I’ll be honest, some of the thrill of reporting on the discovery of Earth-like planets has been dampened by the sheer frequency of discovery. Since Alphr has been a thing, I’ve reported on the discovery of Kepler-452b, Proxima Centauri b, Gliese 1132 b, and a star with not one, not two but SEVEN Earth-like planets orbiting it. I’m getting world-fatigue.
But there’s another reason why these discoveries feel a little hollow: there’s just no way of getting to them. The closest of these planets – Proxima Centauri b – was 4.25 light years away, which is really close in intergalactic terms, but with speeds matching New Horizons, you’re still looking at a travel time of around 78,000 years. So you’re definitely going to die on Earth, or in an extremely misguided attempt to make the trip.
That’s 4.25 light years away. The latest batch of planets has been found in the Cygnus constellation, which is some 380 light years away. You do the maths.
Well, now that I’ve completely killed the fun of planet discovery, let me try and pick things up again, because there’s a particularly interesting nugget about planet formations to come. First, the basics: NASA’s latest haul contained a whopping 219 planet candidates, of which ten are roughly the same size as Earth, with a similar distance to their respective host stars. That puts them firmly in the Goldilocks zone: the sweet spot where liquid water can form without freezing or evaporating. That, in turn, is important because liquid water is – to our understanding – essential for life as we know it to develop.
“The Kepler dataset is unique, as it is the only one containing a population of these near Earth-analogues – planets with roughly the same size and orbit as Earth,” explained Kepler program scientist Mario Perez. “Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth.”
Right, I promised you the planet formation nugget earlier, so here it is: the team discovered that planets below 1.75 times the size of Earth tend to be rocky worlds, while two to 3.5 times the size of Earth are gaseous, like Neptune. “It’s like finding what we thought was a single species of animal is really two different things,” astronomy graduate student Benjamin Fulton told The Guardian.
The Kepler telescope has now found 4,034 planet candidates since launching in 2009. Of those, 49 are Earth-sized and in the habitable zone. That’s likely to be it for now though, as the telescope enters its K2 mission. This involves examining sky regions for time periods that are likely too short to confirm a new planet (three transits are required to confirm a planet, so you’d need a very short orbit to spot anything new).
Still, it’s not a bad haul, and there’s plenty for astronomers to get their teeth into – which will be all the easier when the James Webb telescope launches next year.
Images: NASA and The University of Hawaii
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