NASA added 1,284 new planets to the known galaxy on Tuesday, more than doubling the number of confirmed planets orbiting alien stars, in what it said was the biggest single announcement of new exoplanets.

Of the 1,284 discovered, nearly 550 could be rocky planets like Earth, based on their size, according to NASA.

For four years, the Kepler space telescope monitored 150,000 stars in a single patch of sky, measuring the tiny, telltale dip in the brightness of a star that can be produced by a transiting planet.

Source: Mirror