Most of the stars visible from Earth are in the Milky Way, our galaxy. The galaxy gets its name from its appearance. There is a “milky” glow to the band of stars above the Earth. This is caused by the brightness and distance of the stars combined with the atmosphere of the Earth which you have to look through to see the stars.
What it is
The Milky Way is a spiral galaxy that contains the sun and the planets of the solar system, as well as billions of other stars, gas, dust and other cosmic matter. The stars have been organised into many different groups called constellations. These are “star patterns” as seen from Earth, although in reality, stars that are parts of constellations are often vast distances apart and independent of other stars in the same constellations.
According to astrophysicists Eric Christian and Samar Safi-Harb of NASA, the Milky Way galaxy is about 1,000 light years thick and approximately 100,000 light years in diameter. The speed of light is 299,792,458 metres per second. Therefore, if you could travel at nearly 300,000 metres per second, it would still take you 100,000 years to get from one end of the Milky Way to the other.
The Milky Way is billions of years old. Even NASA is not entirely sure quite how old the Milky Way is, but it could be 13.5 billion years old. Some of the stars in the inner halo are 11.5 billion years old. This shows that the stars of the Milky Way formed over very long time periods. The Milky Way has been in the sky much longer than human beings have been on planet Earth.
The most important star in the Milky Way to Earthlings is the Sun. This is about 150 million km away from Earth. The Sun makes it possible for life to exist on Earth by keeping the temperature reasonably stable and providing energy for living things in the form of heat and light. Other stars in the Milky Way are likely to be similar to the Sun in some ways but further scientific study is necessary to determine their precise characteristics.
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