Welcome to the family! Scientists using NASA’s Kepler spacecraft have confirmed at least eight new roughly Earth-sized planets sitting in the habitable zones of their host stars -- two of which rival the most ‘Earth-like’ planets found to date.

The two most Earth-like planets, known as Kepler-438b and Kepler-442b, both orbit red dwarf stars that are smaller and cooler than the Sun, researchers said.

This means they are “promising candidates” for potential life form.

Lead scientist Dr Guillermo Torres, from the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts, said: “Most of these planets have a good chance of being rocky, like Earth.”

With a diameter just 12 per cent bigger than Earth, Kepler-438b has a 70 per cent chance of being rocky, the scientists have calculated. Kepler-442b is about one-third larger than Earth, and the likelihood of it being rocky is around 60 per cent.

The eight discoveries are just the latest in a series of exoplanets found by the spacecraft. Since launching in 2009, Kepler has found 1,004 confirmed planets along with 4,175 planet candidates.

Image: An artist’s impression of an Earth-like planet orbiting a star near the end of its life surrounded by a shell of expanding gas. The two most Earth-like planets discovered – Kepler-438b and Kepler-442b – orbit red dwarf stars that are smaller and cooler than the Sun.