Mercury, the planet closest to the
sun. Its rotation has been
so slowed down by its proximity to the Sun that the planet
makes only three full turns in the time it takes to revolve
twice around the sun. That is why one side of Mercury is extremely
hot while the other is extremely cold. The difference between
the day and night sides of Mercury is as much as 1,000°C (1,800°F).
Of course such an environment cannot support life.
Our search so far reveals that except
for Earth, none of the planets in the Solar System offers
anything that might serve as a haven for life. Each of them
is a lifeless and silent body. Our world, however, is a planet
that provides everything necessary for life. With its green
forests and blue oceans, it looks beautiful from space. The
first astronauts on the Moon were astonished by the colourful
and bright view they had of Earth.
OTHER CELESTIAL BODIES
Some other celestial bodies in the Solar
System are comets, asteroids and meteorites. These are the
celestial bodies remaining from the nebula in which the Solar
System originated four to six billion years ago.
- Comets are made up of condensed gases
and dust. Sometimes, their orbits bring them closer to the
sun. As the comet approaches the sun, its surface starts evaporating
because of the heat. This evaporation causes a bright light.
A huge ball of gas and dust appears around the nucleus. This
ball of gas and dust is called a "coma". Also, there is a
tail of gas and dust related to this coma.
Meteorites are meteors that reach the Earth's surface.
- Meteors are rocky objects in space.
Usually, they are observed in between the orbits of Mars and
Jupiter. In some cases, the diameter of meteors may be as
much as 1,000 kilometres (620 miles).
- Meteorites are solid bodies which fall
to Earth from outer space. Pieces of rock, or mixtures of
rock and iron detach themselves from meteors and comets. Sometimes
when Earth passes through the dust cloud remaining from a
comet, for example, the objects within this dust cloud burn
in the atmosphere. They heat up when they enter Earth's atmosphere
and leave a fine line of light in the sky. This is called
a meteor. Sometimes, when they do not burn completely, meteors
strike the Earth. These meteors that reach Earth are called
aerolites or meteorites.
Consider one important point here: Meteors
that reach the atmosphere occasionally fall on the Earth.
When they fall, the destruction they cause varies according
to their size. Our Earth is vulnerable to such a threat at
every moment, but our Lord has created these celestial bodies
in such a way that they are usually burned and destroyed in
the atmosphere and thus are no danger to us. This shows Allah's
mercy and compassion for us as well as the protection He provides
You must now have grasped that Allah has
control over all celestial bodies, whether huge or small,
and governs them all at every moment in a planned and orderly