what are stars?
In the night sky, stars look like tiny points of light far away in the distance. Some stars look bigger and brighter than other ones. If you watch closely and for a long time, you might notice that most stars seem to move through the sky over night. Depending on where you live, you might see some stars only at certain times of year. Other stars might show up all year round, but in different parts of the sky. Some stars, you might never see where you live. What is going on with stars, anyway?
The Sun and Stars
Stars have a lot in common with the sun. In fact, the sun is a star. One way you can think of the sun is as a huge, constantly burning fire. If you’ve ever stood near a fire or hot stove, then you know how you can feel the heat coming from it. The larger the fire, the hotter it feels and the brighter it is when you stand close to it. When you’re too close, you can get burned badly (and it’s easy to feel when you’re too close). When you stand far away from a really big fire, you can still feel heat coming from it. If you turn around, you can feel the heat on different parts of your body.
The sun is huge...
The Sun is like a fire that is big enough to fit our entire world plus 960,000 copies inside. That’s a lot of Earths. And a fire that big creates A LOT of heat. The sun is about 5,504 degrees Celsius, or 9,939 degrees Fahrenheit. Think about how hot it is when the temperature is 100 degrees outside, then multiply that by 100. That’s the kind of heat you would feel if you could stand next to the Sun.
...but far away
Luckily, we are not that close to the Sun. We are about 150 million kilometers, or 93 million miles, away from the Sun. Any closer, and Earth would be much too hot for us to live on. Any farther away, and Earth would be much too cold. We are at just the right distance.
Since we are so far away from the Sun, it actually takes about 8 minutes for the Sun’s light to reach us. That means that it takes 8 minutes from the time the Sun sends out a wave of energy to the time that wave reaches Earth. Of course, the Sun is constantly sending out waves of energy, like the heat from a fire. Or if someone switches a flashlight on and off really fast. That is why we always see light during the day.
Stars are even farther away
The next closest star to us is called Proxima Centauri. It is more than several billion kilometers and miles away. At that distance, it takes about 4 years for its light to reach Earth. That means if Proxima Centauri was a flashlight, it would take 4 years from when someone switched it on to when we would see the light.
Like the Sun, Proxima Centauri constantly sends out waves of energy. When we see it, we actually see light it sent out 4 years ago. Looking at the stars is a little bit like looking back in time.
Because it is so far away, Proxima Centauri looks like a tiny spot in the night sky. When its light finally gets here, we see it as only a small spot in the night sky. If we could travel all the way out to Proxima Centauri and look back, our Sun would look like a small spot too.
Like the Sun, Proxima Centauri constantly sends out waves of energy. When we see it, we actually see light it sent out 4 years ago. Looking at the stars is a little bit like looking back in time.
Because it is so far away, Proxima Centauri looks like a tiny spot in the night sky. When its light finally gets here, we see it as only a small spot in the night sky. If we could travel all the way out to Proxima Centauri and look back, our Sun would look like a small spot too.