For years scientists have debated the cause of the mass extinction that killed off the dinosaurs and a slew of other species on Earth 65.5 million years ago. Now, after reviewing 20 years worth of data and research, an international team of scientists concludes that it was a a huge meteorite strike that triggered the extinction.
In the late 1970s, a geophysicist discovered an impact crater in Yucatán, Mexico, and analysis showed the crater's date of origin to be the end of the Cretaceous. Geologic data indicate that the meteorite that produced the Chicxulub crater -- which lies partially buried beneath the Yucatán Peninsula -- was between 10 and 15 kilometers (6 and 10 miles) in diameter and caused an explosion on Earth that was a billion times more powerful than the Hiroshima atomic bomb.
Scientists half-jokingly call it the "ignorosphere" -- a region about 50-100 kilometers above the Earth that's too high for airplanes, but too low for satellites. "It earned its name because even though the area is valuable to researchers, there has been no easy way to get to it," said Alan Stern, planetary scientist at the Southwest Research Institute. But, Stern says, suborbital flights, like those made by Virgin Galactic's SpaceShipTwo, go right to the heart of this region, which includes the layer of the Earth's atmosphere that lies above the stratosphere and below the thermosphere.
Large amounts of methane are leaking into the atmosphere from a section of seafloor under the East Siberian Arctic Shelf, according to new study by an international research team. Methane is a greenhouse gas that lies frozen in sediments and permafrost -- frozen soil that remains below 0°C for several years -- in arctic continental shelves.
Permafrost was thought to act as a leak-proof barrier that sealed in the methane, but warming arctic temperatures are thawing the permafrost.
And the frozen methane is not only dissolving in the water -- it's escaping into the atmosphere. The researchers say that release of just a fraction of the methane stored in the shelf could trigger sudden climate warming.
Scientists estimate the number of species on Earth to be close to 10 million -- and each year, the number of known species grows. The International Institute for Species Exploration at Arizona State University and an international committee of taxonomists recently released its "Top 10" list of new species described in 2008.
Nearly four billion years ago, the Earth was pummeled by asteroids -- some as large as the state of Kansas -- during an episode known as the "Late Heavy Bombardment." Now, scientists believe that bombardment phase may have jump-started early microbial life. The results also lend support to the possibility of extreme microbial life on other planets like Mars, and perhaps even on Earth-like planets in other solar systems that may have undergone similar bombardment phases.
One look at this creature and you'll think you've stepped into a scene in Jurassic Park. But this jumbo reptile is alive and well and living in the Indonesian Islands. The Komodo dragon is the largest living lizard on Earth -- they can measure up to 10 feet long and weigh as much as 140 pounds. They also have about 60 serrated teeth and have been known to consume up to 80 percent of their body weight in a single meal. That's no garden gecko.
It's long been known that Komodo dragons pack a powerful bite, but a new study by a research team at the University of Melbourne, Australia, shows that the effectiveness of the Komodo's bite comes from a combination of venom and highly specialized serrated teeth. Using magnetic resonance imaging (MRI) techniques, the team found that the Komodo dragon has the most complex venom glands ever described for any reptile, and that its giant extinct relative Megalania (Varanus priscus) was the largest venomous animal to have ever lived.
One year ago, scientists at NASA's Jet Propulsion Laboratory, Lockheed Martin Space Systems, and the University of Arizona held their breath as the Phoenix Mars Lander hurtled toward its final descent and touchdown in the northern arctic plains of Mars. It was the first spacecraft landing on Mars without airbags since Viking 2 landed in 1976.
At 4:53:44 PM Pacific time on May 25, 2008, radio signals confirmed that Phoenix had survived its final descent and had landed safely on the Martian surface. The tricky and precise maneuvers involved with the spacecraft's entry, descent, and landing were executed in a manner described as "textbook perfect," leaving Phoenix poised almost perfectly level on the Martian surface. And the crowd at Mission Control went wild.
It's miserable enough to be under the weather in the comfort of your home, but imagine coming down with a bad cold when you're stuck inside a small crew module 200,000 miles from Earth. You're coughing on your fellow astronauts and that space food you ate half an hour ago is now floating around your zero-gravity spacecraft.
Luckily, mission control packed some antibiotics into your survival pack... but will they work in space?
The tsunami that struck Crescent City, California, on April 25, 1992, wasn't a destructive one -- the waves were relatively small, and no loss of life or significant damage resulted. But it was still an important tsunami event, in that it illustrated how quickly a wave can arrive at nearby coastal communities and how long the at-risk period can last. The tsunami occurred after a 7.1 earthquake shook the coast of Cape Mendocino on California's north coast, generating a series of tsunami waves.
The McMurdo Dry Valleys of Antarctica are one of the last places on Earth you would expect to find a new living organism. With bitter cold temperatures and only about four inches of annual snowfall, scientists consider these valleys to be one of Earth's most extreme and harsh environments.
The region was believed to be devoid of complex animal and plant life, but a new study has revealed that an unusual microbial life form lives under the Taylor Glacier -- an outlet glacier that drains part of the East Antarctic Ice Sheet and terminates in the Dry Valleys.