Whenever you observe the sky, you see millions of stars. with a telescope you can see many million more. these beautiful stars, along with many other things we cannot see, make up our universe. no one knows how big the universe is, how it came into being. today, many scientists believe that about 16 billion years ago, there was an unbelievably large explosion called the "Big Bang'.
Our Universe us made up of the debris that was left over from this huge explosion. Many of these millions of points of light in the night sky are suns like our own Sun, except that they are often much bigger. These other suns may well have their own planets, but we cannot see them. Even with the most powerful telescope, a star never becomes more than a blurry, twinkling point of light.
Our imagination cannot grasp the vast distances that makeup the Universe. it is nt good trying to measure these distances in killometers becasue there are so many zeros involved that the whole exercise becomes confusing and meaningless. In order to make measuring distances in space easier, scientists use a unit of measurement called light-years. This is the distance light will travel in a year (about 9 000 000 000 000 or 9 trillion killometers). The distance from Earth to the nearest sar is 3.5 light-years. No one on Earth can reach it; eveb a spacecraft travelling at 50 000 killometers/hour (km/h) would take many thousands of years to reach the nearest star. And some stars are millions of light-years away.
Many stars are grouped together in nebulae, or clusters. Theree are millions of stars in a nebula. Many of them are shaped like gigantic spirals. Although they can be seen from Earth only through powerful telescopes, we can see the nebula to which our Solar System belongs. Nebula are shaped like lenses. We call it Milky way or Galaxy and it can be seen at night as a broad band of light across the sky. When we look at the Milky way we are looking length ways through the middle of the mass of stars.
Our Universe us made up of the debris that was left over from this huge explosion. Many of these millions of points of light in the night sky are suns like our own Sun, except that they are often much bigger. These other suns may well have their own planets, but we cannot see them. Even with the most powerful telescope, a star never becomes more than a blurry, twinkling point of light.
Our imagination cannot grasp the vast distances that makeup the Universe. it is nt good trying to measure these distances in killometers becasue there are so many zeros involved that the whole exercise becomes confusing and meaningless. In order to make measuring distances in space easier, scientists use a unit of measurement called light-years. This is the distance light will travel in a year (about 9 000 000 000 000 or 9 trillion killometers). The distance from Earth to the nearest sar is 3.5 light-years. No one on Earth can reach it; eveb a spacecraft travelling at 50 000 killometers/hour (km/h) would take many thousands of years to reach the nearest star. And some stars are millions of light-years away.
Many stars are grouped together in nebulae, or clusters. Theree are millions of stars in a nebula. Many of them are shaped like gigantic spirals. Although they can be seen from Earth only through powerful telescopes, we can see the nebula to which our Solar System belongs. Nebula are shaped like lenses. We call it Milky way or Galaxy and it can be seen at night as a broad band of light across the sky. When we look at the Milky way we are looking length ways through the middle of the mass of stars.