Defying its reputation as aloof, this tortoiseshell cat was labelled “the friendliest cat we met” by Flickr user benjgibbs

As much as we might not like to admit it, humans make snap judgments based on appearances all the time. And that’s true even when it comes to cats. White Persians are snooty. Black cats are evil or unlucky. Some shelters even suspend adoptions of black cats and white cats around Halloween in fear of what misguided people might do with the kitties.

In a new study published in Anthrozoos, researchers from California State University and the New College of Florida set out to discover our hidden kitty biases with an Internet-based survey of nearly 200 people. They asked the participants to associate 10 personality terms (active, aloof, bold, calm, friendly, intolerant, shy, stubborn, tolerant and trainable) with five cat colors–orange, tri-colored (tortoiseshells and calico cats), white, black and bi-colored (white and anything else).

Some trends appeared in the data. Orange kitties were perceived as friendly and rated low in the aloof and shy categories. (They were also considered more trainable than were white cats, although the idea that anyone considers a cat trainable is kind of funny. Or am I betraying my own bias here?) Tri-colored cats rated high in aloofness and intolerance, and white cats were also considered aloof, as well as shy and calm. And bi-colored cats–which could have been any color, really, in the participants’ minds–were thought to be friendly. The data for black cats, however, was a bit muddier and no clear trends emerged.

Despite people’s perceptions that there are links between coat color and how a cat will behave, there is little hard evidence that such a connection is real. “But there are serious repercussions for cats if people believe that some cat colors are friendlier than others,” Mikel Delgado, lead author of the study and a doctoral student in psychology at the University of California, Berkeley, said in a statement.

That’s because when people are choosing a cat, they may make assumptions based on coat color about how that cat will behave in the home. But when they take the kitty home and he isn’t as friendly or cuddly or sedentary as they had hoped, the cat may be returned to the shelter. At least a million cats end up in shelters each year; many of them are euthanized.

And these biases have repercussions for cats of certain colors. A 2002 study in the Journal of Applied Animal Welfare Science, for example, found that black cats and brown cats were the least likely to be adopted. Dark cats were also more likely to euthanized. And despite there being little genetic evidence that the genes that guide the coloring and patterning on a cat’s coat also influence it’s behavior, the study found that people frequently believed that tortoiseshells had too much attitude (or “tortitude”), which may explain why they don’t get adopted quickly or get returned to the shelter.

But it’s difficult to cut through people’s biases. So shelters will have to work extra hard to educate prospective kitty adopters about cats and cat behavior. “You can’t judge a cat by its color,” Berkeley East Bay Humane Society cat coordinator Cathy Marden said in a statement. “If someone comes in to adopt, we encourage them to spend time with all the cats, because it’s the personality of that cat–not the color–that will let you know if the animal’s the right fit for you.”

And if a black cat crosses your path this week, don’t get frightened. He’s no more likely to be evil than the cat you have at home.

A four-year-old girl reenacts the marshmallow test (Credit: J. Adam Fenster / University of Rochester)

When I wrote about the marshmallow test several years ago, it seemed so simple:

A child was given a marshmallow and told he could either ring a bell to summon the researcher and get to eat the marshmallow right away or wait a few minutes until the researcher returned, at which time the child would be given two marshmallows. It’s a simple test of self control, but only about a third of kids that age will wait for the second marshmallow. What’s more interesting, though, is that success on that test correlates pretty well with success later in life. The children who can’t wait grow up to have lower S.A.T. scores, higher body mass indexes, problems with drugs and trouble paying attention.

The initial finding hasn’t been overturned, but a new study in the journal Cognition is adding a layer of complexity to the test with the finding that whether the child perceives the researcher as trustworthy matters.

“Our results definitely temper the popular perception that marshmallow-like tasks are very powerful diagnostics for self-control capacity,” Celeste Kidd, a doctoral candidate in brain and cognitive sciences at the University of Rochester and the study’s lead author, said in a statement.

Kidd and her colleagues started their experiment by adding a step before giving their group of 28 three- to five-year-old children the marshmallow test: Similar to the marshmallow test, the children were given an art task, with a researching placing before a child either a well-worn set of crayons or a small sticker. The children were promised a better art supply (new crayons or better stickers) if they waited for the researcher to come back. With half of the children, though, the researcher didn’t follow up on that promise, telling the kid that better supplies were unavailable.

And then the researcher administered the marshmallow test.

Children who had been primed to believe that the researcher was reliable waited an average of 12 minutes before eating the marshmallow, but those in the “unreliable” group waited only three minutes. What’s more, nine out of 14 children in the “reliable” group were able to wait the full 15 minutes for the researcher to return, while only one kid in the unreliable group was able to wait that long.

“Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay,” Kidd said. Self control isn’t so important, it seems, if you don’t think there’s anything worth controlling yourself for.

Kidd got interested in the test after volunteering at a homeless shelter. “There were lots of kids staying there with their families. Everyone shared one big area, so keeping personal possessions safe was difficult,” Kidd said. “When one child got a toy or treat, there was a real risk of a bigger, faster kid taking it away. I read about these studies and I thought, ‘All of these kids would eat the marshmallow right away.’ ”

The study doesn’t invalidate the marshmallow test–willpower is still important–but it does mean that people shouldn’t look at kids who fail the test as being instantly doomed to failure. Instead, parents of kids who appear to lack self control might want to look more closely at why they would eat the marshmallow–is it because they can’t wait or because they can’t trust that the next marshmallow will appear?

