Darwin first saw the H.M.S. Beagle 183 years ago today

September 11, 2014 Leave a comment

Charles Darwin gained his fame as the man who, along with Alfred Russel Wallace, hypothesized that Earth’s biodiversity is the result of evolution by natural selection. In the century and a half since Darwin’s pioneering publication of “The Origin of Species,” scientists have found that his ideas about how and why species change were essentially correct. Evolution by natural selection is as much a part of the fabric of science and just as important an explanation of how nature works as Copernicus’ contribution that Earth revolves around the sun and Newton’s insights on gravity.

Today is the 183rd anniversary of the date on which Darwin first saw the H.M.S. Beagle, the ship that took him on the journey that changed biology.

This drawing is a reproduction of R. T. Pritchett's frontispiece from the 1890 illustrated edition of The Voyage of the Beagle. Courtesy Wikimedia.

This drawing is a reproduction of R. T. Pritchett’s frontispiece from the 1890 illustrated edition of The Voyage of the Beagle. Courtesy Wikimedia.

You can watch a wonderful short film about Darwin’s life and work here.

Scientists discover first known aquatic dinosaur in Morocco

September 11, 2014 Leave a comment

Paleontologists have discovered the first dinosaur known to have lived much of its life in the water.

The find of a variety of bones from an animal called Spinosaurus aegyptiacus vastly improves scientists’ understanding of the role played by the huge predatory dinosaur in the Cretaceous period ecosystem of modern-day North Africa.

“Today we are resurrecting a giant from deep time,” Dr. Nizar Ibrahim, a paleontologist at the University of Chicago and the lead author of a paper published in the Sept. 11, 2014 edition of Science Express, said. “The animal we are resurrecting is so bizarre, it is going to force dinosaur experts to re-think many things they thought they knew about dinosaurs.”

Spinosaurus aegyptiacus was first identified in 1915 by the German anatomist, geologist, and paleontologist Ernst Stromer von Reichenbach. He identified an animal unlike any other theropod dinosaur then known.

Spinosaur fossils mounted on the wall of a German museum before a Royal Air Force bombing in 1944. Courtesy Washington University.

Spinosaur fossils mounted on the wall of a German museum before a Royal Air Force bombing in 1944. Courtesy Washington University.

“The size of the bones suggested to Stromer that the animal rivaled Tyrannosaurus rex in size, but it clearly differed from the North American predator in many ways,” Ibrahim said. “The skull was more elongate and the tall spines formed a large sail on the back of Spinosaurus.”

Stromer stored the holotype in the Paläontologische Staassammlung in Munich, Germany. Unfortunately, an April 1944 bombing raid by Britain’s Royal Air Force destroyed Stromer’s fossils.

The German scientist’s drawings survived.

Stromer's drawings of Spinosaurus aegyptiacus were detailed and survived the World War Ii bombing. Courtesy Wikimedia.

Stromer’s drawings of Spinosaurus aegyptiacus were detailed and survived the World War Ii bombing. Courtesy Wikimedia.

During the ensuing decades paleontologists used those drawings, along with a few fragmentary finds of additional Spinosaurus remains, to develop a rudimentary idea of the animal’s appearance. They conceived Spinosaurus as a land animal, the largest predatory dinosaur known.

The findings published Thursday cast no doubt on Spinosaurus’ size, but revealed a number of body features that are unique among dinosaurs and that indicate the animal likely searched for food in the rivers that were ubiquitous in the region now known as North Africa during the Mesozoic era. Those features include a nasal opening high on the skull, long teeth shaped like cones, and wide and flat feet that may have been webbed.

“Other more subtle, but equally startling, finds were made,” Dr. Paul C. Sereno, a vertebrate paleontologist at the University of Chicago and a principal author of the paper published online in Science Express, said. “The thigh bone was robust and shorter than the shin bone, a very unusual proportion for a large dinosaur. And all of the long bones were solid without a marrow cavity, something never before observed in a predatory dinosaur.”

