Stories tagged Earth and Space Science

Oct
30
2011

Thailand Flooding from Space
Thailand Flooding from SpaceCourtesy NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
From the NASA Image of the Day on October 28:

Since July 2011, heavy monsoon rains in southeast Asia have resulted in catastrophic flooding. In Thailand, about one third of all provinces are affected. On Oct. 23, 2011, when this image from ASTER, the Advanced Spaceborne Thermal Emission and Reflection Radiometer instrument on NASA's Terra spacecraft was acquired, flood waters were approaching the capital city of Bangkok as the Ayutthaya River overflowed its banks. In this image, vegetation is displayed in red, and flooded areas are black and dark blue. Brighter blue shows sediment-laden water, and gray areas are houses, buildings and roads. The image covers an area of 35.2 by 66.3 miles (56.7 by 106.9 kilometers) and is located at 14.5 degrees north latitude, 100.5 degrees east longitude.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change.

Oct
26
2011

Trajectory of comet Elenin
Trajectory of comet EleninCourtesy NASA/JPL-Caltech
Below is a news release from NASA/JPL about a comet that is going through some difficult times. NASA is sort of harsh in this release, imho, and really does not take the comet's feelings into account. Take a gander to see what I mean. Even the title is a little severe.

NASA Says Comet Elenin Gone and Should Be Forgotten

Comet Elenin is no more.

Latest indications are this relatively small comet has broken into even smaller, even less significant, chunks of dust and ice. This trail of piffling particles will remain on the same path as the original comet, completing its unexceptional swing through the inner solar system this fall.

"Elenin did as new comets passing close by the sun do about two percent of the time: It broke apart," said Don Yeomans of NASA's Near-Earth Object Program Office in Pasadena, Calif. "Elenin's remnants will also act as other broken-up comets act. They will trail along in a debris cloud that will follow a well-understood path out of the inner solar system. After that, we won't see the scraps of comet Elenin around these parts for almost 12 millennia."

Twelve millennia may be a long time to Earthlings, but for those frozen inhabitants of the outer solar system who make this commute, a dozen millennia give or take is a walk in the celestial park. Comet Elenin came as close as 45 million miles (72 million kilometers) to the sun, but it arrived from the outer solar system's Oort Cloud, which is so far away its outer edge is about a third of the way to the nearest star other than our sun.

For those broken up over the breakup of what was formerly about 1.2 miles (two kilometers) of uninspiring dust and ice, remember what Yeomans said about comets coming close to the sun – they fall apart about two percent of the time.

"Comets are made up of ice, rock, dust and organic compounds and can be several miles in diameter, but they are fragile and loosely held together like dust balls," said Yeomans. "So it doesn't take much to get a comet to disintegrate, and with comets, once they break up, there is no hope of reconciliation."

Comet Elenin first came to light last December, when sunlight reflecting off the small comet was detected by Russian astronomer Leonid Elenin of Lyubertsy, Russia. Also known by its astronomical name, C/2010 X1, Elenin somehow quickly became something of a "cause célèbre" for a few Internet bloggers, who proclaimed this minor comet could/would/should be responsible for causing any number of disasters to befall our planet.

Internet posts began appearing, many with nebulous, hearsay observations and speculations about earthquakes and other disasters being due to Elenin’s gravitational effects upon Earth. NASA’s response to such wild speculations was then in turn speculated to be an attempt to hide the truth.

"I cannot begin to guess why this little comet became such a big Internet sensation," said Yeomans. "The scientific reality is this modest-sized icy dirtball's influence upon our planet is so incredibly miniscule that my subcompact automobile exerts a greater gravitational influence on Earth than the comet ever would. That includes the date it came closest to Earth (Oct. 16), when the comet’s remnants got no closer than about 22 million miles (35.4 million kilometers)."