A genetic mutation determines whether a tabby cat is a mackerel (top row) or blotched (bottom row). (Image courtesy of Helmi Flick)

Tabby may be a colloquial term for a female kitty, but it’s more properly the name for the common stripey pattern on a domestic cat’s coat. Those tabby markings come in two main varieties: proper vertical stripes of dark on a light background, known as the mackerel pattern, and a blotched variety consisting of less-organized, dark whorls. Now scientists from Stanford University and elsewhere have identified the gene that determines whether a tabby is mackerel or blotched and found that the same gene also can make a cheetah a king. The study appears in today’s issue of Science.

“We were motivated by a basic question: How do periodic patterns like stripes and spots in mammals arise?” study co-author Gregory Barsh, an investigator at HudsonAlpha and a Stanford geneticist, said in a press release. “Until now, there’s been no obvious biological explanation for cheetah spots or the stripes on tigers, zebras or even the ordinary house cat.”

Barsh and his colleagues examined DNA taken from feral kitties in Northern California that were captured, sterilized and released (a common practice employed to control the size of feral cat populations) and from tissue samples collected by the City of Huntsville Animal Services group. All the mackerel tabbies they studied had a normal version of a gene the researchers named Transmembrane Aminopeptidase Q (Taqpep) while all the blotched tabbies had a mutated form of the gene.

The Taqpep gene establishes the pattern of a cat’s coat while a kitty is still in the womb, likely by determining the level of expression of another gene–Endothelin3 (Edn3)–that drives the shade produced by a hair cell (lots of Edn3 results in darker hair). The form of the pattern is actually established out of a random interaction of chemicals that ends up producing something that looks non-random–British mathematician Alan Turing first proposed this theory in 1952, and it was later simulated in computer models and earlier this year scientists discovered the chemicals in question.

Still to be determined, though, is why some domestic cats don’t have any pattern at all despite the status of their Taqpep gene. (On a side note, blotched tabbies are sometimes called “classic” tabbies but not because they’re more common. The blotched pattern is a more recent mutation; the original wild ancestors of domestic kitties were mackerels similar to Old World wild cats of today.)

But domestic cats aren’t the only cats that can vary in coat pattern, of course. Most cheetahs, for example, are the common spotted variety, but a few rare cats are known as king cheetahs, and these sub-Saharan kitties have dark stripes running along their backs (see below). When the researchers examined skin and blood samples taken from captive and wild cheetahs from South Africa and Namibia, they found that not only did the cats have the same Taqpep gene as domestic kitties, but also the gene worked in a similar way on the wild cats’ coats. A normal Taqpep gene produced the regular spotted cats but a mutated Taqpep merged the spots into stripes, just as the gene had merged the tabby stripes into blotches.

Though scientists cannot yet explain how the zebra got its stripes, at least now they can explain how the king cheetah got his.

The difference between a normal spotted cheetah (left) and a rare king cheetah (right) is a mutation in a single gene. (Image courtesy of Greg Barsh, from the Ann van Dyk cheetah preserve)

Astronomers identified a fifth moon orbiting Pluto (Illustration Credit: NASA, ESA, and L. Frattare (STScI); Science Credit: NASA, ESA, and M. Showalter (SETI Institute))

Last week, astronomers identified a fifth moon–named P5 for now–orbiting Pluto in images taken by the Hubble Space Telescope. The moon is a mere 6 to 15 miles in diameter and orbits in a 58,000-mile-diameter circular orbit around the dwarf planet. “The [five] moons form a series of neatly nested orbits, a bit like Russian dolls,” said team lead Mark Showalter of the SETI Institute.

The finding of P5 has some again questioning Pluto’s demotion to dwarf planet status. New Scientist reports:

The discovery provides some ammunition for those upset at Pluto’s demotion from the planetary ranks. “If you are important enough to have acquired five satellites, you are a planet!” says Kevin Baines, a planetary scientist at NASA’s Jet Propulsion Laboratory.

But having or not having moons is not part of the qualifications for planet status. In 2006, the International Astronomical Union defined a planet as having three characteristics:

1. It orbits the Sun.
2. It has has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape.
3. It has cleared the neighborhood around its orbit.

Unfortunately for Pluto fans, Pluto fails on count three, and the IAU does not plan to revisit the issue anytime soon. And so it seems that Pluto is doomed to stay a dwarf planet for the time being.

The discovery of P5, however, does have important implications for the New Horizons spacecraft headed towards Pluto and scheduled to rendezvous in July 2015. “The inventory of the Pluto system we’re taking now with Hubble will help the New Horizons team design a safer trajectory for the spacecraft,” said New Horizons’ principal investigator Alan Stern of the Southwest Research Institute. There is real worry that New Horizons could be destroyed if it runs into even a small piece of debris as it zooms past Pluto at 30,000 miles per hour.

As for what P5 (and P4, discovered last year) will eventually be named, that’s still up in the air, although Showalter told New Scientist that after he had finished his search of the Hubble data and found all of Pluto’s moons he would suggest names in the Hades/underworld theme that gave us Charon, Hydra and Nix. I came up with a few options for moon names last year on this blog (Erberus, Styx and Hypnos–in our poll, our readers liked Styx best), but I think Showalter might be running out of options in his preferred theme and will have to do some real digging into classical history once he gets to P7 and beyond.

