About the Universe and its mysteries


At the time of the night when you are peeping into the sky. At that time you are not only seeing the stars, moons, and darkness of the sky. But you are also seeing the limitless and endless and fabulous depth of the universe. The planets, the galaxies, and the stars stretch into space, which is just beyond our imagination. So let’s start this fabulous and amazing journey of the universe. In this journey of the universe, we are going to discuss and explore more and more about the universe as much as possible. You also come across some unknown facts that will amaze you in wonder.

Definition about the universe

The universe is defined as the ‘whole of existence‘. It includes everything that exists, everything that has existed, and everything that will exist. It may be all of space, matter, energy, and time. Now let’s understand the universe first. In ancient times people thought that the universe was a giant spare. But we know that it is not that easy. We only have theories or assumptions about it. No one knows or can say exactly about it. Some probabilities are that the universe has no center or outer age. Only some fraction of the universe is visible to us which is also known as the observable universe. The whole universe may be much bigger than the observable one.

Origin of universe

Many theories are there for the origin of the universe. But the best supported or accepted theory is the theory of the Big Bang. The main concept behind the theory of the big bang is the discovery that the neighboring galaxies are moving away from us. And also these galaxies are moving at an accelerating speed. The theory of the big bang says that the universe materialized out of nothing. And the reason for that expansion is unknown. The universe expands from an atom-sized particle to trillion kilometers just in a fraction of a second. At the earlier stage of expansion, the universe is too hot for the formation of particles. Then it cools down slowly and after that the matter formation takes place.

The shape of the universe

It is somewhat technical to understand the shape of the universe but according to scientists, the three dimensions of space are bent by the force of gravity. This force of gravity is due to the matter in the universe which exists in the fourth dimension. And that matter is not visible to us, not even with the help of electromagnetic radiation. This is really hard to understand or visualize so to make it easy to understand the scientist uses the metaphor of a two-dimensional rubber sheet. This rubber sheet can be bent into three shapes: closed, open, and flat. The shape of the rubber sheet depends upon the packing of the universe with the matter. Let’s discuss how the matter density of the universe and its shape are interrelated.

Shape of universe
Credit: NASA & WMAP


If the universe is dense it would bend itself into a closed shape. And also if you traveled in a straight line it would bring you back to the place from where you started moving.


If the universe is not dense enough then there is a possibility that it might be stretched into an open space. In this shape, the universe is infinite in size and it does not contain any outer edges.


This shape is only possible with the right amount of matter density in the universe. In this type of shape, the size of the universe is assumed to be infinite and it does not contain any outer edges.

What is the universe made of?

What is the universe made of?
Two views from Hubble of the massive galaxy cluster Cl 0024+17 (ZwCl 0024+1652) are shown. To the left is the view in visible light with odd-looking blue arcs appearing among the yellowish galaxies. These are the magnified and distorted images of galaxies located far behind the cluster. Their light is bent and amplified by the immense gravity of the cluster in a process called gravitational lensing. To the right, a blue shading has been added to indicate the location of an invisible material called dark matter that is mathematically required to account for the nature and placement of the gravitationally lensed galaxies that are seen. Credits: NASA, ESA, M.J. Jee and H. Ford (Johns Hopkins University)

98% of the normal and observable matter that we can see is made up of helium and hydrogen. And 2% is made up of other elements. But if we see the broad picture of what the universe is made up of? then we come to know that it contains dark matter, dark energy, and normal or visible matter. And the percentage of these elements in the universe is dark energy occupying nearly 68% and dark matter occupying nearly 27% and visible matter or normal matter occupies only 5% of the total space of the universe. Let us discuss them briefly below.

Dark energy or dark matter

According to scientific researches and observations, the universe is expanding constantly at an increasing or accelerating speed. So there must be some driving force or energy behind it. No one can exactly define this phenomenon of the expansion of the universe at an accelerating speed. No one has the correct explanation about it. But the scientist or theorists give a name to the solution. The name of the solution or reason behind the expansion of the universe is dark energy.

Dark energy

There are still many things that we have to explore in the case of the universe. There is not much information we have about dark energy. What we can do is estimate how much dark energy must be present in the universe. The estimation is done on the basis of its effect on the expansion of the universe or on the rate of expansion of the universe. Many theories and explanations are given to explain dark energy but none of them succeeded to explain all of its perspectives and applications. It is still a mystery what dark energy actually is?. This question still has to find its answer.

Dark matter

Some observations state that the visible or normal matter is not sufficient enough to explain the phenomenon in this space. So there comes the idea of dark matter. Simply it is made up of such particles having properties like that they do not observe, reflect or emit light. So that’s why we cannot detect them simply by observing electromagnetic radiation. We also can’t see them directly. But we know that it exists somewhere in space because we can see its effect in space.

The scale of space

As we already discussed, the universe is so vast that we can’t even imagine. That’s why scaling the universe is practically not possible. So what we can do is just we can make an estimate about its size with a relative method. We don’t have the measurement of the whole universe. But we have the measurement of space in terms of the light-year up to some limit. So let’s start from a small scale to a large one. But before that let us discuss some facts. In space, we are going to deal with very vast space and the km aren’t big enough. So we can’t measure the distances in space with the help of kilometers that we are used to on the surface of the earth. So in the case of space, we generally use the light-year as a unit of distance.

