Scientists may have found the first water worlds

There are two planets that may not be what we thought they were. It was thought that the planets were larger than Earth. Data shows that the planets are not as dense as we thought. The only realistic way to get densities like that is for a lot of their volume to be occupied by water or a similar fluid.

We have bodies like this in our Solar System, most notably the moonEuropa, which has a rocky core surrounded by a watery shell. The new planets are closer to their star than a vast ocean and a steam filled atmosphere would be.

Let’s revisit that

There are two main ways to find an alien planet. One can watch for dips in the light from their star caused by planets that are in an elliptical pattern around the star. The second is to know if the star's light occasionally shifts to red or blue due to the pull of planets.

Whether or not a planet is present can be determined by either method. A lot of information about the planet is given by having both. We can estimate the size of the planet by looking at the amount of light blocked by it. The star's light can be red and blue. We can see its density with both of those. High density means rocky with a metal-rich core and low density means rich in gas.

We were able to do that at the Kepler-137 system. The data showed that the system has three planets. It looks like a small rocky body. The rocky planets that were larger than Earth were called super-earths. All of them were very close to the red dwarf star, with the most distant being 0.25 astronomical units away.

There wasn't anything unusual about this system that would require a second look. It made sense for researchers to study the planet's atmospheres. As the planet transits in front of its host star, a small amount of light will pass through the atmosphere on its way to Earth. The atmosphere will allow us to see their presence.

The team of researchers obtained the data from the two space telescopes at the right time. Things got weird when that happened.