The hunt to learn more about our nearest exoplanet, the Earth-like Proxima b, has come up empty-handed. If the planet ever passes between its star and us, we could rapidly learn a lot about it – but observations show it is unlikely to do so.
When Proxima b was discovered orbiting our closest neighbouring star, Proxima Centauri, two months ago, its mass, which is similar to that of Earth, as well as its location in the habitable zone, created excitement about the possibility of it harbouring life.
The best way to learn more about an exoplanet is to watch it pass between its star and our telescopes, which can yield a wealth of knowledge about the planet’s size, atmosphere and even its surface conditions. Such a transit so close to home would be a monumental result.
Before Proxima b was spotted, David Kipping at Columbia University in New York and his colleagues had spent over 40 days in 2014 and 2015 hunting for planets orbiting Proxima Centauri using the MOST Space Telescope. Once the discovery was announced, they narrowed their search, looking for signals that could match a planetary transit.
“It almost felt like too much to ask for, because it’s such an incredible planet: it’s an Earth-mass planet, at the right distance for life, around the nearest star,” says Kipping. “It’s already checking three boxes that you could optimally hope for in any exoplanet discovery, and we were hoping that it also transits.”
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