Courtesy Mike Hartmann via PLoS OneSince the 1940s the "walking rocks" of Death Valley's Racetrack Playa have mystified visitors and scientists alike. Rocks of various size (up to 700 lbs!) somehow move across the dry lakebed. Nobody ever seemed to witness their actual movement, but the rocks definitely did move, leaving long telltale tracks behind. What was the cause? High winds? Slippery slopes of algae? Aliens? No one could say for certain.
Now, a research team from Scripps Institution of Oceanography at the University of California-San Diego has tackled the problem and seems to have solved the mystery.
The unusual phenomenon, it turns out, requires a special sequence of events that the environment at Racetrack Playa evidently provides.
The first step requires the playa's basin to fill with just enough water to surround the rocks but not too deep to cover them. Next, as nighttime temperatures fall, the water freezes into a quarter-inch thick sheet of ice. In the morning, as the rising sun begins to melt the ice sheet, it causes it to break into smaller floating panels. Finally, light winds - as light as 10mph in strength - gently blow these panels into the rocks and push them across the playa at a speed of only a few inches per second. Since the movement of the rocks is synchronized, even if someone was observing the phenomenon directly, they may not notice the rocks are moving.
In 2011, the research team, led by co-authors Jim Norris and Richard Norris, positioned their own sample blocks of limestone on the dry lakebed each fitted with a GPS unit to record movement (park authories wouldn't allow them use any native rocks). A high-resolution weather station was also set up to measure wind velocity. A magnet positioned beneath each sample rock triggered the GPS devices once the rocks began to move. Since all the special conditions had to be met in order for the rocks to move, the researchers were somewhat suprised when they returned two years later to see a pond of three inches of water covering the playa. It was a perfect set-up to study their hypothesis. Eventually ice formed on the pond's surface, and at the very end of 2013 it began to break up and move the rocks in the process. A camera recorded timelapse of each event.
"We documented five movement events in the two and a half months the pond existed and some involved hundreds of rocks," said Richard Norris, "So we have seen that even in Death Valley, famous for its heat, floating ice is a powerful force in rock motion."
Read the entire study online in the journal PLoS One.
This is so cool. Cameras attached to the space shuttle's solid rocket boosters (SRB) give an out-of-this-world view (literally!) of a launch from the Kennedy Space Center at Cape Canaveral. The video is compiled from a couple different missions flown during the shuttle program's hey-day. All the audio comes from microphones mounted on the shuttle and was mixed and enhanced by the guys over at Skywalker Sound. If you want more, you can watch video of the SRBs' recovery at sea or enjoy various camera angles of several shuttle launches. What a tremendous ride!
Courtesy Public domain via WikipediaToday is the 245th anniversary of the birth of naturalist Jean Léopold Nicolas Frédéric Cuvier born in 1769 in Montbéliard, a French-speaking (but not French ruled) region in the Jura Mountains. In 1795, Georges Cuvier (as he was known) went to Paris where, eventually he was appointed a professor of animal anatomy at the Musée National d'Histoire Naturelle. Cuvier is considered one of the founders of comparative anatomy and vertebrate paleontology, and helped establish the idea of extinction as a scientific fact.
Courtesy Minnesota Department of HealthThink you can get away from Science Buzz by going to the Minnesota State Fair? Think again. You'll have three different opportunities to see Science Buzz exhibits if you visit the Fair through Labor Day.
At the Education Building, the Minnesota Department of Health will be presenting hands-on and digital activities about the importance of vaccinations. Those activities are available daily from 9 a.m. to 9 p.m.
Visitors to the Eco Experience building can learn about new data and trends on climate change at a computer kiosk being presented by the Minnesota Pollution Control Agency and Science Buzz. It is also open 9 a.m. to 9 p.m. daily. Here's a link to those pages if you can't make it to the Fair.
Also, on Friday, Aug. 29, faculty from the University of Minnesota's Institute for Math and its Applications will be showing a number of hands-on math activities at the university's exhibit building, including the popular Traveling Salesman Problem game board. They will also be presenting from 9 a.m. to 9 p.m. that day. Here's a link to the Buzz's online content on the Traveling Salesman Problem.
This video is both fascinating and unsettling. I feel sorry for the poor little avian dinosaur.
Courtesy Craig Dietrich - FlickrA huge solar energy farm in the Mojave Desert seems to be having one serious side effect: passing birds in flight are bursting into flames.
What's going on is that 300,000 mirrors on the ground are directing sunlight to huge towers that convert that energy into electricity. Bugs are attracted to the bright light from the mirrors drawing hungry birds to get into the path of the reflected light. And that concentrated light energy is causing the birds to catch fire, sometimes at a rate of one every two minutes. The flaming birds have been noticed since the plant powered up in February and its estimated that the total bird kill this year could top out at 28,000. Researchers estimated that one bird they found dead had been roasted by light beams that were nearly 1,000 degrees F.
Plans for building a second plant are on hold while investigators study the situation at the current site. What do you think? Is the potential of killing many birds a worthwhile cost for increased clean, "green" electricity?
Courtesy M. R. Smith / Smithsonian InstituteOne of the strangest and more mysterious critters that scurried across the Middle Cambrian seafloor has baffled paleontologist since it was first identified in the 1970s. Was it a worm? Which side was up? Did it have legs or spikes or both? Was its head actually its tail? Did it have any extant descendents or was it an evolutionary dead-end? The worm-like creature was so baffling and so bizarre, it was given the very apropos name of Hallucigenia.
The tubular, spiked-worm possessed seven or eight pairs of legs and ranged in length from 2/5th of an inch to one and 1/4 inches and looks like something out of a bad dream. Early interpretations of their fossils were all over the map. The stiff spikes on it back were first thought to be its legs, and its legs misidentified as tentacles. What was thought to be its tail ended up being its head.
Using modern imaging technology, researchers from the University of Cambridge have been closely studying fossils from the famous Burgess Shale quarry located high in the Canadian Rockies, and are uncovering Hallucigenia's secrets. By studying the claws at the end of its legs they have been able to link it to modern velvet worms (onychophorans). Scientists have long suspected the two were somehow related but until now have failed to find anything significant to prove it. By studying Hallucigenia's claws they've determined that they're constructed of nested cuticle layers, very similar to how the jaws of velvet worms are organized. The similarity is no surprise since jaws are known to have evolved from a modified set of front legs.
But besides giving Hallucigenia a place in the lineage of life on Earth, the Cambridge team during the course of their study also discovered something else: that arthropods - which include crustaceans, spiders, insects and trilobites - aren't in fact as closely related to velvet worms as previously thought.
“Most gene-based studies suggest that arthropods and velvet worms are closely related to each other," said co-author Dr Javier Ortega-Hernandez. "However, our results indicate that arthropods are actually closer to water bears, or tardigrades, a group of hardy microscopic animals best known for being able to survive the vacuum of space and sub-zero temperatures – leaving velvet worms as distant cousins.”
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This is an excellent TED presentation about how astronomers gather lots of information about the far reaches our universe just by studying light.
This video, alleged by some viewers to show a humanoid figure and its shadow on the surface of the Moon, has gone viral (over 3 million views!). If it is a man or alien being, he's a very, very big boy. It's also been pointed out that his shadow is going the wrong way when compared to shadows made by nearby moonscape features. Fanciful fun, but that's about it.
Here are the co-ordinates (27°34'26.35"N 19°36'4.75"W) if you want to find the exact location yourself on Google Moon, which is accessed under the Saturn-shaped menu in the toolbar of the latest version of Google Earth.