For the universe, a bouncing baby planet

In earthly terms, it's as old as the hills but - in the stellar scheme of things - one million years is a mere babe in arms.

In earthly terms, it's as old as the hills but - in the stellar scheme of things - one million years is a mere babe in arms.

So when Nasa scientists announced yesterday they had found the youngest planet known to man, the new arrival was greeted with great excitement by stargazers. "It knocked our socks off," admitted Ed Churchwell, astronomer at the University of Wisconsin.

A telltale gap in the Taurus constellation, 420 light years from Earth, spied through Nasa's infrared Spitzer space telescope, was enough to prove the existence of a gaseous planet less than a million years old.

Compared to the youngest planets known before now, which are several billion years old - and the earth itself, which is thought to be more than 4.5 billion years old - it represented a planetary body in its infancy.

The Spitzer - launched last August as a £2bn replacement for the Hubble space telescope - saw the clearing while it was examining the disc-shaped dust cloud around a young star called Coku Tau 4.

Nasa described it as like the cleared trail left by a vacuum on a dirty carpet - proof that something more recent had passed through. Spitzer has also discovered two of the farthest planet forming discs yet observed, 13,700 light years away, which contain more than 300 new-born stars.

"By seeing what's behind the dust, Spitzer has shown us star and planet formation is a very active process in our galaxy,'' Dr Churchwell said. "It's kind of blown our minds and we are all excited by this, a new young planet."