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Using a new technique, astronomers with the Kepler space telescope have confirmed a whole bunch of new exoplanets. And other astronomers have announced that mega-tsunamis were probably involved in shaping Mars' terrain.

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[SciShow Space intro plays]

Caitlin: Last week, astronomers working with the Kepler space telescope announced that they’d confirmed 1,284 new exoplanets at once. Which is a lot of planets! In fact, it’s the biggest collection of planets ever confirmed at once -- thanks to a new method developed by the researchers, who published their findings in The Astrophysical Journal.

Astronomers usually confirm exoplanets a few at a time, going through the data for each one by hand. But for this study, they created a computer program to statistically analyze all 7,056 Kepler Objects of Interest, or KOIs -- things that might be exoplanets.

It’s hard to detect planets around other stars using direct imaging, because the glare from the star outshines any planets orbiting it. Instead, Kepler monitors the light from a star to look for potential exoplanets -- because when a planet passes in front of its parent star, it blocks some of the light. But a dip in the measured light doesn’t always mean a planet is blocking the starlight. For example, it could be a binary star system, with a second star passing in front of the first and changing the spectrum of the light we see from Earth.

Until now, astronomers have analyzed the evidence for each KOI individually, considering all the options and coming up with a probability that each possible exoplanet is an actual exoplanet. If the odds it’s a planet are above 99%, it’s considered confirmed. Computer models have been developed to help confirm exoplanets. But to work, they still needed the scientists to figure out and input the properties of each host star, like its mass and radius. For this study, the astronomers came up with a program that would analyze the host star, and then find the probability that the KOI was an exoplanet.

Using this method, they confirmed more than a thousand new exoplanets, and identified 428 KOIs that are probably just false positives. That’s way faster than analyzing each of them individually, but just as accurate! Of the newly-confirmed exoplanets, 550 of them are the right size to be rocky planets. And 9 are within the habitable zones of their parent stars -- meaning that life as we know it might be able to survive there. That brings the total number of known exoplanets in their stars’ habitable zones up to 21. So now astronomers have a new set of exoplanets to study, and a much quicker way to check if KOIs are actually planets orbiting stars.

Meanwhile, we’re still learning new things about the planets orbiting our own star. Like yesterday, when a group of astronomers announced that mega-tsunamis on Mars probably helped shape the Red Planet’s terrain, in a paper published in Nature Scientific Reports. Tsunamis on Mars!

The researchers were trying to figure out what formed the northern plains on Mars. For a long time, astronomers thought that the plains were shaped around 3.4 billion years ago by a huge Martian ocean. Problem is, oceans tend to create shorelines with consistent elevations. But the northern plains have geologic features at all kinds of different elevations. Using a computer model of Martian geology, the team found that huge tsunamis could have created those features, washing water out from the ocean in giant, 120-meter waves.

Asteroid impacts that formed at least two of the craters in the northern plains could have caused these tsunamis -- probably about 3 million years apart. The more recent tsunami would have spread lots of water across the plains, which would have frozen into water ice. Because the ancient Martian ocean was so salty, it probably took tens of millions of years to freeze, which would have been plenty of time for ancient Martian life to establish an ecosystem. After all, life can survive in salty liquid water here on Earth. So these ancient ice water deposits could be a great place to look for signs of ancient life -- and some of them aren’t too far from where NASA’s Pathfinder mission landed in 1997. Might be time for another trip.

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