You probably know of a few famous examples. Copernicus showed that Earth and the other observable planets move around the sun, not the sun around Earth. Galileo showed that the moon is covered with enormous craggy peaks and rugged valleys. Astronomers from all over have shown that our sun, our life-giving star, is not any big deal; it’s one among billions. Even our galaxy is hardly unusual. Billions of those, too.

Image Bill Nye Credit... Jesse DeFlorio

Just imagine finding a planet with a comfortable surface temperature and an atmosphere with substantial amounts of not only water vapor, but also methane, the main component of natural gas. Although, nominally, there is more than one way to produce it, the main way we get new natural gas and organic molecules is by the natural processes of organisms. We’re talking about microbes, either the ones inhabiting seas and swamps, or those that live inside creatures like us.

So where do we look if we want to find microbes? Better yet, how do we look? Finding a planet not too different from our own would be a logical place to start. What sets Earth apart from all the other planets that we know well — Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune — is its distance from the sun, which enables it to have liquid water. It has a suitable atmospheric pressure and surface temperatures between liquid water’s freezing and boiling points, 0 to 100 degrees Celsius (or 32 to 212 in those quaint “Fahrenheit” degrees).

The scientists who found the Trappist-1 system were searching for just that, and they found not one, but seven exoplanets — planets not in our solar system — orbiting the star. Three seem well suited to having liquid water on their surfaces.

In the coming months and years, astronomers will refine the search, hoping to tease out the critical spectral data that would tell us whether there is water vapor in these remote atmospheres, as well as liquid water in an ocean.