Note: I apologize un-Romney-like for the apparent tardiness of this posting, but I just returned to home and the internet from a month-long refuge in Brooklyn after evacuating the Rockaways from Hurricane Sandy. I survived, safe and sound, but the same cannot be said of what was — aside from several books and a laptop — my only other worldly possession: a 30″ flat-screen HDTV that was summarily sequestrated, not by Congress but equally criminal post-storm looters who rampaged unmolested in the storm’s lawless wake. Oh, well…. Above, artist’s rendition of exo-Earths orbiting a sun-like star. More on superstorm Sandy will follow soon, but now, having paid my personal Pearl Harbor tribute earlier today, more news from space:
From Ohio State University Research News:
Search for Life Suggests Solar Systems More Habitable than Ours
SAN FRANCISCO—Scattered around the Milky Way are stars that resemble our own sun—but a new study is finding that any planets orbiting those stars may very well be hotter and more dynamic than Earth.
That’s because the interiors of any terrestrial planets in these systems are likely warmer than Earth—up to 25 percent warmer, which would make them more geologically active and more likely to retain enough liquid water to support life, at least in its microbial form.
The preliminary finding comes from geologists and astronomers at Ohio State University who have teamed up to search for alien life in a new way.
They studied eight “solar twins” of our sun—stars that very closely match the sun in size, age, and overall composition—in order to measure the amounts of radioactive elements they contain. Those stars came from a dataset recorded by the High Accuracy Radial Velocity Planet Searcher spectrometer at the European Southern Observatory in Chile.
They searched the solar twins for elements such as thorium and uranium, which are essential to Earth’s plate tectonics because they warm our planet’s interior. Plate tectonics helps maintain water on the surface of the Earth, so the existence of plate tectonics is sometimes taken as an indicator of a planet’s hospitality to life.
Of the eight solar twins they’ve studied so far, seven appear to contain much more thorium than our sun—which suggests that any planets orbiting those stars probably contain more thorium, too. That, in turn, means that the interior of the planets are probably warmer than ours.
For example, one star in the survey contains 2.5 times more thorium than our sun, said Ohio State doctoral student Cayman Unterborn. According to his measurements, terrestrial planets that formed around that star probably generate 25 percent more internal heat than Earth does, allowing for plate tectonics to persist longer through a planet’s history, giving more time for live to arise.
“If it turns out that these planets are warmer than we previously thought, then we can effectively increase the size of the habitable zone around these stars by pushing the habitable zone farther from the host star, and consider more of those planets hospitable to microbial life,” said Unterborn, who presented the results at the American Geophysical Union meeting in San Francisco this week.
“If it turns out that these planets are warmer than we previously thought, then we can effectively increase the size of the habitable zone around these stars…”
“At this point, all we can say for sure is that there is some natural variation in the amount of radioactive elements inside stars like ours,” he added. “With only nine samples including the sun, we can’t say much about the full extent of that variation throughout the galaxy. But from what we know about planet formation, we do know that the planets around those stars probably exhibit the same variation, which has implications for the possibility of life.”
His advisor, Wendy Panero, associate professor in the School of Earth Sciences at Ohio State, explained that radioactive elements such as thorium, uranium, and potassium are present within Earth’s mantle. These elements heat the planet from the inside, in a way that is completely separate from the heat emanating from Earth’s core.
“The core is hot because it started out hot,” Panero said. “But the core isn’t our only heat source. A comparable contributor is the slow radioactive decay of elements that were here when the Earth formed. Without radioactivity, there wouldn’t be enough heat to drive the plate tectonics that maintains surface oceans on Earth.”
The relationship between plate tectonics and surface water is complex and not completely understood. Panero called it “one of the great mysteries in the geosciences.” But researchers are beginning to suspect that the same forces of heat convection in the mantle that move Earth’s crust somehow regulate the amount of water in the oceans, too.
