The Stars

Key facts

Sirius

Sirius, the “Dog Star”, is the brightest star in the night sky. It shines so brightly because it is both powerful (about 25 times brighter than the Sun) and close. It has a tiny companion: a white dwarf called Sirius B.

Polaris

Polaris is the North Star. It isn’t the brightest star, but it’s special: Earth’s axis points almost straight at it, so while all other stars circle through the night, Polaris stays put. For centuries it guided sailors and travellers.

Betelgeuse

Betelgeuse is a red supergiant in Orion’s shoulder. If it replaced our Sun, it would swallow Mercury, Venus, Earth and Mars. It is near the end of its life and will one day explode as a supernova.

Rigel

Rigel is a blue supergiant marking Orion’s foot. It is much hotter than our Sun and pours out tens of thousands of times more light. Blue supergiants live fast and die young.

Vega

Vega is one of the brightest stars in the sky and part of the “Summer Triangle”. It spins so fast that it bulges at its equator. Astronomers used it as the standard for measuring how bright other stars are.

Proxima Centauri

Proxima Centauri is the closest star to the Sun. It is a small, cool red dwarf – too faint to see without a telescope. It belongs to the Alpha Centauri triple-star system.

Quiz

1. What does a star’s colour tell you?

   • ☐ Its age
   • ☐ Its temperature
   • ☐ Its distance
   • ☐ Its name

2. Why does Polaris seem to stay still all night?

   • ☐ It’s very close
   • ☐ It’s almost straight above Earth’s North Pole
   • ☐ It doesn’t shine
   • ☐ It moves with the Moon

3. Which is the closest star to the Sun?

   • ☐ Sirius
   • ☐ Vega
   • ☐ Proxima Centauri
   • ☐ Polaris

Find it in the sky

Use the Sky Finder at seethestar.com. Tick what you find and write when you saw it.