King penguins are the second largest species of penguin (Credit: V.Viblanc/IPEV)

In 1961, a group of scientists set up a permanent camp on Possession Island, a bit of land located in the Crozet Archipelago, about halfway between Madagascar and Antarctica in the Indian Ocean. Their goal was a long-term study of king penguins (Aptenodytes patagonicus), and scientists have continued that study for more than 50 years, sometimes accompanied by a small number of tourists. The penguins appear to be habituated to the presence of humans, but a new study in BMC Ecology finds that even this limited human contact may be negatively affecting them.

A team of researchers from France and Switzerland compared 15 king penguins from the areas regularly disturbed by scientists and tourists with 18 birds that bred in an undisturbed area, recording the penguins’ heart rates (an indicator of stress) in response to three potential human stressors–loud noise, approaches by humans (similar to what would happen when a scientist or tourist would observe the birds) and capture (a rare but necessary technique used when studying the penguins).

With both loud noise and human approach, the penguins from the disturbed area were far less stressed than their counterparts from the undisturbed area. All the birds, however, found capture to be a stressful experience.

Is this evidence that the penguins from the regularly disturbed are habituated to humans? Maybe, say the researchers, but maybe not. While it’s possible that these penguins have grown used to the presence of humans in their breeding area–though not capture, since that is a rare occurrence–the regular disturbance may be contributing to the selection of specific phenotypes, those that are most suited to handle this kind of stress. Over time, the population would evolve to handle this disturbance better and better. That may seem like a good thing, but the resulting population, the scientists say, may be less able to cope with environmental change.

This is hardly the first time that researchers have found that their methods have had unintended consequences for the animals they study. A penguin study published last year, for example, found that the use of flipper bands resulted in lower survival rates for the birds; it was just the latest in four decades of research that had been hinting that banding penguins was bad for the birds. But this latest study is another reminder to the science community that they can easily become one of the anthropogenic disturbances that affect the animals they are studying.

“A central question for ecologists is the extent to which anthropogenic disturbances [such as tourism] might impact wildlife and affect the systems under study,” lead author Vincent Viblanc of the Université de Strasbourg said in a statement. “One of the major pitfalls of such research is in forgetting that, from the perspective of the wildlife studied, tourism and scientific research are not two worlds apart.”

Sthenurus, an extinct giant kangaroo (drawing by Peter Murray, copyright Science/AAAS)

While in Sydney earlier this year, I stopped in at Australia Museum, the city’s equivalent of the Smithsonian Museum of Natural History, and learned a bit about the continent’s extinct megafauna. Australia didn’t have mammoths or saber-toothed tigers, but there were giant marsupials, such as the bear-like wombat Diprotodon and the thylacine (a.k.a. the Tasmanian tiger). On a tour of the museum, I came across a display that said that most of these mega-mammals had gone extinct tens of thousands of years before, the victims of either changes to the climate that led to drier conditions or human impacts, including hunting and landscape burning. The thylacine was the one exception to the megafauna story–it hung on until British colonization and then it was hunted to extinction.

But this story was incomplete it seems, though the museum holds no blame. A couple weeks after I returned to Washington, Science published a study addressing this very issue (for all the megafauna but the thylacine, but we’ll get to the tigers in a moment). Susan Rule of Australian National University and her colleagues analyzed pollen and charcoal in two sediment cores taken from a lake in northeast Australia to create a record of vegetation, fire and climate changes over the past 130,000 years. They also looked at spores of the fungus Sporormiella, which is found in dung and is most prevalent when there are large herbivores in the area.

With this record, Rule and her colleagues determined that there were two great climate upsets 120,000 and 75,000 years ago, but the megafauna had no problems surviving those times. However, between about 38,000 and 43,000 years ago, Sporormiella spores decreased in the record, likely reflecting the disappearance of large herbivores during that time, which correlates with the arrival of humans on the Australian continent. Following the megafauna disappearance, the cores displayed an increase in charcoal, an indicator of a greater frequency of wildfires. “The fire increase that followed megafaunal decline could have been anthropogenic, but [the record suggests] instead that relaxation of herbivory directly caused increased fire, presumably by allowing the accumulation of fine fuel,” the authors write. The lack of herbivores in the Australian ecosystem led to changes in the types of plants growing there–rainforests were replaced by sclerophyll vegetation that burns more readily.

So, the likely story is that humans came to Australia around 40,000 years ago, hunted mega-mammals to extinction, which spurred changes to the vegetation growing in the area and resulted in an increase in wildfires.

But what about the thylacine? Only one species, Thylacinus cynocephalus, survived to more recent times, though it disappeared from much of New Guinea and mainland Australia by about 2,000 years ago, likely due to competition with humans and, maybe, dingoes. A few pockets of the species were reported in New South Wales and South Australia in the 1830s but they were soon extirpated. The thylacine’s last holdout was the island of Tasmania, but locals quickly hunted them to extinction, certain the thylacines were responsible for killing sheep. The last known thylacine in the wild was killed in 1930, and the last one in captivity died in 1936. They were declared extinct in 1986.