Yeomans knows that while Elenin may be gone, there will always be Internet rumors that will attempt to conjure up some form of interplanetary bogeyman out of Elenin, or some equally obscure and scientifically uninteresting near-Earth object. Thinking of ways to make himself any more clear about the insignificance of this matter is somewhat challenging for a scientist who has dedicated his life to observing asteroids and comets and discovering their true nature and effects on our solar system.

"Perhaps a little homage to a classic Monty Python dead parrot sketch is in order," said Yeomans. "Comet Elenin has rung down the curtain and joined the choir invisible. This is an ex-comet."
NASA detects, tracks and characterizes asteroids and comets passing relatively close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes the physical nature of a subset of them, and predicts their paths to determine if any could be potentially hazardous to our planet. There are no known credible threats to date.

Its like the person writing this had a personal vendetta against this poor comet. Though the Monty Python reference at the end helps lighten the mood, the overall dismissive tone of this news release is a bit sad.

Poor Elenin and its remaining "piffling particles".

Oct
21
2011

Soyuz VS01 at Launch Pad in French Guiana
Soyuz VS01 at Launch Pad in French GuianaCourtesy ESA

This morning (October 21, 2011), at 10:30 Greenwich Mean Time (5:30am Central Daylight Time), a Soyuz rocket lifted off from a brand new launch pad in the South American jungle with two European navigation satellites, making history on its first mission from Guiana Space Center. Russia and Europe opened the new Soyuz launch site to allow the Russian rocket to better compete for commercial and European space missions. By launching close to the equator in French Guiana, the Soyuz rocket gets a boost in performance.

In 1998, the European Space Agency (ESA) first began studying the possibility of Soyuz launches from the Guiana Space Center. ESA officially started this program in 2004, with construction work in French Guiana beginning in 2005 and the first Russian components arriving three years later, in 2008.

This launch, designated VS01 in Arianespace’s launcher family numbering scheme, will deploy two Galileo satellites. Galileo is Europe’s program for a global navigation satellite system to provide highly accurate, global positioning services, and will be interoperable with the U.S. Global Positioning System and Russia’s Glonass network.

The newspaper El Mundo has an informative animation on the launch vehicle and Galileo satellite (in Spanish).

See video

Oct
15
2011

Giant bison skull: its horns spanned 6 feet 4 inches. Behind stands Dr. Steve Holen, curator of archaeology at the Denver Museum of Nature & Science
Giant bison skull: its horns spanned 6 feet 4 inches. Behind stands Dr. Steve Holen, curator of archaeology at the Denver Museum of Nature & ScienceCourtesy Photo by Heather Rousseau ©Denver Museum of Nature and Science
The last talk I attended at the Geological Society of America (GSA) convention this past week was one of my favorites. It was an update of the Snowmastodon Project given by Kirk Johnson, chief curator at the Denver Museum of Nature and Science (DMNS). Just one year ago, a construction worker bulldozing for a dam-building project at the Zeigler Reservoir near Snowmass Village in Colorado unearthed a mammoth tusk. Paleontologists and archaeologists from the Denver museum were called in, and excavation of a small portion of the drained reservoir bottom soon got underway. The museum crew worked for just one month, until November 14, 2010, when snowfall halted the project. Then last spring scientists returned to the site and were allowed just 51 days to excavate the fossil deposits before the Snowmass Water and Sanitation District resumed their expansion work on the reservoir.

This time more research experts from the US, Canada, and England joined the dig along with a slew of interns and volunteers, totaling some 233 people working on the project. Over the next seven weeks excavation at the Zeigler Reservoir site progressed at a frantic pace. According to Johnson, anywhere from 15 to 90 diggers were on site each day digging out fossils from the ancient peat and mud deposits, from what once were the shores of a small glacial lake. Despite the short window of opportunity, the sheer number and diversity of fossils from the dig site has been truly remarkable.

