Though scientists believed volcanoes on the Moon to be long dead, a recent discovery suggests they were active as recently as 800 million years ago, which is fairly recent in geological time. Even weirder, volcanoes studied on the far side of the Moon appear to have erupted with a very unusual kind of lava, made of a super-viscous liquid rock almost never seen on the satellite.

Like the Mt. Saint Helens volcano, pictured above, these recently-discovered Moon volcanoes formed giant lava domes that probably erupted in gouts of superheated gas and ash.

When you look at the Moon, you're seeing the aftermath of hundreds of volcanic eruptions. All those dark spots on the satellite's surface are deposits left from basalt rocks - mostly ejected onto the Moon's surface after meteorite hits. Until now it was believed that all volcanoes on the Moon erupted with liquid basalt, a thin, runny lava that spreads rapidly. But the shape and mineral composition of the newfound volcanoes resemble those of "dome volcanoes" on Earth. They're not predominantly basalt; instead they've erupted with rocks and minerals whose liquid form is viscous, like honey.

People who live in high latitude regions have bigger eyeballs and brains than other individuals, according to new research.

The increase in brain and eye size allows people to see better in places that receive less light than areas closer to the equator, according to the new study, published in the latest issue of the journal Royal Society Biology Letters.

The effect is most extreme at the poles.

"Someone living on the Arctic Circle would have an eyeball that is 20 percent larger than someone living on the equator," co-author Robin Dunbar told Discovery News.

"People living at high latitudes have greater visual acuity than those who live at the equator," added Dunbar, who is head of the Institute of Cognitive & Evolutionary Anthropology at the University of Oxford.

"The whole point is that they need to have better vision to compensate for the lower light levels at high latitudes, as indicated by the evidence we provide that visual acuity under ambient/natural light conditions remains constant with latitude."

The common Guiana dolphin has just divulged its sixth sense: the ability to sense electric fields. It is the first placental mammal known to pull off this trick, new research finds.

The dolphin, which bears live young like other placental mammals, most likely uses its sixth sense to find prey in the murky coastal waters it inhabits.

"Most of the animals which do this do this to find prey," said study researcher Wolf Hanke, of Rostock University in Rostock, Germany. "All of the dolphins' prey items, like crayfish, all of them generate electric fields to some degree."

The Guiana dolphin looks like the familiar bottlenose dolphin; it is only slightly smaller. It lives close to estuaries, inlets and other protected shallow waters off the north and eastern coasts of South America.

For centuries people have pondered the meaning of dreams. Early civilizations thought of dreams as a medium between our earthly world and that of the gods. In fact, the Greeks and Romans were convinced that dreams had certain prophetic powers. While there has always been a great interest in the interpretation of human dreams, it wasn't until the end of the nineteenth century that Sigmund Freud and Carl Jung put forth some of the most widely-known modern theories of dreaming. Freud's theory centred around the notion of repressed longing -- the idea that dreaming allows us to sort through unresolved, repressed wishes. Carl Jung (who studied under Freud) also believed that dreams had psychological importance, but proposed different theories about their meaning.

Since then, technological advancements have allowed for the development of other theories. One prominent neurobiological theory of dreaming is the "activation-synthesis hypothesis," which states that dreams don't actually mean anything: they are merely electrical brain impulses that pull random thoughts and imagery from our memories. Humans, the theory goes, construct dream stories after they wake up, in a natural attempt to make sense of it all. Yet, given the vast documentation of realistic aspects to human dreaming as well as indirect experimental evidence that other mammals such as cats also dream, evolutionary psychologists have theorized that dreaming really does serve a purpose. In particular, the "threat simulation theory" suggests that dreaming should be seen as an ancient biological defence mechanism that provided an evolutionary advantage because of its capacity to repeatedly simulate potential threatening events - enhancing the neuro-cognitive mechanisms required for efficient threat perception and avoidance.

So, over the years, numerous theories have been put forth in an attempt to illuminate the mystery behind human dreams, but, until recently, strong tangible evidence has remained largely elusive.

Whale-watching tourists off western Australia saw more than they expected - and perhaps more than many of them wanted - last week. As two boats of observers took in the action, a humpback whale mother desperately and vainly tried to protect a calf from four predatory orcas.

The video below, shot from a light aircraft that circled overhead as the action unfolded, isn't always easy to make out, but it shows the orcas circling as the humpback attempts to protect the calf by lifting it on to her back. (If you pause the video at about 12 seconds, you can see the whale more or less center of the screen, and the lighter-colored calf just above it.)

