UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

Observing the auroras can help researchers characterize the planet's atmosphere. On Earth, the different color glow of the northern and southern lights corresponds to reactions with different molecules in the atmosphere. According to Luger, who presented the results at the Astrobiology Science Conference in Mesa, Arizona, in April, if Proxima Centauri b is a terrestrial world with an Earth-like atmosphere and a magnetic field, the green light of the oxygen auroras would grow 100 times stronger than on Earth.

Because of the potential for green light, the researchers dubbed such a world "the pale green dot," a nod to Carl Sagan's categorization of Earth as a pale blue dot.

Periods of intense stellar activity could make the auroras even brighter. While coronal mass ejections and flares have the strongest impact on generating auroras, Luger said, they aren't really predictable in advance.

"But the sun certainly has periodic activity cycles, so if we understand those of Proxima Centauri, we might be able to use that to our advantage," he said.

He went on to say that the extreme activity of the star may make such knowledge unnecessary — astronomers could simply count on a high likelihood that the star would flare and cause the auroras to brighten.

Charged particles and magnetic fields could make Proxima Centauri b glow green, as in this photo of Earth taken by European Space Agency astronaut Alexander Gerst from the International Space Station. — **Credit: Alexander Gerst (via Twitter as @Astro_Alex)**

Optimal for auroras

While several studies have described searches for auroras on gas giant exoplanets that orbit close to their parent stars, none have been spotted on worlds beyond the solar system. But Luger remains confident.

"Proxima Centauri b is optimal for auroral detection," he said.

He gave several reasons that auroras may be soon spotted on Proxima Centauri b. The planet is nearby — it's the closest known exoplanet to Earth — making it easier for instruments to collect detailed observations. The extreme magnetic activity of the star, coupled with the planet's close orbit, means Proxima Centauri b is bombarded with solar particles far more vigorously than Earth. At the same time, the star is faint, so a glowing green planet would show up more easily than it would around a sun-like star. Finally, the short orbit means that the world moves around its sun at a rapid clip; when a light source is moving toward or away from an observer, this motion can be observed through a phenomenon called redshift, or Doppler shift. Luger said the Doppler shift of the auroras' light waves would be significantly larger than they would be on their own, making lines that would otherwise be hard to see more visible. That would make it easier to identify any oxygen in the atmosphere.

Unfortunately, this "pale green dot" won't be spotted with current telescopes. NASA's upcoming powerhouse telescope ― the James Webb Space Telescope ― will hunt for infrared light, so Luger said it won't be able to detect the green oxygen aurora, which is in the visible light range.

"Our best bet for detection is the [Thirty-Meter Telescope] or similar next-generation extremely large telescopes," he said.

The Thirty-Meter Telescope (TMT) — so-named because its primary mirror would be 30 meters (98 feet) wide — began construction on Hawaii's Mauna Kea peak before it was halted in 2015 after protests over the sacred nature of the land. The project remains at a halt today, though some astronomers have lauded the benefits of moving the telescope to Spain's Canary Islands.

But even TMT would take some time to identify the signature of oxygen from the auroras, with Luger estimating "tens of hours" of observation. The same is true for the Large UV/Opitcal/Infrared Survey (LUVOIR), a proposed design for a telescope with a primary mirror between 9 and 15 meters (30 and 50 feet). With telescope time extremely competitive, it could be hard to study the system so extensively.

In order to produce auroras, a planet must have a magnetic field. Out of the four terrestrial planets in Earth's solar system, only two have a worldwide field — Earth and Mercury. Mars has a patchy field, and Venus has none. If Proxima Centauri b is similarly lacking, it might not produce auroras.

However, the planet may get a brightness boost from airglow, the faint emission of light from the atmosphere that keeps nighttime on Earth from ever being completely dark.

"The planet is likely also to have strong airglow, which is planetwide," Luger said. "Airglow is not generated by magnetic fields, and is typically weaker than aurorae, so we did not calculate it. But it should be quite strong on Proxima Centauri b, and could cause the entire planet to glow green."

The research was published in the Astrophysical Journal.

Follow Nola Taylor Redd at @NolaTRedd, Facebook, or Google+. Follow us at @Spacedotcom, Facebook or Google+. Originally published on Space.com.

Sometime between 3.7 and 4.5 billion years ago, life appeared on earth. How exactly it materialized from the primordial goop, however, is still a fundamental mystery about our planet — one that a group of scientists from McMaster University and the Max Planck Institute say they are one step closer to solving. Darwin, they argue in a new study, may have been right all along: It seems that life really did emerge in earth’s “warm little ponds.”

In a paper published Monday in the Proceedings of the National Academy of Sciences, they posit that life on Earth started out in ancient hot tubs — warm pools of water that emerged as the continents rose out of the early global ocean. Using data from a new numerical model that simulates the conditions of the ancient earth, they explain that the building blocks of life could indeed have emerged if the right interstellar ingredients were added to the mix.

“In order to understand the origin of life, we need to understand Earth as it was billions of years ago,” co-author Thomas Henning, Ph.D., explained in a statement. “As our study shows, astronomy provides a vital part of the answer. The details of how our solar system formed have direct consequences for the origin of life on Earth.”

A figure representing the various influences acting on chemicals in warm little ponds during the dry phase and wet phase of the cycle.

Their argument relies on the assumption that the early earth was bombarded with meteorites that carried life-starting essential elements. As the meteorites crashed into these ponds, they leached their contents into the water over numerous wet and dry cycles. In this hot soup, the first RNA polymers — precursors to relatively more complicated DNA — emerged roughly 4.17 billion years ago.

The researchers posit that the world was, at first, inhabited by only RNA-based life. They argue that DNA, which we now consider to be the fundamental building block of life on earth, is “too complex” to have been the first element of life to emerge.

There’s a growing body of evidence showing that meteorites can indeed carry the essential components of nucleotides, the building blocks that make up RNA and DNA. Scientists first realized that there were components of DNA in meteorites in the 1960s, but it wasn’t until 2011 that researchers proved that they were actually created in space and didn’t just represent contamination from terrestrial life. That year, NASA-funded researchers at the Goddard Astrobiology Analytical Laboratory found the nucleobases adenine and guanine, as well as hypoxanthine and xanthine, in samples of comet Wild 2 from NASA’s Stardust mission.

A modern example of a warm little pond in Lassen Volcanic National Park that resembles ancient ponds.

In a competing theory, called panspermia, scientists argue that life didn’t emerge on Earth at all and was instead transported in after developing elsewhere. In panspermia,extraterrestrial life — probably bacterial spores — hitched a ride on bombarding space rocks to our planet.

This theoretical paper is just the first step in gaining a better understanding of how life on Earth began. Next year, the scientists behind it plan on testing their theory in the new Origins of Life laboratory at McMaster University, which will allow them to replicate earth’s pre-life conditions in a sealed environment.