The highly dense bones are similar to those found in modern-day penguins.

“This adaptation is useful to facilitate buoyancy control,” Dr. Simone Maganuco, a vertebrate paleontologist at Italy’s Museo di Storia Naturale di Milano and another co-author on the paper, said.

Spinosaurus’ skull also exhibited small pits at the end of its snout called foramina. The authors of the study used computer tomography to examine them and found that they served to regulate pressure.

The foramina closely resemble those found in modern-day crocodiles and that have been confirmed in at least one species of extinct marine reptile.

“The pressure receptors of crocs play a key role in capturing prey based on water movements, and permit to hunt even in darkness or in muddy water, without relying on sight,” Dr. Cristiano Dal Sasso, curator of vertebrate paleontology at the Museo di Storia Naturale di Milano and a co-author of the paper, said.

She explained that their presence in Spinosaurus’ skull is an indication that the dinosaur may have used its long snout to find prey, with no need to see it.

Sereno noted that the new Spinosaurus specimen also exhibited a tail with characteristics similar to those found in some modern fish.

“These facts strongly supported a semi-aquatic existence for Spinosaurus, the first water-adapted non-avian dinosaur on record,” Sereno said.

The spines on the animal’s back and the sail-like structure they formed were a means of communication.

“Even the big sail on the back of Spinosaurus may, in part, be an adaptation to a life often spent in water,” Ibrahim said. “It would have been a great display structure, and would remain visible even when the animal is partially submerged.”

Spinosaurus would not have been an agile creature, at least on land, and would have had most of its weight at its front.

“How it walked on land and swam are of much interest, its center of gravity far forward compared to other land-based predators,” Sereno said. “Foot-propelled paddling with webbed feet seems likely, to explain the anatomical findings at the rear of the beast. At the other end, its neck and trunk are particularly long, which give the skeletal model and mount its record-shattering 50-foot length. The bones at the base of the neck are also adapted for bending downward, perhaps for fishing while swimming.”

Nevertheless, Sereno explained, the animal would have been a formidable opponent of any land predator of its time, including the nearly T-rex-sized Carcharodontasaurus.

“Spinosaurus had a large head,” Sereno said. “It was nothing to sneer at. You would not want to encounter this animal.”

The fossils that serve as the basis for the new paper are of one individual, which also help scientists to understand the proportions of Spinosaurus aegyptiacus.

The new Spinosaurus remains were found in the Kem-Kem fossil beds of southeastern Morocco.

On Friday the National Geographic Society will premiere an exhibition in Washington, D.C. focused on Spinosaurus aegyptiacus.

NASA probe detects class X solar flare

September 11, 2014 Leave a comment

The sun emitted a class X1.6 solar flare Wednesday.

The Solar Dynamics Observatory photographed the event at 11:48 am MDT.

Today's solar flare is visible in the center of the sun. The Solar Dynamics Observatory captured the image in the 131 angstrom range. Courtesy NASA/SDO.

Today’s solar flare is visible in the center of the sun. The Solar Dynamics Observatory captured the image in the 131 angstrom range. Courtesy NASA/SDO.

 

SDO films solar flare

The Solar Dynamics Observatory captured an array of images of a solar flare on Aug. 24. This one spectacularly shows the locus of the flare, on the left side of the sun.

This image of the  Aug. 24, 2014 solar flare was captured by the Solar Dynamics Observatory at 5:16 am MDT. Image courtesy NASA, SDO.

This image of the Aug. 24, 2014 solar flare was captured by the Solar Dynamics Observatory at 5:16 am MDT. Image courtesy NASA, SDO.

You can see more images of this week’s flare at SDO’s Facebook page or on the mission website.