Recent research has helped to flesh out the thylacine’s story: A study published last year in the Journal of Zoology found that the thylacine’s jaw was too weak to take down an animal as large as a sheep–the animals had been hunted to extinction for crimes they were biologically unable to commit. Though is appears that the hunting may have simply hastened the inevitable. Another study, published in April in PLoS ONE, found that the thylacine had low genetic diversity, which would have made the species more susceptible to disease and further declines, possible leading to extinction.

But is the thylacine really gone? Tasmanians occasionally claim to have seen a thylacine or found evidence of one in the area–in January, for example, two brothers found a skull they claimed came from a thylacine–but none of these sightings has ever panned out with real evidence, such as a clear photo or video. Zoologist Jeremy Austin of the University of Adelaide tested DNA in alleged thylacine droppings collected between 1910 and 2010 but none were actually from a thylacine.

Australian Museum scientists had planned to attempt cloning a thylacine, but those efforts were abandoned years ago. So, for now at least, all of Australia’s mega-mammals will stay extinct.

One of the hundreds of trees lost to Friday night’s derecho (courtesy of flickr user woodleywonderworks).

The Washington, DC area has seen its fair share of destructive storms–we get hurricanes, tornadoes and even the rare snowpocalypse. But on Friday night we got hit with another type of storm–one that I’d never heard of–called a derecho (pronounced ”deh-REY-cho”).

The storm swept through the area late Friday evening, bringing an incredible amount of thunder and lightning, winds up to 80 mph and sheets of rain. By morning, hundreds of trees had been blown down, millions were left without power and several people were dead. Netflix, Pinterest and Instagram had all been taken down by Amazon server outages caused by the storm. The Smithsonian Folklife Festival had to shut down for a day to clean up the mess. We were all left wondering, “what in the world had happened?”

Friday’s derecho originated near Chicago and raced southeast towards Washington, DC (courtesy of NOAA)

The stifling heat wave that we’d been suffering through, which had stretched from the Midwest through the mid-Atlantic to the Southeastern United States and brought temperatures in excess of 100 degrees Fahrenheit, was to blame for the fast-moving band of thunderstorms. The Capitol Weather Gang explains:

As this stifling air bubbled northward, clashing with the weather front draped from near Chicago to just north of D.C., thunderstorms erupted. They grew in coverage and intensity as they raced southeast, powered by the roaring upper level winds and fueled by the record-setting heat and oppressive humidity in their path.

The coverage and availability of this heat energy was vast, sustaining the storms on their 600 mile northwest to southeast traverse. The storms continually ingested the hot, humid air and expelled it in violent downdrafts – crashing into the ground at high speeds and spreading out, sometimes accelerating further.

Though unfamiliar to those of us here on the East Coast, derechos occur more commonly in the Corn Belt, which runs from Mississippi into the Ohio Valley, but even there they are relatively infrequent. They can wreak their havoc at any time of the year but are most likely to occur during May, June and July. Derechos get their starts in curved bands of thunderstorms called “bow echoes,” which are perhaps better known for their ability to spawn tornadoes. But instead of rotating cells of winds, derechos blow and travel in straight lines.

Derechos have a long history here in the United States. The term “derecho” was coined by University of Iowa physics professor Gustavus Hinrichs in an 1888 paper in the American Meteorological Journal in which he illustrated the path of such a storm that had crossed over Iowa on July 31, 1877. The storm’s straight path across the state gave Hinrichs the inspiration for the storm’s name–”derecho” means “straight” in Spanish. But path alone isn’t quite enough for a storm to qualify as a derecho; wind speeds must also reach a minimum of 57 mph.

Given that derechos are associated with warmer weather, could they become more common as the United States heats up due to climate change? Tom Kines, senior meteorologist at AccuWeather.com, told the Guardian: “If indeed we are seeing global warming, then it will certainly increase the risk of something like this happening again.”

Photinus pyralis, a species of firefly found in the eastern United States (via Terry Priest / wikimedia commons)

What’s more magical than a firefly light show on a warm summer night? Just remember that if you catch fireflies, you can keep them in a jar (with a lid punched to let in air and a moistened paper towel on the bottom) for only a day or two before you need to set them free.

(1) There are more than 2,000 species of fireflies, a type of beetle. Despite their name, only some species produce adults that glow. Fireflies in the western United States, for example, lack the ability to produce light.

(2) Males that do glow use their flash to attract females. Each species has its own pattern of light flashing.

(3) In some places at some times, fireflies synchronize their flashing.

(4) Firefly light can be yellow, green or orange.

(5) Firefly larvae may glow, even some that live underground or under water. They use the light to communicate to predators that they aren’t tasty (they produce unpalatable, defensive steroids for protection).

(6) Larvae are carnivorous and particularly enjoy snails. Adult fireflies usually live off of nectar and pollen, but some don’t feed at all.

(7) A few firefly species are also carnivorous as adults. They don’t eat snails, though—they eat fireflies of other genera.

(8) Fireflies are among the many species that are bioluminescent, meaning that they can produce their own light.

(9) A chemical reaction within the firefly’s light organ produces the light—oxygen combines with calcium, adenosine triphosphate (ATP—the energy-carrying molecule of all cells) and a chemical called luciferin, when an enzyme called luciferase is present.

(10) The light is the most efficient light in the world. Nearly 100 One hundred percent of the energy in the chemical reaction is emitted as light.

(11) Luciferase has proven to be a useful chemical in scientific research, food safety testing and forensic tests. It can be used to detect levels of ATP in cells, for example.

