yovisto:

On January 7, 1610, physicist and astronomer Galileo Galileiturned his new telescope to the nocturnal sky to watch the planet Jupiter and discovered the eponymous four moons of Jupiter, Io, Europa, Ganimede, and Callisto.

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jolalal:

An astronomical chart from Nouveau Larousse illustré (1898).

thenewenlightenmentage:

Should We Expect Other Earth-like Planets At All?

This year has been a spectacular one for exoplanets. New discoveries and new insights have truly pushed the gateway to other worlds even further open.

In the past 12 months we’ve gained increasingly good statistics on the incredible abundance of planets around other stars and their multiplicity. We also finally seem to have evidence that our neighboring star Alpha Centauri B does indeed harbor at least one world. It is by any set of standards, a great haul.

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we-are-star-stuff:

Scientists show that microbes from Earth can survive conditions found on Mars

Astrobiologists have been worried for quite some time now that the Martian surface has been contaminated with microbes originating from Earth - what got there by clinging to all the various probes and artifacts we’ve sent there. But given how severe the conditions are on Mars, it has been generally assumed that this is likely an impossibility.

A recent study now threatens to overturn this sentiment. Researchers from Russia and the U.S. have demonstrated that a hardy bacterium found in Siberia is in fact capable of surviving Mars-like conditions - a revelation that will have profound implications on how we prepare our Mars-bound artifacts for future missions.

To conduct the study, researchers from the University of Florida and the Russian Academy of sciences extracted various strains of bacteria found in the Siberian permafrost off the banks of the Kolyma River — extremophiles that can survive some of the harshest conditions that Earth has to offer. The samples were taken from a depth of 12 to 20 meters (40 to 65 feet) where the soil has an average temperature of -7 °C (19 °F).

The samples were drilled out directly from the depth of the permafrost, and without fluid (which normally serves as lubrication) to avoid any contamination. The microbes that were taken had endured their conditions deep underground for the past 6,000 to 8,000 years.

The team grew larger cultures of these microbes back at the lab at normal temperatures in preparation for the next phase. The researchers took these cultures and exposed them to similar conditions found on Mars, including a severe lack of oxygen, extreme cold temperatures, and very low pressure (about 150 times lower than the Earth’s). The experiment was run over the period of 30 days. Over 10,000 isolates were exposed to these conditions - and they all died.

Except six.

And in fact, these six surviving microbes actually did better under these conditions. Surprised by the result, the researchers took a closer look at the survivors, and following a genetic analysis concluded that they all came from the same genus: an extremely hardy extremophile called Carnobacterium.

Carnobacterium can be found in cold climates around the world, including Alaska and the oxygen-poor waters of Ace Lake in Antarctica.

Indeed, it’s a startlingly common anaerobic organism that doesn’t require oxygen for growth. And in fact, a species of Carnobacterium (CB1) is used as a food additive for vacuum or modified atmosphere-packaged ready-to-eat and processed meats. In other words, it’s the kind of bacterium that could easily make its way onto a probe bound for the Martian surface.

As the researchers note in their study, “the ability of terrestrial microorganisms to grow in the near-surface environment of Mars is of importance to the search for life and protection of that planet from forward contamination by human and robotic exploration.” Moving forward, and despite the fact that Mars has a highly irradiated surface, scientists will now have to ensure complete sterilization of all artifacts bound for the Martian surface.

The study was recently published in the Proceedings of the National Academy of Sciences.

When Apollo 11 descended onto the lunar surface on July 20th, 1969, there were pre-existing concerns that the spacecraft would not be able to leave the moon once it arrived. These fears were certainly not alleviated when Buzz Aldrin accidentally broke the circuit breaker that would be instrumental in their relaunch (not to worry- he fixed it with a felt tip pen because science). Concerns prior to the launch had been so serious that Bill Safire, Nixon’s speech writer, actually drafted a statement for the president to deliver to the American people should a tragedy occur:

“Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace.

“These brave men, Neil Armstrong and Edwin Aldrin, know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice.

“These two men are laying down their lives in mankind’s most noble goal: the search for truth and understanding.

“They will be mourned by their families and friends; they will be mourned by their nation; they will be mourned by the people of the world; they will be mourned by a Mother Earth that dared send two of her sons into the unknown.

“In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood of man.

“In ancient days, men looked at stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood.

“Others will follow, and surely find their way home. Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts.

“For every human being who looks up at the moon in the nights to come will know that there is some corner of another world that is forever mankind.”

The memo was not released until 3 decades later. 