Solar flares are energy releases. They happen when electrons, which carry a negative electrical charge, encounter the sun’s plasma. When that occurs, an explosion occurs and the particles are rapidly heated. Accelerated to very high velocities, they then move through the sun’s atmospheric layers and disperse into the solar system. When they reach the vicinity of Earth, they can pose a radiation hahttps://wordpress.com/post/zard to spacecraft and the astronauts inside them.

Solar flares are sometimes accompanied by an independent phenomenon known as a coronal mass ejection, in which atoms and ions are expelled from the star and sent on a high-speed journey through space. Coronal mass ejections can damage satellites, including those that transmit worldwide communications and provide geographic positioning system information, and disrupt the transmission of electricity on the planet. They can also impair the functioning of electronic devices on board high-altitude aircraft.

This week’s solar flare was not among the most powerful known to occur on the sun. Scientists measure the intensity of a flare according the amount of flux they produce in x-rays near Earth. There are five classes, ranked from weakest to most powerful: A,B, C, M, and X. Each of the classes involve flares that are about ten times more powerful than the next-lower class on the scale.

Within each class of solar flare there are numbered divisions that allow a more precise distinction between solar flares to be drawn. 

Sunday’s event was an M5 flare, which means that it was not as powerful as the X5.4-class flare that occurred on March 6, 2012, the X5-class “Bastille Day Storm” on July 14, 2000, or the X17-class (or maybe even an X28-class) event that wowed scientists in October 2003.

The October 28, 2003 flare was powerful enough to induce the European Space Agency to put its Solar and Heliospheric Observatory in a “safe mode,” so that sensitive instruments on board would not be damaged. The event caused numerous aircraft flight delays and forced astronauts aboard the International Space Station to take cover in an area shielded from the solar radiation. The operation of several satellites in Earth’s orbit was disrupted and even space probes as far away as Mars and Saturn were affected.

This image of the Oct. 28, 2003 solar flare was captured by ESA's Solar and Heliospheric Observatory. Image courtesy ESA.

This image of the Oct. 28, 2003 solar flare was captured by ESA’s Solar and Heliospheric Observatory. Image courtesy ESA.

The Bastille Day storm caused some radio broadcast disruptions and some damage to satellites.

You can learn more about well-known solar flare incidents here.

Bastille Day flare as seen by SOHO

This image of the July 14, 2000 Bastille Day storm was captured by the European Space Agency’s Solar and Heliospheric Observatory. SOHO used its Extreme Ultraviolet Imaging Telescope to capture it. Image courtesy ESA.

NYT: Draft UN report warns that GHG emissions are rising too fast to be contained

A draft United Nations report has bad news on climate: greenhouse gas emissions are rising faster than the efforts to contain and reduce them are succeeding in lowering them.

Today’s New York Times article said that the draft report concludes that “severe, pervasive, and irreversible impacts” are unavoidable unless the trend is reversed within a decade or two at most.

Among those impacts that are already occurring are increases in sea levels, extreme weather phenomena including heat waves and heavy rains, lowered grain production, and losses of polar ice.

According to a Nov. 2013 report by the World Meteorological Association, worldwide GHG emissions hit a record in 2012, with 35.6 metric tons discharged. In fact, the decade 2000-2010 was the warmest in the historical record. Climate data has been obtained and archived around the world since about 1850.

During 1970-2000, GHG pollution rose by only about 1.2 percent per year.

The IPCC report was released to governments around the world earlier this month for comment. It is due to be released to the general public on Nov. 2 in Copenhagen, Denmark.

Possible sites for Philae landing on comet announced

This annotated image shows four of the five possible landing sites on comet 67P/Churyumov-Gerasimenko for the Philae lander. Image courtesy European Space Agency.

This annotated image shows four of the five possible landing sites on comet 67P/Churyumov-Gerasimenko for the Philae lander. Image courtesy European Space Agency.

Researchers have chosen five possible landing sites for a spacecraft that will attempt in November to become the first ever to land on a comet.