(12) When luciferase was first discovered, the only way to obtain the chemical was from fireflies themselves. Today, synthetic luciferase is available, but some companies still harvest fireflies, which may be contributing to their decline.

(13) Other factors that may be contributing to firefly decline include light pollution and habitat destruction—if a field where fireflies live is paved over, the fireflies don’t migrate to another field, they just disappear forever.

(14) Observing fireflies in your backyard can help scientists learn more about these insects and why they’re disappearing.

A cheetah in full stride (courtesy of flickr user ShootNFish)

If you could put a wild cheetah up against a greyhound in a race, the cheetah would win, no problem. After all, the cheetah’s top recorded speed is 65 mph, and the cats are thought to be capable of much more. Greyhounds top out around 40 mph, fast enough to provide a show for bettors at the racetrack, but no match for the cats.

But why should that be? Cheetahs and greyhounds are about the same size, and they’ve got similar body shapes. In a new study in the Journal of Experimental Biology, biologists from the University of London made a series of measurements of cheetahs from a zoo in England and a cheetah center in South Africa and greyhounds that had retired from their racing careers in England to figure out why the cats are faster. The animals were filmed with high-speed cameras as they raced along a 100-yard track chasing a mechanical lure. Some of them were also trained to run across a force plate.

The cats and dogs had several differences in how they ran–at any given speed, the cheetahs used longer strides and fewer of them than the greyhounds. The cats also supported their weight differently, putting more of it on their hindlimbs, which may enhance their grip and allow for better acceleration and maneuvering while leaving their forelimbs free to capture prey.

But the scientists can’t say definitively that they’ve found out why cheetahs are faster because these cheetahs weren’t. They topped out at 39.8 mph, never reaching anywhere close to 65 mph and not even running faster than the greyhounds in the study. “They have lived in a zoo for several generations and have never had to run to catch food. They have probably never learned to run particularly,” says Alan Wilson, one of the project scientists. The greyhounds, meanwhile, were trained for races, encouraged to develop to run at the fastest speeds possible.

Io9 called this a failed experiment, since the captive cheetahs were so slow. But I would argue otherwise–the researchers identified plenty of differences between the two animals that may explain the cheetah’s edge, which was the point of the study. That said, it would be nice if they could try this with with wild cheetahs, which Wilson says they will try. Though I suspect that wrangling one of those speedy cats will provide new challenges to the researchers.

No one is going to Mars until scientists figure out how to shield travelers from deadly radiation. (Source: NASA/NSSDC)

Would you go on a mission to Mars? The Dutch startup company Mars One is planning to establish the first Mars colony in 2023, starting with four individuals and adding more people every two years, funded by turning the whole endeavor into a reality TV show.

It’s just the latest plan to colonize the Red Planet, but I’m doubtful it will happen. There’s the expense, for sure, and the trials of trying to convince anyone to go on a one-way journey with just a few other strangers (what if you don’t get along? It’s not like you can leave). And then there’s the radiation problem.

Out in space, there are gamma rays from black holes, high-energy protons from the Sun, and cosmic rays from exploding stars. Earth’s atmosphere largely protects us from these types of radiation, but that wouldn’t help anyone traveling to Mars. They would be exposed to dangers that include neurological problems, loss of fertility and an increased risk of cancer.

NASA scientists calculated in 2001 that a 1,000-day Mars mission would increase the risk of cancer somewhere between 1 and 19 percent. If the risk is on the lower end, then the outlook for Mars might be pretty good, but if it’s higher, then NASA, at least, wouldn’t send people (there’s no telling what a reality TV show might do). A 2005 study found even more to worry about—the radiation would be high enough to cause cancer in 10 percent of men and 17 percent of women aged 25 to 34 if they were to go to Mars and back.

The easy solution would seem to be to shield the vessel that carries the humans to Mars, but no one has figured out how to do that. When the thin aluminum currently used to build spacecraft is hit with cosmic rays, it generates secondary radiation that is even more deadly. Plastic might work—the shields on the International Space Station are made of plastic—but it’s not 100-percent effective. One scientist has suggested using asteroids to shield a vessel traveling between Earth and Mars. But somehow I don’t think Mars One is going to make that one work within a decade.

Or they could just send old people—a solution proposed a couple of years ago by Dirk Schulze-Makuch of Washington State University and Paul Davies of Arizona State University. “This is not a suicide mission. The astronauts would go to Mars with the intention of staying for the rest of their lives, as trailblazers of a permanent human Mars colony,” Schulze-Makuch and Davies wrote in the Journal of Cosmology. Loss of fertility wouldn’t be an issue for older astronauts and the radiation wouldn’t increase their lifetime cancer risk too much (since they’re already near the end of their lives).

That may be a solution more suited to NASA than Mars One, however, since television casting departments would probably want someone more like Snooki than Snooki’s grandma.

Editor’s note: In other Mars news, NASA is preparing for the August 5 landing of its massive unmanned science laboratory, Curiosity. The seven minutes between when the rover hits the top of the atmosphere and when it touches ground are the riskiest moments of the whole mission. The video below shows a few of the hundreds of things that need to go just right:

Flying foxes roost in the trees in Sydney's Royal Botanic Gardens in 2008. (Photo by Sarah Zielinski)

In downtown Sydney, just behind the iconic Opera House, lies the Royal Botanic Garden, 75 acres of flowers, trees and grassy areas first established in 1816 on the site of Australia’s first farm, Farm Cove. The gardens are a place for tourists and the people of Sydney to explore and enjoy, and they’re also a site for conservation research. Because this is one of the biggest green spaces in the city, the gardens are home to plenty of wildlife, including flocks of cockatoos and bats with wingspans a yard wide.

