Cuts that draw blood go deeper than your top-skin. Just below are cells like the ones in the picture. They keep fairly busy making a protein called keratin that helps to protect your skin. Eventually these cells lose their DNA and end up squashed flat forming the protective top-skin.

A supernova (soop-er-no-va) happens when a star blows up in the sky. This can release enough energy to outshine an entire galaxy of billions of stars. The fiery image of Simeus 147 was captured by telescopes pointed towards Taurus. The light from this cosmic catastrophe reached the Earth about 100 000 years ago.

An embryo is a tiny-ball of cells. As cells grow and multiply, a miracle of organization unfolds and body-shapes begin to emerge in the form of a foetus. The picture shows an embryo from a ribbon-worm at the very beginning of its development, the two-cell stage. Ribbon-worms have long delicate tape-like bodies and live on beaches all over the world.

The star in the picture will soon explode. Soon for astronomers could still be another million years, so don’t hold your breath. This one is around 100 times as heavy as our Sun. It has used up all of its fuel but is still millions of times brighter than the Sun. It has started to fume a bit and is shooting big balloons of stuff out.

Crane flies look like giant mosquitos. In the UK we call them daddy long-legs. In the USA they are called jimmy spinners or mosquito eaters, but they rarely eat mosquitos. There are 14 000 different species making them one of the largest insect groups. They feed on nectar or not at all. Most live only to mate and die as adults.

A nebula is a dust cloud filled with hydrogen and charged particles of gas. A planetary nebula forms when a star dies, but stars can be born from such dust clouds too. The picture shows a nebula that is rectangular in shape. Astronomers believe this is a cylinder viewed from the side, an unusual nebula that marks the death of a star.

A lady called Henrietta Lacks died about sixty years ago from cancer. Some of her cells were kept by the hospital for research. These were called ‘HeLa’ (Hee-La) cells after her. They divide to make new cells at a furious rate and are easy to culture in the laboratory. The cell in the picture is about to split into two.

When stars get old they don’t always die quietly. Some create the most wonderful fireworks displays called supernovas. Kepler spotted this exploded star without even using a telescope because the bang caused it to glow so bright in the sky. The explosion sent gas and dust flying into the surrounding space at millions of miles an hour.

The lung in the picture isn’t just swollen with air as it should be. It is filled with many tiny lumps. Doctors call the condition sarcoidosis (sour-coy-dough-sis). Some people don’t even notice they have it, but others can die. Most will have some trouble breathing and the lumps can spread to other organs. No one knows what causes the problem.

The planet Saturn is a giant ball of gas. The huge rings around it are made up from smashed comets and other rubbish floating in space. Storms on Saturn are violent and can last for many years. The picture shown was taken by the Cassini spacecraft. This storm is larger than planet Earth and faster than any hurricane we’ve ever seen.