The most common “sized” world in the galaxy is a super-Earth, between 2 and 10 Earth masses, such as Kepler 452b, illustrated at right. But the illustration of this world as “Earth-like” in any way may be mistaken. (Credit: NASA/JPL-Caltech/T. Pyle)

Ask Ethan: Are ‘super-Earths’ really the most common planets in the Universe?

In terms of the planets we’ve discovered, super-Earths are by far the most common. What does that mean for the Universe?

When it comes to the question of what’s out there in the Universe, it’s vital to remember that what we see isn’t necessarily what we get. In astronomy, as in any observational science, you’re only going to see what your instruments and tools are capable of detecting, and you’re going to detect greater numbers of the objects you’re most sensitive to. Since 1990, humanity has leapt from only knowing of the planets within our Solar System to nearly 5000 confirmed exoplanets, with another 4000+ planetary candidates from Kepler, K2, and TESS awaiting confirmation.

In a surprising find, the most abundant type of planet discovered so far is neither a gas giant nor a rocky planet, but rather a new class of planet in between the two: best known as super-Earths. But are super-Earths really the most common type of planet in the Universe, or is this simply a way that our current data and capabilities are fooling us? That’s what Victor Taveras asks, wanting to know just how ubiquitous super-Earths really are:

“I see it said that Super Earths are the most common planets we have…