An Atmosphere Has Been Detected Around an Earth-Like Exoplanet for the First Time


Astronomers have detected an atmosphere around an Earth-like exoplanet called Gliese 1132b (GJ 1132b for short), which is located around 39 light-years away in the constellation Vela.

This is the first time atmosphere has ever been detected around a planet with a mass and radius so similar to Earth’s, and that makes it a hugely promising (and exciting) target for researchers searching for signs of extraterrestrial life.

 

“While this is not the detection of life on another planet, it’s an important step in the right direction: the detection of an atmosphere around the super-Earth GJ 1132b marks the first time that an atmosphere has been detected around an Earth-like planet other than Earth itself,” said lead researcher John Southworthfrom Keele University in the UK.

There’s still a lot to learn about GJ 1132b’s atmosphere, but early observations suggest it could be a “‘water world’ with an atmosphere of hot steam” – AKA, a pretty awesome place to go looking for life.

So far, we know that GJ 1132b has a mass about 1.6 times that of Earth’s, and has roughly 1.4 times its radius – which in terms of exoplanets makes it remarkably similar to our home planet.

But as with all exoplanet discoveries, the researchers are quick to remind the public that the observations to date still really don’t give us much insight into how similar GJ 1132b could be to Earth – or how habitable.

Some bad news upfront is it has an estimated surface temperature of 370 degrees Celsius (698 degrees Fahrenheit), which makes it unlikely that it could host life like us.

And let’s not forget that we’ve recently been burned by the detection of the TRAPPIST-1 ‘sister solar system’ and neighbouring Earth-like planet Proxima b, both of which are unlikely to be the friendly places for life we first thought they were.

 But none of those planets had ever gotten as far as having an atmosphere detected, so GJ 1132b is already doing pretty well in terms of a spot that could potentially host life.

Right now, the top strategy for astronomers in the search for life on another planet is to detect the chemical composition of that planet’s atmosphere, looking for certain chemical imbalances that could hint at the presence of living organisms. For example, on Earth, the large amount of oxygen in our atmosphere is that ‘smoking gun’.

We’re a long way off having that much insight into GJ 1132b, but the fact that we’ve detected its atmosphere at all is a good first step.

The planet orbits the not-too-distant red dwarf star Gliese 1132, which Southworth and his team studied using the ESO/MPG telescope in Chile.

They measured the slight dip in brightness across seven wavelengths of light as GJ1132b passed in front of its host star every 1.6 Earth days, in order to get a better idea of the size and composition of the planet.

They were surprised to find that the planet appeared larger when observed in one type of infrared wavelength of light, which suggests that the planet has an atmosphere that’s opaque to these wavelengths.

The team went on to model different possible versions of this atmosphere, and found that an atmosphere rich in water and methane could explain what they were seeing.

Prior to this, the only exoplanets that researchers have detected atmospheres around were planets that were more than eight times more massive than Earth, and gas giants similar to Jupiter.

“With this research, we have taken the first tentative step into studying the atmospheres of smaller, Earth-like, planets,” said Southworth. “The planet is significantly hotter and a bit larger than Earth, so one possibility is that it is a ‘water world’ with an atmosphere of hot steam.”

The type of star GJ 1132b is orbiting also makes the planet of particular interest – its host star is a low-mass red dwarf, which are incredibly common throughout the Universe and are frequently found to host small, Earth-like planets.

But they’ve also been shown to be particularly active, often blasting huge solar flares out at their surrounding planets – something previous research has suggested would evaporate any traces of a planet’s atmosphere.

But the new discovery suggests that an atmosphere is possible of enduring this bombardment for billions of years without being destroyed – which opens up the possibility that thousands more planets orbiting low-mass stars could potentially harbour atmospheres.

“Given the huge number of very low-mass stars and planets, this could mean that the conditions suitable for life are common in the Universe,” a press release explains.

We still have a lot to learn about GJ 1132b, and hopefully we’ll have some more answers soon – the new discovery makes it one of the highest-priority targets to be studied by instruments such as the Hubble Space Telescope, the Very Large Telescope, and the James Webb Space Telescope, which is scheduled to launch in 2018.

Source:sciencealert.com

Scientists plan on contacting the closest Earth-like exoplanet to our Solar System.


Scientists are making preparations to send a transmission to Proxima b – the closest Earth-like exoplanet to our Solar System.

The team is putting together a plan to build or buy a powerful deep-space transmitter, and is now figuring out what our message should be – after all, we don’t want to make a bad first impression.

“If we want to start an exchange over the course of many generations, we want to learn and share information,” president of the San Francisco-based Messaging Extraterrestrial Intelligence (METI) organisation, Douglas Vakoch, told The Mercury News.

METI’s plan is similar to that of the former NASA mission, Project Cyclops, which was backed by the space agency but shelved in the 1970s due to a lack of funding.

Project Cyclops proposed patching together a network of radio telescopes on Earth to reach out as far as 1,000 light-years into space, and METI has similar ambitions.

The non-profit organisation is planning a series of workshops and a crowdfunding drive to make the scheme a reality – and it’s estimated they’ll need to raise around US$1 million a year to run the transmitter.

By 2018, the team wants to have laser or radio signals beamed out to Proxima b, which orbits Proxima Centauri – the closest star to our Solar System, at around 4.25 light-years away.

Part of METI’s work will be to figure out what we should say, and to consider the possibility that other lifeforms will have developed the same mathematical laws and scientific hypotheses that we have.

 

The researchers at METI also want to reassess the Drake equation, written in 1961 by astrophysicist Frank Drake to calculate how many other civilisations there could be in the Universe, based on factors like star formation rates and the ratio of planets to stars.

