Some say that ancient Maya calendars end on December 21, 2012, predicting the end of the world as we know it. Scientists have refuted this notion for years, but some refuse to listen.

A new, surprising Maya ruins finding, published last week in Science, again confirms that the end of the world is not nigh.

The authors of the paper say that despite popular belief, the Maya calendar does not end in the year 2012 but simply starts another of its calendar cycles. “It’s like the odometer of a car, with the Maya calendar rolling over from the 120,000s to 130,000,” says Anthony Aveni, professor of astronomy and anthropology at Colgate University, and a co-author of the new paper. “The Maya just start over.”

“The ancient Maya predicted the world would continue, that 7,000 years from now, things would be exactly like this,” lead author William Saturno confirms. “We keep looking for endings. The Maya were looking for a guarantee that nothing would change. It’s an entirely different mindset.”

The ruins in the new paper were discovered in Xultún in Guatemala’s rainforest-covered Petén region. Researchers uncovered a structure that contains what appears to be a work space for the town’s scribe, its walls adorned with unique paintings—one depicting a lineup of men in black uniforms—and hundreds of scrawled numbers. Many numbers involve calculations related to the Maya calendar.

The amazing thing is that this structure is from the 9th Century, making it hundreds of years older than previously discovered (but similarly non-apocalypse predicting) Maya calendars.

Even the structure’s discovery is remarkable—looters have ravaged the surrounding region, and by all accounts, the paintings shouldn’t have lasted these 1,200 years. “It’s weird that the Xultún finds exist at all,” Saturno says. “Such writings and artwork on walls don’t preserve well in the Maya lowlands, especially in a house buried only a meter below the surface.”

(Discover’s 80beats blog has a great illustration of the house-like structure.)

The mural also represents the first Maya art found on the walls of a house. “There are tiny glyphs all over the wall, bars and dots representing columns of numbers. It’s the kind of thing that only appears in one place—the Dresden Codex—which the Maya wrote many centuries later. We’ve never seen anything like it,” says David Stuart, of the University of Texas, who deciphered the glyphs.

The glyphs appear to represent the various calendrical cycles charted by the Maya—the 260-day ceremonial calendar, the 365-day solar calendar, the 584-day cycle of the planet Venus and the 780-day cycle of Mars, as well as lunar semesters lasting 177 and 178 days. It seems that the Maya, too, had a way to deal with the extra day (think Leap Year).

This structure discovered by Saturno’s team was numbered 54 out of 56 total counted and mapped by a Harvard team in the 1970s. Thousands more at Xultún remain uncounted. And Nature News reports that:

The researchers identified 12 other etched or painted inscriptions in addition to those described in the Science paper, and analysis and excavation at Xultún continues. “We have 99.9% left to explore,” said Saturno. “We’re going to be working on it for many decades to come.”

Want more information? The work is funded by the National Geographic Society and is featured in the June issue of National Geographic magazine with a video on the project available here. The wall mural was photographed as a high-resolution panoramic gigapan, creating a zoomable view for users to explore the painting in detail. Enjoy! (You’ve got plenty of time, since the world isn’t ending any time soon…)

What can a good-sized asteroid (330 miles across) tell us about the formation of our solar system and planet? A lot, if that asteroid is Vesta.

Launched in September 2007, the Dawn spacecraft mission marked the first prolonged visit to the main asteroid belt, entering Vesta’s orbit last July. The second largest and brightest asteroid in the asteroid belt, Vesta has a surface marked by basaltic flows, which have long sparked astronomers’ interest. Dawn’s discoveries have confirmed scientists’ suspicions that Vesta is an intriguing place…

Dawn’s mission includes collecting data from both high- and low-altitude orbits around Vesta—a recent NASA video shows simulated flights around the asteroid based on current imagery. With a press conference and series of papers in the journal Science last week, NASA marked the end of Dawn’s low-altitude orbit. The spacecraft will move to a high-altitude orbit of the northern hemisphere this summer when the area is more lit by sunlight, likely resulting in many more findings. Dawn will leave Vesta on August 26th and head to the neighboring dwarf planet, Ceres.