While the cockatoos can be annoying (especially if you’re stupid enough to feed them), the bats—called grey-headed flying foxes—have become a real problem, at least in the eyes of garden management. These mammals are herbivores and leave the human visitors largely alone (though they can at times be incredibly creepy). However, they damage the garden because they defoliate trees. In the more than 20 years since the bats took up residence in the gardens, they’ve killed 28 mature trees, 30 palms and many other plants and damaged another 300. Most worrisome, they settled in the Palm Grove, site of many of the oldest trees in the garden, including historic, exotic species collected from places such as Malaysia and New Guinea. So several years ago the management of the garden decided that the flying foxes had to go.

But grey-headed flying foxes are a species on the decline (IUCN lists them as vulnerable) and protected in Australia. They’ve lost foraging and roosting habitat in many places, and commercial fruit tree growers consider them a pest and kill them (either illegally or with permission from the government).

The Botanic Garden couldn’t kill the bats, though, so they came up with a plan to force them out. They would play recorded noise in late autumn and early winter just before dawn—making it difficult for them to sleep peacefully after a night of foraging—and around sunset, giving them an early wake-up call. The idea is that the bats would be so annoyed that they would decide to roost somewhere else. Wouldn’t you leave a hotel if the people in the neighboring room played loud music when you were trying to fall asleep and you kept getting 3 a.m. wake-up calls?

After several reviews and many delays, the Botanic Garden finally implemented its plan this month. By last week, there were only about 10 bats left in the gardens. The rest appear to have fled a couple of miles south to Centennial Park. The Botanic Gardens will now turn its efforts to restoring the areas damaged by the flying foxes.

The story may not end there, however. The recorded noises will be played only until sometime in July. After that, it would be too disturbing for pregnant flying foxes, who could abort due to the stress, or for new mothers who might be separated from their babies. But flying foxes move seasonally, and come September or October, bats from outside the area could decide the gardens look like a great home.

Garden management is hopeful that the plan will work. After all, the Royal Botanic Gardens Melbourne successfully removed their own grey-headed flying fox population in 2003 using similar methods. Those bats can now be found in nearby Yarra Bend Park.

But was the removal of the flying foxes from the Sydney gardens really necessary? When I first heard of this plan, shortly before my latest trip to Sydney in March, I was sad to hear that the bats would soon be gone. They were one of my favorite memories from my first trip there—looking up on a beautiful fall day to see hundreds of these little Draculas hanging above me. While I was in Sydney this year, I met with Tim Cary, a bat researcher at Macquarie University. He made a good case for why stressing out these animals was akin to torture and contended that the plan was doomed to fail. (Cary suggested tenting the Palm Grove with netting to keep the bats out.)

I also met with Mark Salvio, director of the Royal Botanic Garden, and we spoke at length about the level of destruction, the plans to get rid of the flying foxes and the levels of review and restructuring that the plans had gone through over the years. This isn’t something that is being done without any consideration for the consequences to the grey-headed flying fox species. And as much as I enjoyed the bats during my visits, I could understand that the Garden had placed its foliage as a higher priority–that’s why it exists, to preserve the gardens and their history. (After all, I doubt that the Smithsonian Institution would let its collections be destroyed by, say, insects in the warehouse, even if those insects were an endangered species.)

Did Sydney’s Royal Botanic Garden make the right choice? Is stressing the bats a truly horrible thing to do? Will it even work? We’ll have to wait and see on that last question. As for the other two, I know where Cary stands. Where do you?

Some scientists have suggested the weight of water in the lake created by the Zipingpu Dam in China triggered the 2008 Sichuan earthquake (courtesy of flickr user TaylorMiles)

Update on April 16, 2012: A new study by the U.S. Geological Survey to be presented Wednesday indicates that the “remarkable increase” in earthquakes in the continental United States that rate greater than 3 on the Richter Magnitude Scale is “almost certainly manmade.” The authors note that although it is unclear whether new hydrofracturing (a.k.a. fracking) techniques to recover natural gas are to blame, “the increase in seismicity coincides with the injection of wastewater in deep disposal wells.” —Joseph Stromberg

On Saturday, a magnitude 4.0 earthquake shook eastern Ohio, a week after a smaller temblor in the region worried officials so badly that they halted work on a fluid-injection well in Youngstown.

This wasn’t the first case in which the injection of fluids into the earth has been linked with earthquakes. In April, for example, the English seaside resort town of Blackpool shook from a magnitude 2.3 earthquake, one of several quakes now known to have been caused by hydraulic fracturing (or “fracking,” which involves pumping large amounts of fluid into the ground to release natural gas) in the area. The link has been known for decades—a series of quakes in the Denver, Colorado, region in 1967 was caused by fluid injection.