But not everyone agrees that broadcasting our existence into the unknown is a such a good idea: in a recent paper in Nature Physics, physicist Mark Buchanan argued that we might be “searching for trouble” if we start flinging messages out into space.

Stephen Hawking agrees, recently arguing that it’s too risky to try and chat to civilisations that are probably far more advanced than we are – lifeforms that could have the same opinion of us that we have of bacteria.

Despite the opposition, the experts at METI are convinced that the benefits of reaching out into space and learning more about our place in the Universe outweigh the risks.

“Perhaps for some civilisations… we need to take the initiative to make first contact,” Vakoch writes in Nature Physics.

“The role of scientists is to test hypotheses. Through METI we can empirically test the hypothesis that transmitting an intentional signal will elicit a reply.”

It won’t be the first time we’ve sent messages out into the void, but METI is planning communications that are more regular and will reach further than ever before.

Perhaps the best argument for METI’s scheme is that someone needs to make the first move, as astronomer Andrew Fraknoi from Foothill College in California, told The Mercury Times.

“If everyone who can send a message decides only to receive messages, it will be a very quiet galaxy,” he says.

Star’s Wobble Could Reveal ‘Earth-Like’ Exoplanet


Star's Wobble Could Reveal 'Earth-Like' Exoplanet

Artistic representation of the potentially habitable exoplanet Gliese 832 c as compared with Earth. Gliese 832 c is represented here as a temperate world covered in clouds. The relative size of the planet in the figure assumes a rocky composition but could be larger for a ice/gas composition.

By studying the electromagnetic spectrum of a star’s light, you can see what elements it contains. You can also deduce its age, mass, stability and spin. As astronomical techniques and technologies have become more sophisticated, alien planets that would have otherwise remained invisible can also be detected via their gravitational tug on their host star.

This mode of exoplanetary detection is known as the “radial velocity method” and it depends on the analysis of the periodic shift in the frequency of starlight to reveal the gravitational fingerprint of orbiting worlds. Basically, by watching a star’s light for a long enough period, astronomers can see a star’s “wobble,” a sure sign that a planet — or a system of planets — is in tow.

Now, a team of astronomers, led by Suman Satyal of the University of Texas at Arlington, has delved into the starlight of a nearby red dwarf star already known to possess two exoplanets, revealing there’s the potential for a third exoplanet, possibly as small and as rocky as Earth, sandwiched between the orbits of the two known worlds.

Gliese 832 is a well-known red dwarf. With a mass around half that of our sun, this diminutive star, located only 16 light-years away, has two exoplanets called Gliese 832b and Gliese 832c. Gliese 832b is the larger of the two and has the widest orbit, located 3.53 AU from its host star. It is also more massive, “weighing in” at around 60 percent the mass of Jupiter. Gliese 832c on the other hand is classified as a “super-Earth” of around five times more massive than Earth. It’s orbit is extremely compact, coming within 0.16 AU of its star. As a comparison, in our solar system, the innermost planet Mercury comes no closer than 0.3 AU to the sun.

Gliese 832c hit the headlines in 2014, lauded as a possible “Earth 2.0.” Though this is certainly a possibility, according to planetary scientists, it is more likely to be a hostile “Venus 2.0” with a thick, life-choking atmosphere.

Both 832b and 832c were detected by astronomers watching the star’s light frequency slightly oscillate, an effect known as Doppler Shift. Much in the same way we hear a higher-pitch siren as a police car approaches compared to when the police car drives away, as a planet’s gravity pulls a star toward us, its wavelength will become more compressed (increasing in frequency). As the planet orbits away, the star will also be pulled away, increasing the light’s wavelength (decreasing the frequency). Through computer analysis of these oscillations, astronomers can “see” the orbits of planets around stars without actually seeing the planets themselves. Within these radial velocity measurements the companion planets’ masses, orbital periods and orbital distances can be deduced by using established Keplerian laws of planetary motion.

Now, by revisiting the Gliese 832 star system, Satyal’s team has taken a high-resolution look at the radial velocity data from the star and used computer modeling to see if another exoplanet “fits” between the orbits of 832b and 832c.

“We obtained several radial velocity curves for varying masses and distances for the middle planet,” they write in a paper published by the arXiv pre-print service.

ANALYSIS: Seeking Earth-Like Alien Worlds in the ‘Venus Zone’

Their analysis reveals that another exoplanet could indeed exist with an orbit between 0.25 to 2.0 AU from the star with a mass of 1 to 15 Earth masses. This range is pretty wide, but it provides an invaluable insight for future observations of the star system. An exoplanet within these orbital constraints would be in a stable orbit and would likely be another super-Earth, possibly a world occupying the star’s habitable zone.

The habitable zone around any star is the region that is neither too hot or too cold, where water could exist in a liquid state on the planetary surface. As we all know, this is one of the key conditions for life (as we know it) to evolve, hence all the excitement whenever any world is discovered orbiting its star within the habitable zone.

It’s worth remembering that Earth orbits the sun at 1 AU, pretty much in the middle of our star’s habitable zone. Red dwarfs are much smaller and therefore cooler, so have far more compact habitable zones. Therefore, to maintain water in a liquid state on a hypothetical “Earth-like” planet orbiting a red dwarf, its orbit would have to be far closer. Red dwarfs have often been sited as key locations for alien life to thrive as, by their nature, they are long-lived and may allow complex life to evolve. But red dwarfs are known to be extremely active, often erupting with powerful flares that would irradiate any planet that orbits too close, requiring that planet to have a very well developed natural shielding in the form of a strong magnetosphere.

As you can see, it’s one thing modeling the possible presence of a small rocky world around a nearby star, but it is quite another to find a true “Earth-like” planet that could support life as we know it. But it’s important to try to at least pull any clues from a star’s slight wobble to potentially help us track down alien worlds with any Earth-like quality.