Thursday, November 30, 2017

A Nearby Neutron Star Collision Could Cause Calamity on Earth - Scientific American

From:
A Nearby Neutron Star Collision Could Cause Calamity on Earth - Scientific American:


According to a 2016 study, supernovae occurring as close as 50 light-years from Earth could pose an imminent danger to Earth’s biosphere—humans included. The event would likely shower us in so much high-energy cosmic radiation that it could spark a planetary mass extinction. Researchers have tentatively linked past instances of spiking extinction rates and plummeting biodiversity to postulated astrophysical events, and in at least one case have even found definitive evidence for a nearby supernova as the culprit. Twenty million years ago, a star 325 light-years from Earth exploded, showering the planet in radioactive ironparticles that eventually settled in deep-sea sedimentson the ocean floor. That event, researchers speculate, may have triggered ice ages and altered the course of evolution and human history.
The exact details of past (and future) astrophysical cataclysms’ impact on Earth’s biosphere depend not only on their distance, but also their orientation. A supernova, for instance, can sometimes expel its energy in all directions—meaning it is not always a very targeted phenomenon. Merging black holes are expected to emit scarcely any radiation at all, making them surprisingly benign for any nearby biosphere. A kilonova, however, has different physics at play. Neutron stars are a few dozen kilometers in radius rather than a few million like a typical stars. When these dense objects merge, they tend to produce jets that blast out gamma rays from their poles.
“[W]hat it looks like to us, and the effect it has on us, would depend a lot on whether or not one of the jets was pointed directly at us,” Frank says. Based on its distance and orientation to Earth, a kilonova’s jets would walk the fine line between a spectacular light show and a catastrophic stripping away of the planet’s upper atmosphere. If a jet is pointed directly at us, drastic changes could be in store. And we probably wouldn’t see them coming. A kilonova begins with a burst of gamma rays—incredibly energetic photons that, by definition, move at light-speed, the fastest anything can travel through the universe. Because nothing else can move faster, those photons would strike first, and without warning.
“What [the gamma rays] would do, probably more than anything else, is dissolve the ozone layer,” says Andrew Fruchter, a staff astronomer at the Space Telescope Science Institute. Next, the sky would go blindingly white as the visible light from the kilonova encountered our planet. Trailing far behind the light would be slower-moving material ejected from the kilonova—radioactive particles of heavy elements that, sandblasting the Earth in sufficient numbers, could still pack a lethal punch.
That’s if the kilonova is close, though—within 50 light-years, give or take. At a safer distance, the gamma rays would still singe the ozone layer on the facing hemisphere, but the other side would be shielded by the planet’s bulk. “Most radiation happens very quickly, so half the Earth would be hidden,” Fruchter says. There would still be a momentarily blinding light. For a few weeks, a new star would burn bright in the sky before gradually fading back into obscurity.

Wednesday, November 29, 2017

The Fungus That Turns Ants Into Zombies Is More Diabolical Than We Realized


From:
The Fungus That Turns Ants Into Zombies Is More Diabolical Than We Realized:

Carpenter ants of the Brazilian rain forest have it rough. When one of these insects gets infected by a certain fungus, it turns into a so-called “zombie ant” and is no longer in control of its actions. Manipulated by the parasite, an infected ant will leave the cozy confines of its arboreal home and head to the forest floor—an area more suitable for fungal growth. After parking itself on the underside of a leaf, the zombified ant anchors itself into place by chomping down onto the foliage. This marks the victim’s final act. From here, the fungus continues to grow and fester inside the ant’s body, eventually piercing through the ant’s head and releasing its fungal spores. This entire process, from start to finish, can take upwards of ten agonizing days

Sunday, October 29, 2017

Most Habitable Earth-Like Planets May Be Waterworlds


Most Habitable Earth-Like Planets May Be Waterworlds:

A new study published in The Monthly Notices of the Royal Astronomical Society suggests that most habitable planets are wet. Like, extremely wet. Using computer models, astronomer Fergus Simpson from the Institute of Cosmos Science at the University of Barcelona found that habitable exoplanets, at least simulated ones, tend to be overrun by water, in most cases accounting for 90 percent or more of the total surface area.

Also interesting:

“Larger planets are thought to be more prone to flooding for two reasons,” Simpson told Gizmodo. “One is that if they have the same composition (percentage of water by mass) then their oceans are deeper. The second is that their higher surface gravity makes it harder to have such large surface perturbations [dynamic topological features].”


Tuesday, October 24, 2017

Move over DNA: Six new molecules can carry genes | New Scientist


The ability to copy information from one molecule to another is fundamental to all life. Organisms pass their genes to their descendants, often with small changes, and as a result life can evolve over the generations. Barring a few exceptions, all known organisms use DNA as the information carrier. 
A host of alternative nucleic acids have been made in labs over the years, but no one has made them work like DNA.
This problem has now been cracked. “This unique ability of DNA and RNA to encode information can be implemented in other backbones,” says Philipp Holliger of the MRC Laboratory of Molecular Biology in Cambridge, UK.

Sunday, October 22, 2017

Jupiter Has a Great 'Cold' Spot, Too

Jupiter Has a Great 'Cold' Spot, Too

Maybe some kind of adventure while refueling can be created from this story.

Friday, October 20, 2017

New Theory Suggests Life Can Emerge On Planets Without Water


All quotes from this story, and lots more information here:
New Theory Suggests Life Can Emerge On Planets Without Water

A new theory upends this assumption by suggesting that alien life could thrive on "supercritical carbon dioxide" instead.

Carbon dioxide becomes supercritical when its temperature exceeds 305 degrees Kelvin (about 88 F) and its pressure goes beyond 72.9 the standard atmosphere (atm) at sea level (the kind of pressure you'd find a half-mile beneath the ocean surface).

Fascinatingly, the atmospheric pressure of Venus is about 90 times greater than that of the Earth, with an average temperature of 467 degrees C. About 97% of its atmosphere is carbon dioxide. It's possible, therefore, that the atmosphere of Venus is a SCF. And indeed, the researchers speculate that organic remnants of life could still be preserved in such a fluid.

Also an article in Space: http://www.foxnews.com/science/2014/11/16/alien-life-could-thrive-on-supercritical-co2-instead-water/

And the original research: http://www.mdpi.com/2075-1729/4/3/331



Sunday, October 15, 2017

Massive Lava Waves Detected on Jupiter’s Moon Io


Thanks to a rare orbital alignment between Europa and Io, an international team of researchers has identified and tracked a pair of lava waves as they coursed around Loki Patera, which is larger than Lake Ontario, and with a surface area of 8,300 square miles (21,500 square km). The most likely explanation for this apparently periodic wave action is an overturning circulation pattern, in which cool surface crust slowly thickens and sinks, pulling nearby crust along with it in a wave that spreads across the surface. 


More Info:
Massive Lava Waves Detected on Jupiter’s Moon Io