But with so many options, how do we know which is best? You might think the most Earth-like planets should be top of our list. After all, we’ve got water, land, an atmosphere, and trillions of life forms lapping it all up.
But according to a small group of researchers, there are bigger and better planets out there. They’re called super-Earths.
Super-Earths may be some of the most common planets in our galaxy. Since 2009, the Kepler Space Telescope has discovered about 4,000 exoplanets. 30% of them are super-earths. And a few percent of those super-earths orbit within their host star’s habitable zone:
That’s a Goldilocks zone where the planet’s surface is just the right temperature for liquid water. Not too cold or too hot. Now, there’s a chance that some of these super-Earth’s aren’t rocky worlds like Earth. The larger ones could be made of mostly hydrogen and helium gas like Jupiter and Saturn which would not be hospitable for life.
But the reality is, astronomers are still gathering details as more data comes in. So, in the meantime, we’ll explore what life on a rocky, habitable super-Earth might be like.
Liquid water is just the start. These planets can be almost double Earth’s radius and up to 10 times more massive. And all that extra mass is what researchers think could really make super-Earths the perfect home. Because more massive planets have a stronger gravitational pull.
Super-Earth Kepler 20b, for example, is nearly double the size of Earth and is 10 times more massive. Making its surface gravity almost 3 times stronger. That stronger gravity means the planet can hold on to more air molecules forming a thicker atmosphere.
Which is great for protection against harmful space radiation. It also means mountains and hills would erode faster leaving a relatively flatter surface compared to Earth. Which might sound boring but scientists think this could actually spawn dozens of shallow islands across the planet.
Which, in turn, could be the perfect place for life to form and evolve. “Just as biodiversity in Earth’s oceans is richest in shallow waters near coastlines, such an ‘archipelago world’ might be enormously advantageous to life.”
There’s just one problem leaving this tropical paradise would be extremely difficult. The escape velocity on Kepler 20b is more than double compared to Earth’s. Which means either rockets would need more fuel to reach their destinations. For example, a mission similar to the Apollo moon landings would require twice the amount of fuel or, rockets could only carry a fraction of the payload.
For instance, SpaceX’s Falcon Heavy can launch 50,000 kilograms of payload into Earth’s orbit whereas it could only launch 40 kilograms into orbit around a super-Earth like Kepler 20b. That’s about the weight of a German Shepherd.
Suffice it to say, leaving a super-Earth would be a far greater challenge. But if it looked like this, would you really want to say goodbye? We’ll never know for sure until we visit one.