American Mastodon: (Mammut americanum)
American Mastodon: (Mammut americanum)Courtesy Dantheman9758 at en.wikipedia
Of the nearly 5000 bones and skulls exhumed from the Snowmass fossil site, more than 60 percent were of mastodons (Mammut americanum) representing at least 30 individuals in various stages of life. The other 40 percent of the fauna included mammoths (Mammuthus columbi), camels, horses, giant bison (Bison latifrons) and ground sloths (Megalonyx jeffersonii), otters, muskrats, minks, bats voles, chipmunks, beavers, bats, rabbits, mice, salamanders, frogs, lizards, snakes, fish, and birds, and iridescent beetles. No large carnivore remains were found in the deposits, and human remains were absent as well, although archaeological techniques were used during the dig just in case any were uncovered.

Flora from the prehistoric tundra environment included pollen, green leaves and cones, and tree logs, some with their bark still intact.

So far, age estimates for the deposits range between 43, 000 to 130,000 years old although further dating tests should narrow that down.

The talk included several photos of what Johnson termed “Flintstone moments”, i.e. shots of field workers posing with massive mammoth or mastodon femurs or tibia. And Johnson marveled at the incredible state of preservation of many of the fossils displayed. Some of the bones, he said, still emitted a very strong funk.

In terms of sheer number of bones and ecological data, Snowmastodon ranks up there as probably one of the best high altitude Ice Age ecology sites in the world, and certainly the best mastodon fossil site. A team of researchers at the DMNS lab will spend the next year and a half cleaning, cataloging, and analyzing all the fossils found at the Snowmass dig site, water was to be reintroduced into the reservoir on Oct. 13. Despite the loss of the site, the field crew did a tremendous job in the time they were given to excavate the fossil-rich site. And Kirk Johnson didn’t hide his excitement. In closing his talk, he said “It was one hell of a year!”

FURTHER INFO
The Snowmastodon Project website
Photo set on Flcker

Oct
06
2011

Sputnik 1
Sputnik 1Courtesy NASA
From NASA’s Image of the Day this past Tuesday:

On Oct. 4, 1957, Sputnik 1 successfully launched and entered Earth's orbit. Thus, began the space age. The successful launch shocked the world, giving the former Soviet Union the distinction of putting the first human-made object into space. The word 'Sputnik' originally meant 'fellow traveler,' but has become synonymous with 'satellite' in modern Russian.

This past September 30, almost exactly 54 years later, China launched their first inhabitable space laboratory module, Tiangong-1. The module, a part of a large and ambitious national space program, is the first step in placing a larger modular space station in orbit by 2020.
Combine this effort with Chinese plans to visit the moon and a manned Mars mission, could this be the beginning of a new space race? Personally, I hope so. NASA needs a kick in the pants, and a little “friendly” competition with China could push NASA and its partners in a good way.

Sep
20
2011

There’s been some buzz about the relationship between clouds and climate recently, prompting Andrew Revkin of the New York Times’ Dot Earth blog to get his panties in a twist about the “…over-interpretation of a couple of [scientific] papers…”

What gives? I wanted to know too, so I’ve done a bit – ok, a lot – of research and this is what I can tell you: The heart of the discussion is not whether there is a cloud-climate connection (that’s clear), but rather over what that relationship behaves like. There are at least three possible theories, but before we get to those, let’s review some important background concepts.

Gimme the Basics First

Cloud Formation

First, scientists think of air as units of volume called air masses. Each air mass is identified by its temperature and moisture content. Clouds are basically wet air masses that form when rising air masses expand and cool, causing the moisture in the air to condense. You can see the process in action yourself just by exhaling outside on a cool morning. The Center for Multiscale Modeling of Atmospheric Processes has a webpage to answer your other questions about clouds.