‘Tis the season for holiday decorating and tree-trimming. Not to be left out, astronomers using NASA’s Hubble Space Telescope have photographed a festive-looking nearby planetary nebula called NGC 5189. The intricate structure of this bright gaseous nebula resembles a glass-blown holiday ornament with a glowing ribbon entwined. A spectacular example of this beautiful complexity is seen in the bluish lobes of NGC 5189. Most of the nebula is knotty and filamentary in its structure. As a result of the mass-loss process, the planetary nebula has been created with two nested structures, tilted with respect to each other, that expand away from the center in different directions. This double bipolar or quadrupolar structure could be explained by the presence of a binary companion orbiting the central star and influencing the pattern of mass ejection during its nebula-producing death throes. The remnant of the central star, having lost much of its mass, now lives its final days as a white dwarf. However, there is no visual candidate for the possible companion. The bright golden ring that twists and tilts through the image is made up of a large collection of radial filaments and cometary knots. These are usually formed by the combined action of photo-ionizing radiation and stellar winds.

science-junkie:

NASA’s Cassini spacecraft has delivered a glorious view of Saturn, taken while the spacecraft was in Saturn’s shadow. The cameras were turned toward Saturn and the sun so that the planet and rings are backlit. (The sun is behind the planet, which is shielding the cameras from direct sunlight.) In addition to the visual splendor, this special, very-high-phase viewing geometry lets scientists study ring and atmosphere phenomena not easily seen at a lower phase. 

Since images like this can only be taken while the sun is behind the planet, this beautiful view is all the more precious for its rarity. The last time Cassini captured a view like this was in Sept. 2006, when it captured a mosaic processed to look like natural color, entitled “In Saturn’s Shadow.” In that mosaic, planet Earth put in a special appearance, making “In Saturn’s Shadow” one of the most popular Cassini images to date. Earth does not appear in this mosaic as it is hidden behind the planet. 

Also captured in this image are two of Saturn’s moons: Enceladus and Tethys. Both appear on the left side of the planet, below the rings. Enceladus is closer to the rings; Tethys is below and to the left.

(via NASA - A Splendor Seldom Seen)

sagansense:

Origin Of Life: New Study Spotlights Not Chemistry But How Living Things Store, Process Information

Scientists trying to unravel the mystery of life’s origins have been looking at it the wrong way, a new study argues.

Instead of trying to recreate the chemical building blocks that gave rise to life 3.7 billion years ago, scientists should use key differences in the way that living creatures store and process information, suggests new research detailed today (Dec. 11) in the Journal of the Royal Society Interface.

“In trying to explain how life came to exist, people have been fixated on a problem of chemistry, that bringing life into being is like baking a cake, that we have a set of ingredients and instructions to follow,” said study co-author Paul Davies, a theoretical physicist and astrobiologist at Arizona State University. “That approach is failing to capture the essence of what life is about.”

Living systems are uniquely characterized by two-way flows of information, both from the bottom up and the top down in terms of complexity, the scientists write in the article. For instance, bottom up would move from molecules to cells to whole creatures, while top down would flow the opposite way. The new perspective on life may reframe the way that scientists try to uncover the origin of life and hunt for strange new life forms on other planets.

“Right now, we’re focusing on searching for life that’s identical to us, with the same molecules,” said Chris McKay, an astrobiologist at the NASA Ames Research Center who was not involved in the study. “Their approach potentially lays down a framework that allows us to consider other classes of organic molecules that could be the basis of life.”

Chemical approach
For decades, scientists have tried to recreate the primordial events that gave rise to life on the planet. In the famous Miller-Urey experiments reported in 1953, scientists electrically charged a primordial soup of chemicals that mimicked the chemical makeup of the planet’s early oceans and found that several simple amino acids, the most primitive building blocks of life, formed as a result.

But since then, scientists aren’t much further along in understanding how simple amino acids could have eventually morphed into simple, and then complex, living beings.

Part of the problem is that there isn’t really a good definition of what life is, said Sara Walker, study co-author and an astrobiologist at Arizona State University.

“Usually the way we identify life on Earth is always by having DNA present in the organism,” Walker told LiveScience. “We don’t have a rigorous mathematical way of identifying it.”

Using a chemical definition of life — for instance, requiring DNA — may limit the hunt for extraterrestrial life, and it also may wrongly include nonliving systems, for instance, a petri dish full of self-replicating DNA, she said.

Information processing
Walker’s team created a simple mathematical model to capture the transition from a nonliving to a living-breathing being. According to the researchers, all living things have one property that inanimate objects don’t: Information flows in two directions.

For instance, when a person touches a hot stove, the molecules in his hand sense heat, transmit that information to the brain, and the brain then tells the molecules of the hand to move. Such two-way information flow governs the behavior of simple and complex life forms alike, from the tiniest bacteria to the giant humpback whale. By contrast, if you put a cookie on the stove, the heat may burn the cookie, but the treat won’t do anything to respond.

Another hallmark of living beings is that they have different physical locations for storing and reading information. For instance, the alphabet of letters in DNA carries the instructions for life, but another part of the cell, called the ribosome, must translate those instructions into actions inside the cell, Davies told LiveScience.

(By this definition, computers, which store data on a hard drive and read it off using a central processing unit, would have the hallmarks of life, although that doesn’t mean they are alive per se, Walker said.)

The new model is still in its infancy and doesn’t yet point to new molecules that could have spawned life on other planets. But it lays out the behavior needed for a system needs to be considered living, Walker said.

“This is a manifesto,” said Davies. “It’s a call to arms and a way to say we’ve got to reorient and redefine the subject and look at it in a different way.”