Unlocking the Secrets of Stars
Stars are giant balls of hot gas so far away that no scientist has ever gone near one — yet just by looking at a star's color, they can tell exactly how hot it is.
What Are Stars?
Stars are giant balls of hot gas that shine. They make their own light and heat. Our Sun is a star, and it is the closest one to us. Stars look small because they are so far away.
Star Facts
- Colors: Stars come in different colors, like red, blue, and yellow. The color tells us how hot they are. Blue stars are the hottest, and red stars are cooler.
- Constellations: Stars form patterns in the sky called constellations. You can see shapes like the Big Dipper or Orion.
- Twinkling: Stars twinkle because their light has to travel through Earth's atmosphere, which is a little bit wobbly.
How Do We Study Stars?
Scientists use special tools to study stars, like telescopes. Telescopes help us see stars that are far away. They also study the light from stars to learn what they are made of.
- Telescopes: Big and small, telescopes help us see further.
- Spectroscopes: These tools break starlight into colors, like a rainbow, to help us learn what stars are made of.
Notice how much a scientist can work out without going anywhere near a star. The color alone tells them how hot it is, and splitting that color apart tells them what it is made of.
An astronomer looks at a star and sees that it is blue rather than red. What has she just found out about it?
- That it is hotter than a red star
- That it is bigger than a red star
- That it is closer to Earth than a red star
Next time you look up at a star, remember: the twinkle you see is happening in the air above your head, not in the star itself. And its color is already telling you exactly how hot it is.