We know that the speed of light is 3 x 10^8 m/s. A light-year is a distance covered by light in any year. So one light-year is equal to approximately 10 trillion kilometers or 6 trillion miles. To make it more simple, let us take an example: if you run within the speed of light then you can travel around Earth 7.5 times in a second. Like you start from one point of the earth travels in a straight line and reach to that same point of the earth 7 times in a second. This is really amazing.

Let’s start a journey from Earth to the universe.

Earth and moon

If we talk about how wide the earth is then its distance comes out to be 12756 km. Our nearest neighbor is the moon. The moon orbits Earth at a distance of 384400 kilometers. If we compare the size of the Earth and the moon then if the earth is compared to the size of football then the moon will be the size of a melon.

Solar system

We know the solar family consists of one sun and eight planets in our solar system. This solar system covers a region of 9 billion km. Let’s take an example to understand it better. If the earth is compared to the size of football then it would take 5 days to travel or walk across the solar system. And it would take 58 years to walk if you want to reach the nearest star to the sun.

Solar system
Source: NASA/JPL
Published: February 18, 2009

Stellar neighborhood

The nearest star to the Sun of our solar system is Proxima Centauri. And this Proxima Centauri is 4 light-years away from the Sun. And it’s amazing to know that this Stellar neighborhood is just a tiny fraction of our Milky way galaxy.

Milky way galaxy

You will be amazed to know that the Milky Way galaxy is just a vast cloud of 200 billion stars. And the shape of the Milky way galaxy resembles a pair of fried eggs held back to back. Which has a central bulge surrounded by a flat disc. And if we talk about the measurement across the disk of the galaxy then it comes out to be 100000 light-years. And it is 2,000 light-years if we measure it through the bulge.

Local groups of galaxies

There are many many galaxies in our observable universe. And our Milky Way galaxy is just one of them. The galaxies exist in a group called clusters. And they are held together by the force of gravity. And our Milky Way galaxy is the part of the cluster that is known as the local group. The approximate width of the local group is about 10 million light-years.


The supercluster is just a term given to the larger groups of clusters of galaxies. The supercluster in which our galaxy exists is known as the Virgo supercluster. Virgo supercluster is one of the billions of superclusters in the known universe. Between the superclusters, there is an immense empty area. Also, this empty area is known as the cosmic void.

The known universe

Superclusters are supposed to form a vast web of elements riddled with enormous voids containing no galaxies in them. In simple words, it resembles a web-like structure. As we already discussed, no one knows exactly about the shape and size of the universe. So the true shape and size of the universe is still a mystery. What we know or what is visible to us is just a fraction of the universe. The universe may be infinite in size with no edges.

Celestial bodies

Most of the universe’s space is empty. In fact, at least 99.9% of the universe is empty. So the universe is full of dark voids and is very vast. Astronomers named the objects that keep flowing from here and there in space as celestial bodies. They can be dust if planets, stars, and galaxies. Our solar system consists of planets, moons, and the sun. All of them originated from the same cloud of gas. As per the studies of the early 20th century, our solar system is not the only one in the universe. Our solar system is just one of the billions that exist in our galaxy. Now let’s discuss these celestial bodies one by one.


Asteroid in solar system
Source: NASA
Published: July 12, 2018
Bennu and other asteroids represent building blocks of our solar system’s rocky planets

They are the rocky lump that was leftover at the time of the formation of the solar system. Their size varies from a typical rock to bodies close to the size of a draft planet.


They are simply a chunk of ice. And they generally belong to the outer reaches of the solar system. Some of them grow a long tail of dust and gas. The reason behind the formation is the heat the sun got from the sun while approaching it.


Moon is also known as the natural satellite. This is simply the body that revolves around the planet. Every planet has different numbers of moons. Earth has one moon while Jupiter has nearly 67.

Draft planet

Their size lies between the asteroid and the planet. They are bigger than the asteroids but smaller than the planets. Like planets, they are also round in shape. The best example of the draft planet is Pluto.


Planets are large in size and nearly spherical in shape. They orbit the star in a definite path or in their orbit. In our solar system, we have eight numbers of planets.


Stars are luminous balls of gases. The science by generating their own nuclear power. They usually greatly vary in types, temperatures, and sizes.


In space, there are growing clouds of gases and dust, usually known as Nebula. Some of them are created by dying stars which release clouds of wreckage. And others give birth to new stars.


In this article, we took a small tour of the Universe. We still have to explore the universe a lot. Many things are still unknown to us. We are getting more and more information about space and the universe by the time. But we still have to solve many mysteries. In this article, we have discussed the universe, its origin, matter, and shape. We have also discussed the scaling of the universe. Most of the space of the universe is empty and the remaining one is filled with celestial bodies. We also discussed these celestial bodies in short. According to researchers, the universe is expanding at an accelerating speed. And no one knows when this expansion will stop. We don’t even know the exact reason, force, or energy behind this expansion. Let’s hope future research will uncover all the secrets of the universe.


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