Earth’s Energy Budget
Earth's energy budget: Incoming solar energy is either absorbed (orange) or reflected (yellow).  Outgoing energy is radiated (red).  The arrows show the direction and magnitude of movement where thick arrows signify bigger movements.
Earth's energy budget: Incoming solar energy is either absorbed (orange) or reflected (yellow). Outgoing energy is radiated (red). The arrows show the direction and magnitude of movement where thick arrows signify bigger movements.Courtesy NASA

Energy from the Sun is essential for life on Earth. Let’s pretend the Earth has an “energy budget” where solar energy is like money, absorption is like a deposit, reflection is like a transfer, and radiation is like a withdrawal. It’s not a perfect analogy, but it’ll work for starters: Most of the incoming solar energy (money) is absorbed by (deposited into) the ocean and earth surface, but some is absorbed or reflected (transferred) by the atmosphere and clouds. Most of the outgoing energy is radiated (withdrawn) to space from the atmosphere and clouds. The figure to the right illustrates this process.

The Greenhouse Effect

Thanks to the greenhouse effect, our planet is warm enough to live on. The greenhouse effect occurs within the earth’s energy budget when some of the heat radiating (withdrawing… remember our budget analogy from above?) from the ocean and earth surface is reflected (transferred) back to Earth by greenhouse gases in the atmosphere. Greenhouse gases include carbon dioxide, methane, and water vapor. This National Geographic interactive website entertains the concept.

Climate Change

Climate change is occurring largely because humans are adding more greenhouse gases to the atmosphere. More greenhouse gases in the atmosphere means more heat reflected back to earth and warmer temperatures. Warmer temperatures might sound pretty good to your right now (especially if you live in Minnesota and could see your breath this morning as you walked to school or work), but it’s not. Why? Check out NASA’s really great website on the effects of climate change.

Alright, already. What’s the climate-cloud relationship?

From what I can tell, there are three possible theories about the climate-cloud relationship:

  • Clouds actively drive climate change. This is a linear process where clouds reflect too much heat back to Earth, which increases the average global temperature and causes climate change.
  • Clouds passively blunt climate change. This is a cyclical process where more climate change includes increasing average global temperature, which increases average global evaporation, which creates more clouds. More clouds absorb more heat, keeping the average global temperature from rising even faster and lessening climate change. This slows down (note: it does not stop) the rate of climate change.
  • Clouds passively amplify climate change. This is a cyclical process where more climate change includes increasing the average global temperature, which increases average global evaporation, which creates more clouds. More clouds reflect more heat back to Earth, which raises the average global temperatures and worsens climate change. This speeds up the rate of climate change.
  • So which is it? Probably NOT Theory #1. Maybe Theory #2… or maybe it’s Theory #3? Scientists aren’t quite sure yet, so neither am I, but the evidence is stacking against Theory #1 leaving two possible options. The next big question seems to be surrounding the size of the effects of Theory #2 and Theory #3.

    Using what you just read about cloud formation, the earth’s energy budget, greenhouse gases, and climate change (Woah. You just learned a lot!), what do you think? What’s the climate-cloud relationship?

    If you want, you can read more about what scientists are saying about the climate-cloud relationship here:

Sep
19
2011

According to their website, National Fossil Day is a "celebration organized to promote public awareness and stewardship of fossils, as well as to foster a greater appreciation of their scientific and educational value." This year the celebration is set for October 12, and like last year, I'll probably be doing several posts regarding fossils and the event itself over the next couple of weeks. So with that in mind, here's my first contribution.

Skull of Amia uintaensis (bowfin): Large and well-preserved fossil fish from Fossil Lake deposits shows fine detail, including scales and skin. The full fossil is 49 inches in length. Science Museum of Minnesota collection.
Skull of Amia uintaensis (bowfin): Large and well-preserved fossil fish from Fossil Lake deposits shows fine detail, including scales and skin. The full fossil is 49 inches in length. Science Museum of Minnesota collection.Courtesy Mark Ryan
Tucked in a corner of the Dinosaur and Fossils Gallery here at the Science Museum of Minnesota is a display of fossil fish from the famous Green River Formation. The display offers visitors a look at some of the most well known fossils in the world. Visit a rock shop, natural history store, souvenir shop, or museum just about anywhere and you’ll find fish fossils from the Green River Formation for sale. Literally millions of fossils have been extracted from the formation, so it’s no surprise at all to find some in our paleontology gallery. The display represents only a fraction of the Green River fossils in the Science Museum of Minnesota collection.

