What is a star? Stars are huge celestial bodies in space, consisting of hydrogen and helium. Because hydrogen burns constantly in them, they shine very brightly.
Some stars have planets that orbit around them. Our earth is such a planet and our star is called the sun.
While the Sun shines very brightly for us, the other stars in space are only small, faint lights in the night sky.
There are so many stars in space that you can’t even count them.
All stars except the sun are so far away that we cannot reach them even with our best rockets. The light takes eight minutes from the sun to the earth.
The star that is closest to us after the sun is called Proxima Centauri.
The light needs from there to us already more than 4 years. With other stars, this can be thousands, millions or billions of years.
The science that deals with stars is called astronomy.
The name comes from the Greek word for star. Astronomers use their telescopes to observe other celestial bodies such as planets and comets.
There are small telescopes to look through and huge telescopes that do this automatically. Astronomers then try to understand all the information.
What happens on the stars?
The energy needed for a star to shine is produced when hydrogen becomes helium. Stars are glowing hot.
They can be blue, yellow, orange or red. Stars are many millions of years old. They are formed from clouds of gas in space that condense into a star.
If all the hydrogen is converted into helium, the star changes. Large stars can then explode and become a white dwarf, a neutron star or a black hole. Small stars shrink again and become colder and colder and shine more and more faintly.
How many stars can you see in the sky?
Not everything that we see in the night sky as a bright spot is also a star.
Because they are so far away, we also see whole star clusters as a single point of light. Such star clusters are also called galaxies.
We can also see planets as luminous points. In contrast to stars, planets do not shine themselves. They shine only because the light of our sun falls on them.
When visibility is good, you can also see a bright band in the sky: the Milky Way.
It consists of a particularly large number of stars because they belong to our galaxy. In the Milky Way, there are about 100 billion other stars in addition to our sun.
There are countless numbers of such galaxies and each of them contains millions to trillions of stars.
How many stars you can see with the naked eye depends on how dark it is and how clean the air is.
In cities there is a lot of light from street lamps, cars and houses and the air is full of exhaust fumes.
In deserts or on high mountains you can see 3,000 to 6,000 stars.
With telescopes and cameras, you can see stars that are even further away and even fainter.
Why can stars be useful to humans?
People have always looked at the sky and tried to explain what they see.
In the ancient Greeks, for example, someone said that stars are made of fire.
Some stars seem to be closer together. When you connect them with lines, you seem to see things. This is how constellations began to be seen.
In the past, many people believed that the stars were made by the gods.
In addition, one could read the future from the stars. Or the stars influence life on earth.
However, this is not true, the stars are much too far away to change anything on earth. It is different with the sun.
It provides us with light and heat, day and night and the seasons.
But the stars were important early on to find our way on earth. This was the only way for sailors to orient themselves on the sea.
If you look at the sky at night from the earth, the stars seem to be firmly fixed in the sky. That is why they are called fixed stars.
If you observe them for a whole night, you think: All stars move together across the sky. In reality, the earth rotates beneath them.
Seen from the earth, the stars rotate in the north and in the south, each around a certain point, the so-called “celestial poles”.
In the northern hemisphere, there happens to be a clearly visible star, the North Star. So if you have found this star, you know where north is.
Which stars you can see also depends on the season. So the stars helped when the first calendars were made.
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