Light from distant galaxies contains the fingerprints of the elements those galaxies contain.

When we analyse that light, we see something unexpected. The fingerprints are not in their usual place; they seem to be shifted towards the red end of the spectrum.

The effect is known as redshift – and we can explain it if the galaxies are moving away from us.

Have you ever noticed how the sound of a passing ambulance siren changes?

As the ambulance passes, the note gets lower. It’s because the sound wave from the receding ambulance is stretched.

Now imagine a slightly different scenario. You and the ambulance are both stationary, but the road between you is growing longer.

The effects of this unlikely event are much the same as when the ambulance drove by. The ambulance moves farther away, and sound waves from its siren are stretched.

The universe behaves like the expanding road. As distant galaxies move away from us, their light is stretched like the sound waves from the retreating ambulance.

Stretched light waves have longer wavelengths. They become redder. In fact, every ray of light that crosses the universe is shifted towards the red end of the spectrum.

The effects of an expanding universe increase with distance. The farther the galaxy, the more space its light has to cross – and the greater is the stretching effect.

Are women better suited to space travel?

America’s first astronauts were known as the Mercury Seven. They were all men.

NASA also tested 13 women for the Mercury project. Most of them scored higher than the men, and all of them were passed fit for space duty. They are now known as the Mercury 13.

The tests showed that the women were less likely than the men to suffer from heart attacks, loneliness, cold, heat, pain, and noise. They needed less oxygen, and they weighed less, which made them cheaper to send into orbit.

In July 1961, NASA cancelled all further testing of women. New regulations required astronauts to have experience of flying jet-planes – something which the US military did not allow women to do.

The first woman on the Mercury project was Jerri Cobb. In tests, she scored higher than all the men, including John Glenn.

Jerri is still campaigning for her space flight. NASA have confirmed that there will be a place on the Shuttle for her…if they continue their research on ageing and space.

The space toilet looks more like a vacuum cleaner than a toilet.

And that’s roughly how it works. Urine and faeces would float around the cabin if the space toilet didn’t use a gentle flow of air to pull it in the right direction!

This Russian space toilet is a prototype for those used on the Mir space station. Astronauts urinate into the yellow funnel and defecate into the hole.

The toilet has a detachable canister for solid waste. When full, the canister is removed, sealed, and jettisoned through an exit hatch.

The canister burns up as it re-enters the atmosphere – so there’s no chance of being hit on the head by a bucket of excrement!

Space stations recycle urine for astronauts to drink and breathe!

Urine from the yellow funnel flows down a pipe to another container. The urine is treated with acid for four days, then filtered. The filtered urine is turned into steam which later condenses into water. It’s now ready for drinking again…and again…and again.

Passing an electric current through the recycled water splits it into hydrogen and oxygen gas. The hydrogen is vented into space, and the oxygen is circulated round the space station.

Toilets on the Space Shuttle are slightly different. They have a proper seat and look more like a conventional toilet. Shuttle missions are short, so waste can be stored until the spacecraft returns to Earth.

Shuttle astronauts urinate into a hose that has different adaptors for men and women.