Fossil Butte: The butte stands in Fossil Butte National Monument and represents the ancient deposition remains of the center of Fossil Lake in western Wyoming. Limestone and mudstone layers near the top of the butte are rich in fossil fish and other fauna and flora from the Eocene Epoch.
Fossil Butte: The butte stands in Fossil Butte National Monument and represents the ancient deposition remains of the center of Fossil Lake in western Wyoming. Limestone and mudstone layers near the top of the butte are rich in fossil fish and other fauna and flora from the Eocene Epoch.Courtesy Mark Ryan
The sources of this splendid array of extraordinary fossils are the deposits left by three freshwater lakes that existed around 50 million years ago during the Eocene Epoch. These ephemeral bodies of water existed across 17 million years of time, and not all at the same time. Lake Gosiute was the largest in area with a diameter of about 200 miles. Lake Uinta had the most surface area and was the shallowest and existed the longest. Fossil Lake was the smallest and the shortest-lived – but the deepest. The lakes existed in a subtropical environment flush with all sorts of animal life from insects to mammals. More than 20 species of fish populated the waters while crocodiles, turtles and other reptiles basked along lake shores lined with lush forests of palm and fig trees. Birds and bats flew through the sky. Ferns sprouted in the shadowed woodlands of oaks and maples that grew up the slopes of the surrounding mountains. Fir and spruce trees existed in the higher elevations. Fossil remains from this past life are found in all of the basins where the three lakes once existed, but Fossil Lake, as its name implies, produces the most abundant Green River Formation fossils, especially fossil fish.

Fossil Butte: The rich fossil deposits were first discovered by workers for the Union Pacific Railroad.
Fossil Butte: The rich fossil deposits were first discovered by workers for the Union Pacific Railroad.Courtesy Mark Ryan
Railroad workers helping expand the Union Pacific railroad in the mid-1800s first discovered the fossil deposits near the town of Green River, Wyoming. The discovery soon drew the attention of scientists. A geologist named Dr. John Evans collected some of the first fossils from the region in 1856, and Philadelphia paleontologist, Joseph Leidy, soon after described for the first time, Knightia eocaena, the most common fossil fish found in the formation. Edward Drinker Cope, another paleontologist, also collected from the deposits and wrote several important papers starting in 1870.

Heliobastis radiens: A stingray found in the Green River Formation deposits. Science Museum of Minnesota collection.
Heliobastis radiens: A stingray found in the Green River Formation deposits. Science Museum of Minnesota collection.Courtesy Mark Ryan
The fossils on display at the Science Museum include Amia, Knightia, Diplomystus, and the exquisite stingray Heliobatis all preserved in buff-colored slabs consisting of soft lamination of mudstone, limestone, and volcanic ash. There’s also a slab of garfish, and an unlabelled predator named Priscacara next to the large palm frond on the wall near the entrance. Lance Grande (a graduate of the University of Minnesota and paleontologist at the Field Museum of Natural History in Chicago) is considered the leading expert in the fossil remains found in the Green River Formation. His book Paleontology of the Green River Formation (which I referenced heavily for this post) is considered a classic, and contains photos of many specimens found in the Science Museum’s collection.

The two main fish-bearing units in the strata are the 18-inch Layer and the Split-Fish Layer. The formation is considered a laggerstatte (which means storage place) where nearly an entire ecological system is finely preserved in the fossil record. Several lagerstätten exist around the world but the Cambrian-aged Burgess Shale in British Columbia, and the Late Jurassic-aged Solnhofen quarry in Germany are probably the two best known.

