Nasa 'Earth-like' planet discovery: What is the Kepler Space Telescope and when will the announcement be made?

The internet has suddenly lit up over news that Nasa may be about to announce a huge discovery. Here we go through what you need to know.

What’s going on?

Nasa will unveil the discovery of a new planet reportedly similar in atmosphere and substance to that of Earth – i.e. capable of supporting life.

Why are people talking about something called Kepler?

The Kepler Telescope, launched by Nasa in 2009, has one purpose: to find Earth-like planets orbiting other stars. If Nasa has found a new Earth, this is the mission that will have discovered it.

It surveys portions of the planet's Milky Way, monitoring the brightness of aproximately 145,000 sequence stars. The observatory beams the images back to scientists in Nasa who then examine the images to see if the brightness has dimmed as exoplanets cross in front of the stars. Costing a relatively cheap (for space missions) $400 million, Kepler is part of Nasa Discovery programme.

So far, the telescope has found 1,000 alien planets – but none that come nearly close enough to the conditions found on our own planet.

When will we find out?

The space agency is live streaming a conference from 5pm where scientists, will announce their findings to the world. You can watch the live stream here, as well as follow our live coverage here.

Why is this a big deal?

"Exoplanets, especially small Earth-size worlds, belonged within the realm of science fiction just 21 years ago," a Nasa statement said, doing nothing to calm the semi-feverish wonderings on much of the internet.

"Today, and thousands of discoveries later, astronomers are on the cusp of finding something people have dreamed about for thousands of years – another Earth."

Space watchers are speculating that because Nasa is holding a live press conference – rather than just releasing the data in a press release or report – they may have made their most significant discovery to date.