2018 was kind of a bittersweet year for space scientists. NASA successfully reached the farthest object in our solar system, landed a small robot on Mars, and even discovered its hidden gigantic lake! But in late October, the Kepler Space Telescope ran out of fuel and came to an end. And after nine years of floating around, it showed us that our universe is even more amazing than we’d imagined. Here is some of what we learned.
NASA’s Kepler Space Telescope was originally going to be called FRESIP, which stood for “FRequency of Earth-Sized Inner Planets.” But thankfully, somebody changed their mind and named it after the famous astronomer instead. The mission launched in 2009, and it used something called the transit method to find planets outside of our solar system. This method studied more than half a million stars, looking for tiny dips in light, which could mean a planet was passing by. And it totally worked!
Less than a year after launch, Kepler found its first planets, a bunch of what scientists call “hot Jupiters.” They’re large gas giants that orbit super close to their stars. We don’t have any of those planets around here, so discoveries like this tell us a lot about how other star systems evolve.
Over its two missions, the main Kepler mission and the K2, the telescope went on to find more than 2700 exoplanets – that’s more than two-thirds of all the exoplanets we know about today! And along the way, it painted a picture of just how diverse our galaxy is. In fact, most of the planets Kepler found are not anything like what we have in our solar system. Instead, they’re somewhere in size between Earth and Neptune. And while it’s pretty easy to find large planets, the fact that there are so many suggests our solar system could be at least a little special.
But not all of Kepler’s discoveries were super weird and wild. It also found planets a little more similar to Earth, and that could help us understand how our home got to be the way it is. For example, in 2011, Kepler found the first real evidence for a rocky exoplanet. Then, in 2014, it found the first roughly Earth-sized planet in its star’s habitable zone. That’s the distance from a star where water could exist on the surface, if a planet has a thick enough atmosphere.
And in 2018, the telescope may have even found the first moon around an exoplanet! Unfortunately, for some time now, Kepler had been running low on the fuel it needed to perform any real movement. And on October 30th last year, NASA announced that it had finally run out. This means we can’t point it toward anything we want to study, or point it back toward Earth to send data home.
So now, it’s just stuck in orbit around the Sun. But it was a really good telescope while it lasted! And while we’re sad to see it go, we can’t wait for March of 2021 for the launch of the James Webb Space Telescope – more powerful than those before it, and able to see further into space to discover planets in far-off galaxies. In other words, the adventure doesn’t end with the Kepler Telescope; more exciting space news is always on the horizon.
- Exoplanet: a planet which orbits a star outside Earth’s solar system
- Habitable zone: the area around a star in which an Earth-like planet may have liquid water on its surface and the potential to support life
- Hot Jupiters: gas giant exoplanets that are physically similar to Jupiter but orbit much closer to their star
- Star system: a very large group of stars which may or may not also include planets
- Transit method: a scientific method that finds distant planets by measuring the brightness of a star as an orbiting planet passes between it and Earth