The European Space Agency will consider several factors in making the final choice of a landing site on comet 67P/Churyumov-Gerasimenko for the Philae lander, including whether it has obstacles to landing and whether the amount of solar energy appropriate for the lander’s power array is available.

“The candidate sites that we want to follow up for further analysis are thought to be technically feasible on the basis of a preliminary analysis of flight dynamics and other key issues – for example they all provide at least six hours of daylight per comet rotation and offer some flat terrain,” Steven Ulamec, the lander manager at the German Aerospace Center in Cologne, Germany,, said. “Of course, every site has the potential for unique scientific discoveries.”

One of the most basic factors that will influence the choice of a landing site is whether it is one to which the lander can be accurately guided. That challenge is magnified somewhat by the unusual shape of comet C-G, which has been likened to a rubber duck.

“Depending on where you try to make the lander land, the errors associated with everything can actually vary,” Dr. Daniel Scheeres, a professor of aeronautical engineering at the University of Colorado at Boulder and an expert in the navigation of space vehicles, said. “There will be regions on the surface where they can be more accurate than others.”

Another problem for mission planners is whether a potential site impedes Philae’s ability to anchor itself to the surface and remain upright. Rocky sites pose hazards to the spacecraft, but there’s no guarantee that a smooth site would be one to which the lander could be easily guided.

“There’s no reason why the easiest spot is also going to be the smoothest spot,” Scheeres said. “That’s where the challenge is going to be. They’ll have to make some sort of compromise.”

Yet another consideration will be the degree of solar illumination that predictably hits the landing site. Philae depends on batteries rechargeable by sunlight for its power.

“The real issue is what happens if the sun is blocked,” Scheeres explained. “Then you lose the power. And the comet is rotating. Even if you put it in the right spot, in a half a day it’s going to be in the dark.”

Because the movement of the comet will prevent Philae’s batteries from being constantly re-charged, it will be important for the landing site to be fully illuminated when that area of the comet faces the sun.

“If it lands somewhere where it’s shadowed, once the batteries are dead it won’t get any more power,” Scheeres said.

ESA faces a mid-September deadline to choose Philae’s destination on the comet. It will continue to gather information about the five potential landing sites for several more weeks.

“The process of selecting a landing site is extremely complex and dynamic; as we get closer to the comet, we will see more and more details, which will influence the final decision on where and when we can land,” Fred Jansen, the Noordwijk, The Netherlands-based Rosetta mission manager, said.

Three of the possibilities are located on the comet’s smaller lobe, while two are on the larger lobe.

Each of the sites must accommodate the one square meter-sized Philae lander, which will examine the chemical and physical structure of the comet and obtain close-up images of the comet’s nucleus.

Actual landing of Philae will occur when Rosetta and comet C-G are about 450 million kilometers from the sun.

Researchers want to make the attempt before the comet gets too close to the sun. Too much solar energy would make landing, and operation of the lander once on the surface of the comet, more difficult.

Rosetta is currently in orbit around the comet. It will continue efforts to study the comet through 2015, following it through an orbit around the sun.

This frame from the film "Chasing a Comet - The Rosetta Mission" shows an artist's conception of the Philae lander approaching comet 67P/Churyumov-Gerasimenko.

This frame from the film “Chasing a Comet – The Rosetta Mission” shows an artist’s conception of the Philae lander approaching comet 67P/Churyumov-Gerasimenko.

Categories: space exploration Tags: ,

NASA Image of the Day, Aug. 25, 2014

Neptune, as seen by Voyager 2 on Aug. 20, 1989

Neptune, as seen by Voyager 2 on Aug. 20, 1989. The photo was obtained after the probe’s on-board camera took multiple images while traveling about 4.4 million miles from the planet. The Great Dark Spot is visible near the center of the image. Photo courtesy NASA.

Categories: NASA Image of the Day
Follow

Get every new post delivered to your Inbox.

Join 108 other followers