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Does an Earth-like planet orbit around Proxima Centauri?

Proxima Centauri, as imaged by the Hubble Space Telescope in 2013. Could an Earth-like planet be orbiting this red dwarf star? Credit: ESA/Hubble & NASA

Scott Sutherland
Meteorologist/Science Writer

Thursday, August 18, 2016, 3:30 PM - Our closest stellar neighbor may have an Earth-like planet, NASA's mission to a potentially-hazardous asteroid leaves in a few short weeks and a strange object has been found in the outer solar system. It's What's Up In Space!

An "Earth-like" exoplanet just next door?

At the beginning of 2016, a group of astronomers started a new project called Pale Red Dot. The goal of this project was to use telescopes here on Earth to look for planets that might be orbiting around Proxima Centauri, the closest star to us.

Now, you may have heard reports of an "Earth-like" exoplanet found around one of the stars of Alpha Centauri, which is the closest star system to our own, and subsequent findings that first told how this planet would be far too hot to sustain liquid water or life, and how it may not even exist (and in all likelihood does not).

Pale Red Dot, however, was taking advantage of some specific stellar alignments to take the search to the small red dwarf star, Proxima Centauri, which orbits in a wide path around both Alpha Centauri a & b, and is currently the closest star to our Sun. Astronomers had noticed that, from our perspective here on Earth, Proxima Centauri would pass very close to two different stars as it traced a path across the sky.

The gravitational lensing opportunities to planet-hunt around Proxima Centauri. Credit: NASA/ESA/Hubble

Credit: Hubble/A. Feild (STScI)

At these two times, Proxima Centauri, as well as any planets that might orbit around the star, would produce a gravitational lens, which would bend the light from those two stars. If the positions of the more distant stars simply shifted away from Proxima Centauri as it passed by in the foreground, then in all likelihood the red dwarf would be alone. If the shift in position of the distant star was skewed, however, it could signify that Proxima Centauri had company - one or more exoplanets!

This first Pale Red Dot campaign ended on April 1, 2016, and the results are apparently due out towards the end of this month, but there has been talk on the internet that they really have found something!

The German news source Der Spiegel reported last week that a source had revealed to them that Pale Red Dot had indeed spotted a planet orbiting around Proxima Centauri. Not only that, but this planet was apparently inside the star's habitable zone, which means that it would be just warm enough that liquid water could exist on its surface. If both of these reports turn out to be true, that would make this exoplanet (Proxima Centauri b?) a potential candidate to harbour alien life!

There's a caveat here beyond simply saying that "the results aren't out yet" and "subsequent studies may show that the planet isn't there," though. Even if Proxima Centauri has a rocky, Earth-sized planet orbiting in its habitable zone, there's no guarantee that it will actually have life. Red dwarf stars, although the longest-lived of all stars, are notoriously temperamental, and frequently blast out immense flares and solar eruptions. Proxima Centauri is no exception to this rule, and with the habitable zone of a red dwarf being much closer in than for a Sun-like star, this planet could be regularly bathed in intense stellar radiation, possibly rendering it sterile.

If all of this turns out to be true, however, it will still be pretty amazing. This planet would not only be the closest exoplanet to us, but also the closest potentially-habitable exoplanet to us. It's distance of 4.24 light years - over 40 trillion kilometres - means that we wouldn't be visiting it anytime soon, but perhaps it would give a solid target for the tiny starships of Breakthrough Starshot in the years to come.

Gearing up for OSIRIS-REx!

In just a few short weeks, on the night of Thursday, September 8, NASA will be launching a "sample return" mission to asteroid 101955 Bennu, a massive rock in space with the potential for a dangerous interaction with Earth sometime during the late 22nd century.

OSIRIS-REx - the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer - is part of NASA's New Frontiers program, and after its successful launch, will spend roughly 2 years travelling through space to rendezvous with Bennu in 2018.

There, the spacecraft will orbit the asteroid, mapping its features for a period of nearly a year and a half, before coming in to touch its surface, gather a sample, and then launch itself back to Earth for a 2023 return.

The instrument that will be used to map Bennu, the OSIRIS-REx Laser Altimeter (OLA), was supplied by the Canadian Space Agency, and CSA mission manager, Tim Haltigin, who is directing the Canadian contributions to the mission, describes the mission and its goals in the video below.

Not only is this trip to Bennu one of scientific exploration, but it is also going to be key for the defense of our planet. Knowing what Bennu is composed of will provide us a better understanding of asteroids in general, and OSIRIS-REx's operations around the asteroid will give us an idea of what it will take to deflect potentially dangerous asteroid that may impact with Earth at some point in the future.

A weird "backwards" object beyond Neptune

Astronomers keeping a watch on the outer reaches of our solar system, and specifically the objects that are known to orbit just beyond Neptune - the trans-Neptunian objects - have discovered something strange.

An object roughly 200 kilometres wide and likely composed mainly of ice, which has been nicknamed "Niku" (Chinese for "rebellious"), was found to have a very unusual orbit, and it shared the plane of its orbit in a very unexpected way with a collection of other objects.

As Dr. Matthew J. Holman, one of the astronomers who discovered Niku, from the Harvard-Smithsonian Center for Astrophysics, told Universe Today:

"The orbit of Niku is unusual in that it is nearly perpendicular to the plane of the Solar System. More than that, it is orbiting in the opposite direction of most Solar System bodies. Furthermore, there are a few bodies that share the same or orbital plane, with some orbiting prograde and some orbiting retrograde. That was unexpected."

Could this be more evidence for the existence of an as-of-yet undiscovered planet in the outer solar system?

The research on Niku is available on arXiv.

Sources: Der Spiegel | Hubble | NASA | Universe Today

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