This artist’s animation begins by highlighting the newest member of the 55 Cancri family, a massive planet, likely made of gas, water and rock, about 45 times the mass of Earth and orbiting the star every 260 days. This planet is the fourth out from the star, and lies in the system’s habitable zone (green). A habitable zone is the place around a star where liquid water would persist. Though the newest planet probably has a thick gaseous envelope, astronomers speculate that it could have one or more moons. In our own solar system, moons are common, so it seems likely that they also orbit planets in other solar systems. If such moons do exist, and if they are as large as Mars or Earth, astronomers speculate that they would retain atmospheres and surface liquid water that might make interesting environments for the development of life.
The animation ends with a comparison between 55 Cancri and our solar system. The colors of the illustrated planets were chosen to resemble those of our own solar system. Astronomers do not know what the planets look like.
The Kepler 11 system includes 6 (or more) planets that are larger than Earth and smaller than Neptune, all very close to their host star. The composition of these planets is unknown, but they must be amazing environments!
Today more results from the Kepler spacecraft were announced. 68 earth sized (rocky iron) planet candidates were announced. 54 planet candidates were found in the habitable zone of their star. Most of these are gas giants, that may host one or more moons with liquid water. Keep in mind that Kepler is looking at 140 000 stars, and can only detect planets that pass between their host star and us (maybe a thousandth of all planets in view) The spacecraft has been looking for 22 months, so many planets with periods longer than 2 years have not been detected. One solar system found has 6 planets orbiting closer than Venus in our own solar system, most of these planets are of an unknown type, between super-earths and tiny Neptunes. All this from a tiny tiny fraction of the 100 billion stars in our galaxy.
It’s really big. You should try it sometime. Start with something small, like 100 oranges. Visualize them in your minds eye, and multiply. Soon you have to look down on yourself from space to even see them all.