The amazing Kepler Space Telescope has now catalogued over 1,000 exoplanets. Among them are eight new planets located within habitable zones, including two that astronomers say are the most Earth-like planets yet. Here's what we know about Kepler-438b and Kepler-442b.


Illustration: David A. Aguilar (CfA)

Prior to yesterday's announcement by scientists at the Harvard-Smithsonian Center for Astrophysicists, the most Earth-like planets were Kepler-186f and Kepler-62f. Respectively, they are 1.1- and 1.4-times the size of Earth, and receive 32% and 41% as much light.

The two new planets, which may be terrestrial, both orbit red dwarf stars that are smaller and cooler than our Sun. They're both in the so-called Goldilocks Zone, which means they receive enough sunlight such that liquid water can remain stable on the surface — an important prerequisite for life.


Kepler-438b takes 35 days to revolve around its host star and it has a diameter just 12% larger than Earth. There's a 70% chance that it's terrestrial. This exoplanet receives about 40% more light than Earth, and has a 70% chance of being in the habitable zone. For comparison, Venus gets twice as much solar radiation as we do here on Earth. It's located 470 light-years away.

Kepler-442b features an orbit of 112 days and has a diameter that's about one-third larger than Earth. It has a 60% chance of being rocky. This exoplanet receives about two-thirds as much light as Earth, and has a 97% chance of being in the Goldilocks Zone. It's located 1,100 light-years from Earth.

Unfortunately, the vast distances involved will make it difficult to make more precise observations, but I suspect that over time, and with more sophisticated telescopy, we'll learn more about these promising potentially habitable candidates.


You can find out more here.