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The Alpha Centauri system is about 4.2 light years away. So, if you had a spaceship that travelled at the speed of light, it would take 4.2 years to get there (and another 4.2 years to get back!). 4 billion kilometres only gets you from Earth to Neptune. An astronomical unit (AU) is the average distance between Earth and the Sun so 4 AU from Earth gets you about to Jupiter. One parsec is equal to 3.26 light years so 4 parsecs overshoots our nearest star.

True. Neutron stars so squished that their atoms all merge together into one gigantic blob of neutrons. You can imagine a neutron star as the universe’s biggest atom – the size of a small city, but as heavy as the whole solar system!

Sirius is the brightest star in the whole sky and is visible in the Southern Hemisphere in the constellation Canis Major, which is near Orion. Alpha Centauri is the brighter of the pointer stars that point at the Southern Cross. It’s the third-brightest star in the sky, and it’s actually two stars orbiting each other. Actually, it’s three stars, but the third, Proxima Centauri, is so far from the other two that it appears as its own star in the sky.

In about 5 billion years, the Sun will start to run out of hydrogen for fuel and will expand hugely, becoming a red giant star. In the process, it will engulf Mercury and Venus and probably the Earth, too. At this point it will start using helium as fuel. Later, the hot core of the Sun will shrink and turn into a white dwarf star. The Sun is not big enough to become a black hole.

The word pentagram comes from Ancient Greek. Penta- means five and -gram means drawing. A pentagram can be drawn with five straight lines, without lifting your pencil. A hexagram is a six-sided star. A pentagon is a five-sided shape. A rhombus is a four-sided shape whose sides are all equal.