“It seems that if a planet is to retain an ocean over geologic timescales, it needs some kind of crust ‘recycling system,’ and for us that’s mantle convection,” Unterborn said.
In particular, microbial life on Earth benefits from subsurface heat. Scores of microbes known as archaea do not rely on the sun for energy, but instead live directly off of heat arising from deep inside the Earth.
On Earth, most of the heat from radioactive decay comes from uranium. Planets rich in thorium, which is more energetic than uranium and has a longer half-life, would “run” hotter and remain hot longer, he said, which gives them more time to develop life.
As to why our solar system has less thorium, Unterborn said it’s likely the luck of the draw.
“It all starts with supernovae. The elements created in a supernova determine the materials that are available for new stars and planets to form. The solar twins we studied are scattered around the galaxy, so they all formed from different supernovae. It just so happens that they had more thorium available when they formed than we did.”
Jennifer Johnson, associate professor of astronomy at Ohio State and co-author of the study, cautioned that the results are preliminary. “All signs are pointing to yes—that there is a difference in the abundance of radioactive elements in these stars, but we need to see how robust the result is,” she said.
Next, Unterborn wants to do a detailed statistical analysis of noise in the HARPS data to improve the accuracy of his computer models. Then he will seek telescope time to look for more solar twins.
This research was funded by Panero’s CAREER award from the National Science Foundation.
— Pam Frost Gorder
My last post (Below) stirred a surprising – to me – level of interest in UFOs but few responses. The comments made, though, were intriguing and the discussion brisk. (I’ve always displayed a distinct preference for quality over quantity.)
At the gentle prodding of the few, but astute and passionate, commenters to that previous proposal, I did some superficial research. In it, I happened upon news that is currently capturing headlines and seducing imaginations of space watchers around the globe: an Earth analog – Earth-like planet – had recently been discovered orbiting our nearest neighboring star in the Milky Way, Alpha Centauri B. It was immediately and appropriately dubbed, Alpha Centauri Bb.
This new discovery is a world that Goldilocks would have little patience for; one of extreme heat beyond the human comfort zone with surface temperatures above 1,200° C. But its binary star system may conceal more clement planets, and is of interest to science not only for its proximity to Earth, but this event marks the beginning of a new technological phase in exo-planet detection – those beyond our solar system. That is where I leave them to their tech-world for travel in more mundane matters.
During that research, I further learned that there exist roughly 2 billion Earth twins in our own Milky Way galaxy, a substantially higher percentage than the “thousands” I used for example in posing my original question. Recently, in 2011, the Jet Propulsion Laboratory calculated that from 1.4 to 2.7 percent of all sun-like stars have earth-like planets in their habitable (also called Goldilocks – not too hot, not too cold) zones, which computes to about 2 billion Earth analogs in the Milky Way alone, and as many as a sextillion in the entire universe.
That being the case, of an overwhelming numerical imbalance toward probability of alien visitors, it seems to me that, even absent any irrefutable proof, the likelihood of advanced (sapient) extraterrestrial life is practically a foregone conclusion. I believe it. When I was in college, I saw Arthur C. Clarke (Author, 2001….) on the Tonight Show; Johnny Carson asked him a similar question. He laughed and said, “The universe is so vast, the probability of duplicates so high, I would be astonished if, at this very moment, there were not hundreds of other planets across the universe with people sitting in front of TVs tuned to the Tonight Show on each one!”
I discovered too, in my evidentiary search, a photo (shown above) that, if the claims of its subject matter and location are factual, is truly extraordinary. (See later Post, Above) It purports to show Travis Walton — the single-most-significant and recognizable UFO abductee (Nov., 1975; Snowflake, Arizona) — not in Kansas any more, or Arizona, standing in the doorway of an alien spacecraft, in a hangar at its home base — presumably an Earth analog planet.
Another photo that I found in that hunt was of an extraordinary hyper-sonic jet aircraft design that works around sonic boom and totally defeats it. It can achieve Mach-5 in sonic silence. (boomless)