The phenomenon is so well known that Arthur McGarr, a geologist at the U.S. Geological Survey in Menlo Park, California, has developed a method to predict the highest magnitude of an earthquake that could be produced by hydraulic fracturing, carbon sequestration, geothermal power generation or any method that involves injecting fluid deep into the earth. Though the method doesn’t allow scientists to predict the likelihood that such a quake would occur, it will let engineers better plan for worst-case scenarios, McGarr told Nature.

Hydraulic fracturing naturally causes small tremors, but bigger quakes may occur if the liquid migrates beyond the area where it’s injected. The New York Times reports:

The larger earthquakes near Blackpool were thought to be caused the same way that quakes could be set off from disposal wells—by migration of the fluid into rock formations below the shale. Seismologists say that these deeper, older rocks, collectively referred to as the “basement,” are littered with faults that, although under stress, have reached equilibrium over hundreds of millions of years.

“There are plenty of faults,” said Leonardo Seeber, a seismologist with the Lamont-Doherty Earth Observatory. “Conservatively, one should assume that no matter where you drill, the basement is going to have faults that could rupture.”

Earthquakes caused by fracking are of particular interest right now because the number of wells, particularly in the United States, has been skyrocketing (along with reports of nasty environmental consequences, such as flammable water). But this is only one way that humans are causing the earth to quake. Mining (taking weight from the earth), creating lakes with dams (adding weight on top of the earth) and extracting oil and gas from the earth have caused at least 200 earthquakes in the last 160 years, Columbia University earthquake scientist Christian Klose told Popular Science.

Klose’s research has demonstrated that coal mining was responsible for Australia’s most damaging earthquake in recent memory, the magnitude 5.6 Newcastle earthquake of 1989. And in 2009, he was one of several scientists who suggested that the magnitude 7.9 earthquake in China’s Sichuan Province in 2008, which left 80,000 dead, could have have been triggered by the Zipingpu Dam. (That wasn’t the first time a dam was linked to an earthquake—Hoover Dam shook frequently as Lake Mead filled.)

It can be easy to look at our planet and think we’re too small to really do much damage, but the damage we can do can have severe consequences for ourselves. ”In the past, people never thought that human activity could have such a big impact,” Klose told Wired, “but it can.”

The first Death Star from Star Wars (via Wookieepedia)

Obi-Wan: That’s no moon. It’s a space station.

That space station was the Empire’s first Death Star in Star Wars: A New Hope. Obi-Wan and company had just bounced through a debris field, the remnants of the planet Alderaan. Such an act of destruction would seem impossible to us–it seemed so to many of the movie’s characters until it happened. But perhaps not, say three students at the University of Leicester in England who last year published a study on the subject in their university’s undergraduate physics and astronomy journal.

The study’s authors start off by making some simple assumptions: The planet being fired upon doesn’t have some sort of protection, like a shield generator. And it’s about the size of Earth but solid through and through (Earth isn’t solid, but the planet’s layers would have significantly complicated the math here). They then calculate the planet’s gravitational binding energy, which is the amount of energy required to pull apart an object. Using the mass and radius of the planet, they calculate that destruction of the object would require 2.25 x 10³² joules. (One joule is equal to the amount of energy required to lift an apple one meter. 10³² joules is a lot of apples.)

The energy output of the Death Star isn’t given directly in the movie, but the space station was said to have had a “hypermatter” reactor that had the energy output of several main-sequence stars. For an example of a main-sequence star, the authors look to the Sun, which puts out 3 x 10²⁶ joules per second, and they conclude that the Death Star could “easily afford to output [the energy required for an Earth-like planet's destruction] due to to its tremendous power source.”

It would be a different story, though, if the planet scheduled for destruction had been more like Jupiter than Earth. The gravitational binding energy of Jupiter is 1,000 times that of the Earth-like planet in the study. “To destroy a planet like Jupiter [the space station] would probably have to divert all remaining power from all essential systems and life support, which is not necessarily possible.”

Of course, that assumes that the Emperor wouldn’t be willing to sacrifice a space station full of people to wipe out his enemies. And considering that he was just fine with wiping out whole planets, I’m not sure I’d take that bet.

A sample of highly enriched uranium (via wikimedia commons)

Enriched uranium is back in the news with a report that Iran has begun creating the stuff at a heavily fortified site in the north of that country. But what is enriched uranium?

Uranium is element 92 on the periodic table–every molecule has 92 protons in its nucleus. The number of neutrons can vary, and that’s the difference between the three isotopes of uranium that we find here on Earth. Uranium-238 (92 protons plus 146 neutrons) is the most abundant form, and about 99.3 percent of all uranium is U-238. The rest is U-235 (0.7 percent), with a trace amount of U-234.

Uranium has a bad reputation (it is radioactive, after all), but U-238 has a very long half-life, meaning that it can be handled fairly safely as long as precautions are taken (as seen in the video below). More importantly here, though, U-238 isn’t fissile–it can’t start a nuclear reaction and sustain it.

U-235, however, is fissile; it can start a nuclear reaction and sustain it. But that 0.7 percent in naturally occurring uranium isn’t enough to make a bomb or even a nuclear reactor for a power plant. A power plant requires uranium with three to four percent U-235 (this is known as low-enriched or reactor-grade uranium), and a bomb needs uranium with a whopping 90 percent U-235 (highly enriched uranium).

Uranium enrichment, then, is the process by which a sample of uranium has its proportion of U-235 increased.

