NASA’s Kepler telescope has found ten more planets outside our solar system of probably the size and temperature to support life – a new total of 49.

Kepler’s Mario Perez said: ‘We are probably not alone.’

Seven of the 10 newly found Earth-size planets circle stars that are just like ours, not cool dwarf ones that require a planet be quite close to its star for the right temperature.

That does not mean the planets have life, but some of the most basic requirements that life needs are there, upping the chances for life.

‘Are we alone? Maybe Kepler today has told us indirectly, although we need confirmation, that we are probably not alone,’ Kepler scientist Mario Perez said in a news conference.

Outside scientists agreed that this is a boost in the hope for life elsewhere.

C2DWHW NASA's Kepler spacecraft
NASA’s Kepler spacecraft

‘It implies that Earth-size planets in the habitable zone around sun-like stars are not rare,’ Harvard astronomer Avi Loeb, who was not part of the work, said in an email.

The 10 Goldilocks planets are part of 219 new candidate planets that Nasa announced as part of the final batch of planets discovered in the main mission since the telescope was launched in 2009.

It was designed to survey part of the galaxy to see how frequent planets are and how frequent Earth-size and potentially habitable planets are.

Kepler’s main mission ended in 2013 after the failure of two of its four wheels that control its orientation in space.

It is too early to know how common potentially habitable planets are in the galaxy because there are lots of factors to consider including that Kepler could only see planets that move between the telescope vision and its star, said Kepler research scientist Susan Mullally of the SETI Institute in Mountain View, California.

It will take about a year for the Kepler team to come up with a number of habitable planet frequency, she said.

Kepler has spotted more than 4,000 planet candidates and confirmed more than half of those.

A dozen of the planets that seem to be in the potentially habitable zone circle Earth-like stars, not cooler red dwarfs.

Circling sun-like stars make the planets ‘even more interesting and important’, said Alan Boss, an astronomer at the Carnegie Institution, who was not part of the Kepler team.

One of those planets – KOI7711 – is the closest analogue to Earth astronomers have seen in terms of size and the energy it gets from its star, which dictates temperatures.

Before Kepler was launched, astronomers had hoped that the frequency of Earth-like planets would be about one percent of the stars.

The talk among scientists at a Kepler conference in California this weekend is that it is closer to 60%, he said.