JULIE PRICE

Last week it was a pregnant man; this week it's another parent-child relationship, but of a different kind. For one small group of scientists at the School of Physics & Astronomy at St Andrews University, it was a particularly momentous occasion: the birth of a planet.

The group of astronomers this week released the first image of a protoplanet still embedded in its birth material, which the team leader, Dr Jane Greaves, compared to the first cells that make up a human embryo in the womb, the difference being the baby is a planet, and the parent a star. The planet is called HL Tau b after its parent HL Tau.

The team discovered HL Tau b while studying the parent star, around 520 light years away in the constellation of Taurus. HL Tau's unusually massive and bright surrounding disc of gas and rocky particles make it an excellent place to search for signs of forming planets. The parent star is thought to be less than 100,000 years old - extremely young compared with the Sun, which is 4600 million years old. The embryo planet is estimated to be as little as a few hundred years old, which makes it the youngest planet to be documented. Scientists expect it to take millions of years to turn into a massive planet, similar to Jupiter.

Since the planet is still in its early stages of formation, it provides scientists with a unique opportunity to scrutinise how planets take shape. Dr Greaves said that, thanks to the discovery, scientists should be less "narrow-minded" about the possibility of finding other Earth-like planets in the universe.

Of course, the team at St Andrews is carrying on a tradition that stretches back to William Herschel, who discovered Uranus in 1781. He spotted it through his telescope from his back garden in Bath. The existence of Neptune was later predicted using mathematical arguments based on Newton's law of gravitation by two men, John Couch Adams in England and Urbain Le Verrier in France (it was later spotted by a German astronomer, Johann Galle in 1846). Pluto is the most recent planet to be discovered. It was found in 1930 by an American Clyde Tombaugh.

Having acquired a fair amount of knowledge of our own galaxy (and come up with strong theories that there is no life on Mars, the most Earth-like planet within our solar system), scientists have directed their quest for extraterrestrial life towards planets outside our solar system. The first extrasolar planet was discovered in the early 1990s.

The birth of new planets, such as HL Tau b, suggest that the universe is still expanding and poses the question: are other planets being born in distant galaxies that could - like Earth - have the right conditions to support life?

A recent project known as The Big Bang supports the theory that the universe is always expanding. Scientists hope an atom-smashing machine called the Large Hadron Collider (LHC) will allow them to replicate the beginning of the universe. The atom-smasher is due to be switched on in Switzerland in a few months.

However, the project has been criticised recently by scientists who believe it could pose a threat to Earth. Walter Wagner, who runs a botanical garden on Hawaii's Big Island along with a Spaniard, Luis Sancho, have filed a lawsuit claiming that the machine poses at least a small chance of annihilation of our planet and, maybe, the universe. Meanwhile, back in St Andrews, the small team of university astronomers is quietly looking out from Earth to other planets - future planets - and stumbling upon new ways of discovering what is out there.