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What An Earth-Like World Around Proxima Centauri Would (And Wouldn’t) Mean

“Whether this planet exists or not — and it’s important to be skeptical, as there was a planet reported around Alpha Centauri B a few years ago that went away with more data — it’s important to remember that ‘Earth-like’ is a far cry from being anything at all like the actual Earth. By these criteria, Venus or Mars would be ‘Earth-like’ too, but you wouldn’t stake your hopes of becoming an interstellar species on either of those. As great as finding a new, rocky world in the potentially habitable zone around the nearest star to the Sun would be, it’s a long way from our ultimate dream of an Earth 2.0.”

Later tonight, the European Southern Observatory is expected to make an announcement, and the smart money is on the discovery of an Earth-like planet orbiting Proxima Centauri, the nearest star to our Sun. As incredibly exciting as this news is, however, it’s important to keep in mind that “Earth-like,” to an astronomer, means something very different than what we think of as “actually like Earth.” The only information we can glean from our present observations is the planet’s mass, size and orbit around a star. This is enough to tell us some of its properties, including a few ways (like tidal locking) that are quite different from Earth, but questions about its atmosphere, surface temperature, magnetic field and much more remain unanswered.

Come learn what the discovery of a new planet around our closest star would and wouldn’t tell us!

Scientists just discovered the closest Earth-like planet ever

It seems the rumors about a new exoplanet in our backyard are true. Scientists have discovered a small, rocky exoplanet orbiting around our closest star, Proxima Centauri. The planet, named Proxima b, is about 1.3 times the size of Earth. Scientists think it’s warm enough to sustain an important resource.
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Does the closest star to our Sun have planets? No one is sure, but you can now follow frequent updates of a new search that is taking place during the first few months of this year. The closest star, Proxima Centauri, is the nearest member of the Alpha Centauri star system. Light takes only 4.24 years to reach us from Proxima Centauri. This small red star, captured in the center of the featured image by the Hubble Space Telescope, is so faint that it was only discovered in 1915 and is only visible through a telescope. Telescope-created X-shaped diffraction spikes surround Proxima Centauri, while several stars further out in our Milky Way Galaxy are visible in the background. The brightest star in the Alpha Centauri system is quite similar to our Sun, has been known as long as recorded history, and is the third brightest star in the night sky. The Alpha Centauri system is primarily visible from Earth’s Southern Hemisphere. Starting last week, the European Southern Observatory’s Pale Red Dot project began investigating slight changes in Proxima Centauri to see if they result from a planet – possibly an Earth-sized planet. Although unlikely, were a modern civilization found living on a planet orbiting Proxima Centauri, its proximity makes it a reasonable possibility that humanity could communicate with them.

Image Credit: ESA/Hubble & NASA


How Science Can Learn More About ‘Proxima b’ And All Earth-Like Worlds

“This planet is almost definitely tidally locked to its star, meaning that the same hemisphere always faces the star and the opposite hemisphere always faces away, just like the Moon does to Earth. The star itself is active and flares frequently, meaning that catastrophic radiation impacts the Sun-facing side quite regularly, but never touches the dark side. And the “seasons” are determined by the ellipticity of its orbit, rather than its axial tilt. But there’s still so much left to learn, and we have a number of different technological avenues to explore – including potentially all of them – if we want to learn more about it.”

Now that we’ve learned the nearest star to our Sun, Proxima Centauri, has a rocky planet at the right distance for liquid water, it’s time to consider how we might learn the answers to our burning questions about it and all nearby Earth-like exoplanets. What’s the atmosphere like, and what does it consist of? What does the surface of the world look like, and what’s on it? And is there life, or intelligent life, present at all? There are three ways to conduct these searches, and they’re all complementary. We can use giant ground-based telescopes, including arrays of telescopes, for high-resolution spectroscopic images of these worlds. We can use space-based telescopes with coronagraphs or starshades to image these worlds directly over time. Or we could undertake a journey across space, and visit the system directly to obtain in situ measurements we could never get from afar.

If this doesn’t inspire you to invest in astronomy and learning more about the Universe, perhaps nothing will!


Ten Ways ‘Proxima b’ Is Different From Earth

“5.) Plants on the surface couldn’t use UV light. Even though Proxima b is much closer to its star than Earth is to the Sun, Proxima Centauri is so much cooler and dimmer that there’s practically no ultraviolet light emitted from it. In fact, there’s practically no blue light, either, meaning that many of the same molecules that plants use to get energy on Earth wouldn’t work on Proxima b. Life would have to find another way.”

The discovery of a potentially habitable planet around the nearest star to our own – Proxima Centauri – has brought up the tantalizing possibility that this might be closest Earth-like world ever found. But it’s important to realize that as much as we’d love to find a world humans could inhabit and colonize beyond our Solar System, there’s a big difference between calling something “Earth-like” and having it actually be like Earth. While Proxima b and Earth have many things in common, mass, size, flux received from their star, etc., they also have many striking differences. Some of these would be noticeable at day, others at night, and others still would make a habitable world as we recognize it extraordinarily unlikely, or at least very different from the the one we know.

Come learn ten of the ways Proxima b is different than Earth, and see how many you already knew!