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Scientists used to wonder how common planets were throughout the universe, and now we know. They're extremely common. They're so common, in fact, it's possible simply to find some other one while you're trying to gather information on the one you already knew almost. That'due south what happened when astronomers recently turned their attention to the star K2-18. They found a bonus planet.

The first exoplanet around this star, dubbed K2-18b, was discovered in 2015 by the Kepler Infinite Observatory. This musical instrument got a new lease on life when NASA engineers managed to compensate for the failure of its reaction wheels. It couldn't maintain orientation also as before, just information technology's "K2" phase nonetheless allowed it to spot many exoplanets similar K2-18b. Kepler uses the transit method to spot planets — when a world passes in front of its host star, there'southward a small drop in light. That'south enough to strongly suggest a planet, but astronomers ever need to follow up.

In the case of K2-18b, astronomers began observing information technology with the European Southern Observatory'due south planet-hunting HARPS musical instrument, which is part of the 3.6-meter telescope in the La Silla Observatory. It appeared to be a super-Earth, a rocky planet more massive than World, only Kepler couldn't tell us for sure. HARPS allowed the team to track K2-eighteen's radial velocity equally K2-18b orbited it. These fluctuations allowed the team to determine the planet is in the habitable zone of the star and is probably composed of either rock or h2o and ice. Either style, there'due south some possibility it could support life.

The HARPS instrument.

While monitoring K2-18b, the team picked upwards another bespeak that Kepler missed. It turned out to be another planet much closer to the star. This planet, now known as K2-18c, also looks similar a super-Earth. Nonetheless, it'south so close to the star that its temperature exceeds the boiling point of water. That makes information technology a poor candidate for life as we know it.

It'southward remarkable we've been able to learn and so much almost a solar system more than 111 light years away, but this is only the beginning. Scientists are excited to run across more than planets orbiting red dwarf stars similar K2-18. Another important exoplanet finds have been orbiting carmine dwarfs, like the 1 correct adjacent door in the Proxima Centauri system. Not only are these stars plentiful and long-lived, but they're also good targets for study with the upcoming James Webb Telescope. That instrument should exist online in 2019.