THE BIG BROTHER PLANETS ; Earth’s New Family

ASTRONOMERS have discovered two planets they have branded Earth’s big brothers.

The planets beyond our solar system are 10 to 20 times the size of Earth – but are far smaller than any previously detected.

And experts in the US said they make up a new class of Neptune- sized ‘extrasolar’ planets.

The findings suggest they were formed through accumulation of rocky bodies – just like Earth.

Over the past decade, as many as 135 planets have been found but all of them are giant gas planets.

Co-discoverer, Dr Geof-frey Marcy, of the University of California, said: ‘We can’t quite see the Earth-like planets yet, but we’re seeing their big brothers.’

Experts used ‘radial velocity’ in which a planet’s gravitational tug is detected by the wobble it produces in the parent star.