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INTERNATIONAL YEAR OF ASTRONOMY
To mark the end of the event in Britain, astronomers chose to celebrate 5000 years of star watching at Stonehenge – the prehistoric stone circle southern England, whose exact relationship with the heavens is still being unravelled. Our reporter Tracey Logan was there to find out what the IYA has achieved, and also why ancient astronomical monuments like Stonehenge are a window onto the lives of our ancestors.

METEORITE HUNTING
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Although not many meteorites are seen hitting the ground and most fall into the sea, thousands are found each year. Meteorites can be found all over the world, but are easiest to spot in dry places, such as deserts such as the one in Arizona in the US, which is where reporter Pauline Newman went with meteorite hunters Ruben Garcia and Laurence Garvie.

Scientists known as cosmochemists are able to work out what has happened throughout the life of a meteorite by studying its chemical structure, revealing a little piece of the solar system's history one rocky chunk at a time.

ALZHEIMER'S DISEASE AND AGEING
The older you get, the more likely you are to get the neurological disease Alzheimer's. But is the ageing process actually causing the disease?
Professor Andrew Dillin from the Salk Institute for Biological Studies in California, used some mice that are genetically programmed to live for a long time to find out.

PAPER BATTERIES
By printing special carbon nano-tube ink onto ordinary paper. Researcher Liangbing Hu at Stanford University can make paper batteries.

SEAHORSES
At a young age, marine biologist and avid diver Helen Scales became fascinated by the beauty of seahorses. She talks to Jon Stewart about her passion and her new book Poseidon's Steed: The Story of Seahorses, From Myth to Reality (Gotham). The book chronicles her decade-long journey to find the seahorse, both in history and in its native watery depths.