The Kepler spacecraft has been finding planets all over the place during its K2 mission. To date, it has found 104 confirmed planets among 197 star systems surveyed. Yesterday, NASA announced four more planetary finds, but this time they were all in the same star system– and some of them are in the habitable zone, meaning they could support life. There are a lot of really interesting facts uncovered about this star system that were divulged in NASA’s press release on the subject.
What’s the Star Like?
The planets were found in the K2-72 star system. Its sun is much smaller and less massive than our sun, measuring in at about 23% of its size, and 22% of its mass. It is classified as a red dwarf, with its surface temperature coming in at 3497 degrees Kelvin – compared to the Sun’s 5778 degrees Kelvin. Below, I put together a comparison image, showing both its size and color.
What About the Planets?
The planets are where there are some really interesting details. They are all relatively close to each other, and their orbit is closer to their star than Mercury is to ours. While you might think that this would make them uninhabitable, the much smaller and lower energy star puts out about the right amount of radiation to make two of them potentially habitable. Also, because they are so close, their years, or how long they take to make one orbit, ranges from only 5 to 24 days. From a size perspective, they are all larger than Earth – 20% to 50% larger.
How Does NASA Know Planets are There?
Planets are found by continually observing a star and measuring its luminosity. When a planet crosses in front of a star, it blocks a small amount of its light, causing the luminosity to drop slightly.
Feature image credit: NASA/JPL
Tek22 
Reblogged this on John's Notes and commented:
It is amazing how far we have come in discovering exoplanets. When the James Webb Space Telescope is launched in late 2018, the ability to observe exoplanets will be enhanced.