US scientists announced the discovery of a new planet orbiting a star beyond the solar system, raising further hopes that life may one day be found elsewhere in the universe.

Scientists at NASA's Jet Propulsion Laboratory in Pasadena said a fifth planet had been found circling 55 Cancri, a star located 41 light years from Earth in the Cancer constellation.

Geoff Marcy, an astronomer at the University of California, Berkeley, said the discovery showed that other solar systems similar to the one in which Earth is located might be discovered in other reaches of outer space.

"This discovery of the first ever quintuple planetary system has me jumping out of my socks," Mr Marcy told a teleconference call.

"The significance is marvellous. We now know that our sun and its family of planets is not unusual.

"It shows that our Milky Way contains billions of planetary systems ... we strongly suspect that many of these planetary systems harbour Earth-like planets."