Is it habitable?

“Just right” is more likely to be somewhere in between.

For a planet, the habitable zone is the distance from a star that allows liquid water to persist on its surface – as long as that planet has a suitable atmosphere.

In our solar system, the planet Earth sits comfortably inside the Sun’s habitable zone. Broiling planet Venus is within the inner edge, while refrigerated Mars is near the outer boundary.

In the Milky way, there are more planets than galaxies, often referred to as an exoplanet, is any planet beyond our solar system. Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center, and are untethered to any star.

Determine the distance of an exoplanet from the star itself, as well as the star’s size and energy output, and you can estimate whether the planet falls within the habitable zone.

We live and are surrounded in a universe of exoplanets. The count of confirmed planets is in the thousands and rising. That is from only a small sampling of the galaxy. The count could rise to the tens of thousands within a decade, as we increase the number, and observing power, of robotic telescopes lofted into space.

Image credit: NASA