The first people to figure out how to do this were the scientists of the Manhattan Project during World War II. They came up with four methods to separate the U-235 from uranium ore: gaseous diffusion, electromagnetic separation, liquid thermal diffusion and centrifugation, though at the time they deemed centrifugation not practical for large-scale enrichment.

The most common methods for enriching uranium today are centrifugation (decades of development have made this method more efficient than it was during WWII) and gaseous diffusion. And other methods are being developed, including several based on laser techniques.

Highly enriched uranium, the type used in bombs, is expensive and difficult to create, which is why it remains a barrier, though not an insurmountable one, for countries wishing to develop nuclear weapons. And once a nation develops the capability for enriching uranium beyond reactor grade (Iran has reportedly begun to produce uranium enriched up to 20 percent), the path to weapons-grade uranium is significantly sped up.

Find out more about nuclear concerns in Iran from Arms Control Wonk, the Carnegie Endowment for International Peace and ISIS NuclearIran, from the Institute for Science and International Security.

And learn more about the element uranium, including depleted uranium, in this selection from the Periodic Table of Videos:

Mauna Loa (as seen from nearby Mauna Kea) is tall enough to have snow, at least when the volcano isn't erupting (courtesy of flickr user superfluity)

If asked to name the tallest mountain on Earth, most people would answer Mount Everest. They’d be wrong–Everest is the highest peak on the planet, but mountains are measured from their base to their peak, and Everest’s base sits far above sea level on the Tibetan Plateau. And when you start looking at the tallest (known) mountains in the solar system, Mount Everest, at only 2.3 to 2.9 miles tall (depending on where you decide the mountain’s base is located), doesn’t even make the list:

(1) Olympus Mons - 15.5 miles
The largest volcano on Mars is also the solar system’s tallest mountain. Measuring 374 miles in diameter, it covers about the same amount of land as the state of Arizona. Olympus Mons is located near three other volcanoes known as the Tharsis Montes. The volcanoes in this area are all 10 to 100 times bigger than Earth’s largest volcanoes. They can get this big because, unlike on Earth, there are no plate tectonics on Mars that can drag a volcano away from its hotspot–they just sit in one volcanically active place and grow bigger and bigger.

(2) Rheasilvea Mons – 13.2 miles
Rheasilvea, on the asteroid Vesta, sits at the center of a 300-mile wide crater. The asteroid is currently the subject of a close study by the spacecraft Dawn, which will continue to circle it through the first half of 2012 before moving on for a rendezvous with the asteroid Ceres in 2015. Rheasilvea Mons sometimes gets named the tallest peak in the solar system, but even with satellites and spacecraft monitoring faraway planets, moons and asteroids, measuring these things is rather difficult (which should explain why the numbers for heights given here may differ from what you’ve seen elsewhere–sources often disagree).

(3) Equatorial Ridge of Iapetus – 12.4 miles
Saturn’s moon of Iapetus has a couple of weird features. The first is a huge crater that gives the moon the appearance of the Death Star from Star Wars. The second is an equatorial ridge, with some peaks reaching over 12 miles high, that makes Iapetus look like a walnut. Scientists aren’t quite sure how the ridge formed, but they have hypothesized that it was either the remnant of the moon’s earlier oblate shape, icy material pushed up from beneath the moon’s surface or even the remainder of a collapsed ring.

(4) Ascreaus Mons – 11.3 miles
This volcano on Mars is the tallest of the three volcanoes known as the Tharsis Montes, which appear in a straight line near Olympus Mons. Ascreaus Mons has a central caldera that is 2.1 miles deep. It was first spotted by the Mariner 9 spacecraft in 1971 and then named the North Spot, as it appeared as a spot in a dust storm photographed by the spacecraft. Later images revealed it was a volcano and the spot was remaned.

(5) Boösaule Montes – 10.9 miles
Boösaule Montes is a collection of three mountains on Io, a moon of Jupiter, all connected by a raised plain. The mountain termed “South” is the tallest of the three. One side of the mountain has such a steep slope, 40 degrees, that scientists think that it was the site of a huge landslide.

(6) Arsia Mons – 9.9 miles
This is second tallest volcano from the Tharsis Montes on Mars. Based on the discovery of certain geological features on the volcano, scientists think that Arsia Mons may be home to glaciers.

(7) Pavonis Mons – 8.7 miles
Pavonis Mons is the shortest of the three volcanoes that make up the Tharsis Montes, and it has also been suggested to be home to glaciers.

(8) Elysium Mons - 7.8 miles
This Martian volcano is a big fish in a little pond, metaphorically speaking. It is the tallest volcano in the Elysium Planitia, a region in Mars’ Eastern Hemisphere that is the second largest volcanic system on the planet.

(9) Maxwell Montes - 6.8 miles
This mountain range on Venus stretches for 530 miles. Scientists aren’t sure how the mountains formed, but they think they are home to large amounts of fool’s gold (iron pyrite).

(10) Mauna Loa – 5.7 miles
Earth just squeaks into this top ten list with this active volcano on the island of Hawaii (remember, mountains are measured from their base to their peak, and Mauna Loa’s base is far beneath the ocean surface). Mauna Loa is one of many active and dormant volcanoes created by a hotspot beneath the Pacific Ocean plate. As the plate moves over the hotspot, which has been active for at least 30 million years, new islands begin to form and old ones, no longer being built up through volcanic activity, whither wither away.