Scientists find ‘Earth-like’ planet

‘Proxima b’ circling sun’s nearest neighbor Planet among the most stunning

SYDNEY, Aug 25, (RTRS): Scientists have discovered a planet that appears to be similar to Earth circling the star closest to the sun, potentially a major step in the quest to find out if life exists elsewhere in the universe, research published on Wednesday showed.

The relative proximity of the planet, known as Proxima b, gives scientists a better chance to eventually capture an image of it, to help them establish whether it has an atmosphere and water, which is believed to be necessary for life.

Future studies may reveal if any atmosphere contains tell-tale chemicals of biological life, such as methane, according to a paper published in this week’s issue of the journal Nature.

“The key question of our initiative was whether there were potentially life-bearing planets orbiting these stars. We know now there is at least one planet with some characteristics similar to the Earth,” said Pete Worden, a former top NASA manager, who was speaking at a European Southern Observatory webcast news conference to announce the find.

The planet, located about 4.2 light-years from Earth, or 25 trillion miles (40 trillion km), is the closest of some 3,500 planets that have been discovered beyond the solar system since 1995, according to the paper.

“This planetary system is much closer than any other that we know so detailed investigation is easier,” astronomer Ansgar Reiners, with the University of Gottingen in Germany, told reporters on a conference call.

Astronomers got their first hint of a planet circling the sun’s small dim neighbor star in 2013. But they needed additional observations, using more precise instruments, to make a definitive call.

An international team of 31 scientists found the planet after careful and repeated measurements of slight shifts in the color of the light coming from its host star, Proxima Centauri, which is a small, dim star in the Alpha Centauri system.

The shifts, which astronomers call “wobbles,” are caused by the gravitational tugging of a planet roughly 1.3 times the size of Earth on the parent star. Based on the timing of wobbles, scientists determined that PARIS, Aug 25, (AFP): An Earth-like planet orbiting the star closest to our Sun, revealed Wednesday, is the most recent — and among the most stunning — in a string exoplanet discoveries going back 20 years.

Herewith, a backgrounder on the search for life beyond the horizon of our Solar System. WHAT IS AN EXOPLANET? Simple:

any planet outside our Solar System.

The first exoplanet was detected in 1995, but the number has exploded in the last few years. A recent statistical study estimated that there a trillion in our galaxy alone.

Today, according to a tally by NASA, there are 3,374 known exoplanets. Of those, 1,248 are so-called ice giants, 990 are gas giants, and 775 are “super Earths” with masses many times higher than the rock we call home.

There are only 347 smaller terrestrial planets with Earth-like mass, and of those only a handful in a “temperate” zone that would allow for the presence of liquid water — a key ingredient for life (as we know it).

None of these were within reach until today, with the discovery of Proxima b, revealed Wednesday.

HOW ARE EXOPLANETS DETECTED?

There are several ways to find planets that cannot be directly observed, according to NASA.

the planet circles its host star in just 11 days, compared to Earth’s 365day orbit around the sun.

That puts the planet far closer to its parent star than Earth orbits the sun. However, Proxima Centauri is so much smaller and dimmer than the sun that its planet’s orbit is suitably positioned for liquid water despite being just 4.4 million miles away.

Viable

“Chances are good that it’s a viable, Earth-like planet today,” said astronomer Pedro Amado, with the Instituto de Astrofsica de Andaluca in Granada, Spain.

But scientists are unsure if red dwarf stars like Proxima Centauri are good hosts for life. Planets orbiting

— This involves looking for changes in the colour spectrum emitted by a star due to the gravitational pull of one or more invisible planets.

If these patterns are regular and cyclical, corresponding to a tiny wobble in the star, chances are they are caused by a planet. Also called radial velocity, this is how Proxima b was discovered. Exoplanets found this way: 17.6 percent.

SHADOW SEARCHING

— When a planet passes directly between its star and an observer — an astronomer peering through a telescope, or a satellite in space — it dims the star’s light by a tiny but measurable amount. This transit method has been the most successful so far — NASA’s Kepler spacecraft used it to find thousands of candidate planets from 2009 to 2013. Obviously, if a planet doesn’t happen to be on the same plane as the star AND the observer, it doesn’t work. Exoplanets found this way: 79 percent.

PICTURE PRODUCING

— Snapping a picture of an exoplanet in front of its star is something like trying to photograph a microscopic speck of dust on a glowing lightbulb. But by removing the blinding glare of the star, astronomers can capture an image, a method called direct imaging. Only a tiny fraction of distant planets have been detected this way: 1.2 percent.

BEAM BENDING — In another

close enough to keep water liquid would be blasted with 100 times more high-energy radiation than Earth receives from the sun, though what impact that would have on life is a matter of scientific debate.

“We don’t think it’s a show-stopper,” Amado said.

Magnetic fields and an atmosphere offer a planet some protection. It is unknown if Proxima b has either.

Before the discovery of Proxima b, the nearest Earth-like planet to the sun was circling a star known as Wolf 1061, located about 14 lightyears away.

Proxima b may not be flying solo. “We have some suspicions that there is another signal around the star,” Reiners said.

technique, light from a distant star is bent and focused by gravity as an orbiting planet passes between the star an Earth.

Called gravitational micro-lensing, the gravity of the planet and star focus light rays of the distant planet on an observer in the same way that a magnifying glass focuses the Sun’s light onto a tiny, bright spot. Only a handful of exoplanets have been found using this method.

WHAT CONDITIONS SUPPORT LIFE?

That depends on what the meaning of “life” is!

For life as we know it, liquid water is an essential ingredient. Of the exoplanets found to date, however, only a handful are in a “temperate” zone in relation to their star: not so hot that water evaporate, not so cold that it freezes rock solid.

Life on Earth is also unimaginable without an atmosphere, containing in our case the oxygen we need to survive. An atmosphere also protects animal species in particular from damaging high-energy radiation from the Sun — ultraviolet and X-rays.

But as we do not even know yet how life emerged on Earth, it is also possible that living creatures elsewhere in the Universe could survive and thrive in conditions that would be lethal for our tender-footed species.

More research is needed to determine if there are multiple planets circling Proxima Centauri.

The discovery announced on Wednesday is expected to bolster a $100 million project unveiled in April and backed by Russian billionaire Yuri Milner to develop a miniature laser-powered spacecraft that can make the trip to the Alpha Centauri system in about 20 years.

“We hope to build a whole system that will send nanocraft to Proxima Centauri and Alpha Centauri within a generation,” said Worden, the executive director of Breakthrough Starshot, an initiative that aims to deploy thousands of tiny spacecraft to travel to our nearest neighboring star system and send back pictures.