The new studies reveal that, for an asteroid, Vesta is very planet-like, possessing an Earth-like internal structure. Dawn is equipped to measure slight changes in the gravitational pull on the spacecraft, which allows astronomers to explore the internal structure of Vesta—it seems to have an iron core underneath its mantle and crust, similar to Earth. Together with information about surface temperatures and composition, these findings suggest that Vesta is a protoplanet—a planet whose full development failed due to a small mass.

For Vesta to have developed its iron core, it must have been extremely hot during the early history of the Solar System, some 4.56 billion years ago. To explore this hypothesis, astronomers used data from the Framing Camera and the Visible and Infrared Mapping Spectrometer. The Framing Camera found evidence that Vesta once possessed a subsurface magma ocean, which could have existed only if the asteroid was extremely hot. The asteroid has chilled off quite a bit since then—now Vesta has temperatures between –10° and –150° Fahrenheit, depending on the amount of sunshine.

The Dawn mission has also explored the ages of two large impacts on the southern hemisphere: the newest crater on the southern hemisphere of Vesta dates to a mere one million years ago, and the older of the two is about twice as old. The freshness and brightness of these recently-produced craters allow astronomers to extrapolate more about the Solar System’s history.

“The large impact basins on the Moon are all quite old,” says David O’Brien, a Dawn participating scientist from the Planetary Science Institute. “The fact that the largest impact on Vesta is so young was surprising.”

Some of the meteorites found on Earth contain traces of pyroxene, a material rich in iron and magnesium. This resembles the material on Vesta, confirming earlier theories that many Earth-bound meteorites originated from Vesta. The Dawn mission confirms that 6% of Earth’s meteorites came from Vesta, which puts Vesta at the top of the list for the largest contributor to Earth’s meteorite impacts.

An infographic of Dawn’s mission can be found at Space.com.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and volunteers for the Morrison Planetarium.

Groupers are a family of fishes often found in coral reefs and prized for their quality of flesh. But they’re facing critical threats to their survival. As part of the International Union for Conservation of Nature (IUCN) Species Survival Commission, researchers have spent the past ten years assessing the status of 163 grouper species worldwide.

Publishing in the journal Fish and Fisheries, the team reports that 20 species are at risk of extinction if current overfishing trends continue, and an additional 22 species are categorized as Near Threatened.

“Fish are one of the last animal resources commercially harvested from the wild by humans, and groupers are among the most desirable fishes,” says Rocha. “Unfortunately, the false perception that marine resources are infinite is still common in our society, and in order to preserve groupers and other marine resources we need to reverse this old mentality.”

The team estimates that at least 90,000,000 groupers were captured in 2009. This represents more than 275,000 metric tons of fish, an increase of 25% from 1999, and 1600% greater than 1950 figures.

Because groupers fetch a high price in the fish market (estimated to be a multi-billion dollar per year industry), they are often among the first reef fishes to be overexploited. Their disappearance from coral reefs could upset the ecological balance of these threatened ecosystems, since they are ubiquitous predators and may play a large role in controlling the abundance of animals farther down the food chain.

Unfortunately, groupers take many years (typically 5-10) to become sexually mature, making them vulnerable for a relatively long time before they can reproduce and replenish their populations. In addition, fisheries have exploited their natural behavior of gathering in great numbers during the breeding season. The scientists also conclude that grouper mariculture has not mitigated overfishing in the wild.

Although the prognosis is poor for the restoration and successful conservation of Threatened grouper species, the authors do recommend some courses of action, including optimizing the size and location of Marine Protected Areas, minimum size limits for individual fish, quotas on the amount of catch, limits on the number of fishers, and seasonal protection during the breeding season. However, the scientists stress that “community awareness and acceptance, and effective enforcement are paramount” for successful implementation, as well as “action at the consumer end of the supply chain by empowering customers to make better seafood choices.”

Image: Greg Grimes/Wikipedia