According to witnesses, the humpback was spotted with two calves, but the orcas swiftly came on the attack taking one. The mother only succeeded in protecting her second calf for about three-quarters of an hour before it, too, succumbed to the ambush:

"I've been diving for three years and I've never seen anything like it," said Tamar Melen, who watched the 45-minute spectacle unfold metres from the boat. Sadly, the killer whales made off with both calves. Ms Melen, 31, said they grabbed the first in seconds, but the attack on the second lasted half an hour. "It was quite impressive," Ms Melen said. "The first hit was so quick, but then they took their time with the second. It was agonising to watch the mother humpback trying to protect her calf.

A lethal bat-borne horse virus has been detected in a dog for the first time, authorities in Australia said on Tuesday, prompting fears it has jumped species.

"This is the first time outside of a laboratory that an animal other than a flying fox or a horse, or a human, has been confirmed with Hendra virus infection," Queensland state Chief Veterinary Officer Rick Symons said.

So far, 14 horses have died or been put down in Australia since June as a result of the Hendra virus, which was only discovered in 1994.

No humans have yet been infected in the current outbreak, which has affected farms in New South Wales and Queensland, but four of the seven people ever to have contracted the disease have died.

For an opinion or belief, 10 percent is critical mass. If that proportion of the population emphatically embraces an idea, then it will spread rapidly to the majority of the population, scientists have found.

"When the number of committed opinion holders is below 10 percent, there is no visible progress in the spread of ideas," said researcher Boleslaw Szymanski, director of the Social Cognitive Networks Academic Research Center at Rensselaer Polytechnic Institute. "Once that number grows above 10 percent, the idea spreads like flame."

For example, dictators who held power for decades in Tunisia and Egypt were overthrown in a matter of weeks when events pushed public opinion past the 10 percent threshold, Szymanski said.

Radioactivity and gravity may be why the strange football-shaped dwarf planet known as Haumea and its moons are unexpectedly sheathed in crystalline ice, shining in space, researchers suggest.

Haumea, named after the Hawaiian goddess of childbirth, orbits the sun beyond the path of Neptune, with two moons in orbit around it named Hi'iaka and Namaka, two of the deity's daughters.

Haumea is a bizarre dwarf planet world shaped like a cigar, or perhaps an American football, measuring about 1,200 miles (2,000 kilometers) long, and makes one full rotation in less than four hours. This is one of the fastest rotation speeds in the solar system, which gave Haumea its odd shape.

Now, surprisingly, an international research team has discovered that 75 percent of Haumea's surface is covered with crystalline water ice.

The human brain is big, and it's powerful, able to dream up innovative solutions to complex problems. Yet our brains don't age well: As we grow older, they tend to shrink and become increasingly vulnerable to cognitive dysfunctions such as memory loss and dementia. A new magnetic resonance imaging (MRI) study comparing humans and chimpanzees finds that chimp brains maintain their size as they age. Slowly losing our minds, it turns out, may be the evolutionary price we pay for having bigger brains and longer life spans.

As far as researchers can tell, humans are the only animals subject to specific brain maladies such as Alzheimer's disease, which in the United States afflicts nearly 50% of people over the age of 85. But even normal, apparently healthy human brains show the effects of aging, such as the buildup of amyloid-β plaque deposits and loss of neural connections, especially in regions linked to learning and memory. And previous studies of human brains have suggested that these brain regions, which include the frontal lobe and the hippocampus, are especially prone to shrinkage with age.

Although few similar studies of other primates have been conducted, recent research with rhesus monkeys has shown only very limited shrinkage with age. Nevertheless, the evolutionary lineages leading to humans and rhesus monkeys diverged about 30 million years ago, leaving scientists in the dark about when the human pattern of brain aging might have begun.

Scientists engaged in the search for extraterrestrial intelligence (SETI) work under the assumption that there is, in fact, intelligent life out there to be found. A new analysis may crush their optimism.

To calculate the likelihood that they'll make radio contact with extraterrestrials, SETI scientists use what's known as the Drake Equation. Formulated in the 1960s by Frank Drake of the SETI Institute in California, it approximates the number of radio-transmitting civilizations in our galaxy at any one time by multiplying a string of factors: the number of stars, the fraction that have planets, the fraction of those that are habitable, the probability of life arising on such planets, its likelihood of becoming intelligent and so on.

The values of almost all these factors are highly speculative. Nonetheless, Drake and others have plugged in their best guesses, and estimate that there are about 10,000 tech-savvy civilizations in the galaxy currently sending signals our way - a number that has led some scientists to predict that we'll detect alien signals within two decades.