Green River Formation: Strata of the famed fossil-rich formation visible in Fossil Butte National Monument. The butte represents deposits from what was once the center of Fossil Lake that existed 50 million years ago during the Eocene Epoch in what is now western Wyoming.
Green River Formation: Strata of the famed fossil-rich formation visible in Fossil Butte National Monument. The butte represents deposits from what was once the center of Fossil Lake that existed 50 million years ago during the Eocene Epoch in what is now western Wyoming.Courtesy Mark Ryan
The deposited remains of what used to be the center of Fossil Lake today form a high butte in western Wyoming that towers a thousand feet above the Visitor Center at Fossil Butte National Monument. The monument was established in 1972 and is located 9 miles west of Kemmerer, Wyoming in the extreme southwestern corner of the state. Despite its somewhat isolated location, it’s well worth going out of your way to see.

Abandoned workers' shelter: Historic Quarry at Fossil Butte National Monument.
Abandoned workers' shelter: Historic Quarry at Fossil Butte National Monument.Courtesy Mark Ryan
My brother Pat and I visited the area on one of our recent geo-trips out west. We first stopped at the Fossil Butte visitor center where, not surprisingly, some extremely rare and high quality Green River fossils were on display, including insects, lizards, turtles, crocodiles, birds, bats, and other mammals. Finely preserved fossils of leaves, cattails, flowers and fruit are also on display. We watched a short film explaining the area and the fossils found there, then Pat and I headed out to a nearby abandoned fossil quarry within the park for a bit of exploration on our own. We parked in the designated lot just off the highway, grabbed our packs and some water, and began our ascent to the Historic Quarry. The climb along the 2.5 mile hiking trail was no picnic – it took about an hour to get to the top, but information signs dot the trail to guide and inform you as you go along. Historic Quarry: Pat Ryan stands level with the fossil-rich 18-Inch Layer located in the abandoned quarry at the top of Fossil Butte.
Historic Quarry: Pat Ryan stands level with the fossil-rich 18-Inch Layer located in the abandoned quarry at the top of Fossil Butte.Courtesy Mark Ryan
And the view of the wide Wyoming landscape is breath-taking. The main trail eventually runs parallel to the butte and along that stretch is an a-frame shack used by workers who excavated the quarry back when it was still operating. Every once in a while we’d come upon a slab of rock that had fallen from the fossil layer above. You could tell this by its buff color, plus one we examined contained the partial remains of the head of a Diplosmystus. The regular hiking trail took us about 600 feet above the highway, but to get to the 18-inch Layer we had to take a spur trail another couple hundred feet up above that.

The 18-Inch Layer exposed at Fossil Butte's Historic Quarry: Fossils from this layer of the Green River Formation are exhibited in museums all over the world.
The 18-Inch Layer exposed at Fossil Butte's Historic Quarry: Fossils from this layer of the Green River Formation are exhibited in museums all over the world.Courtesy Pat Ryan
The 18-inch Layer contains some of the best preserved fossils in the world, and is composed of limestone, oil shale, and volcanic ash. The lacustrine (lake) deposits are laid out in alternating pairs (varves) of light and dark layers each representing an annual cycle of sedimentation. Overall there’s about 4000 years of deposition represented in the layer. Three feet beneath the 18-inch Layer (but not exposed at the Historic Quarry) is a second major fossil unit named the Split Fish Layer (or sandwich layers). This unit is about 6-1/2 feet thick and is so called because when the rock is separated, the fossils themselves split between the top and bottom layers diminishing the quality. When the layers of the 18-inch Layer are separated the fossils are found on only one sheet and protected under a layer of matrix that has to be expertly removed. The Split Fish Layer fossils usually need little if any preparation. According to Fossil Butte museum curator, Arvid Aase, there actually exists several so-called split fish layers, three of them above the 18-inch Layer, along with what are called a mini-fish layer and gastropod bed.

The fossilization process that occurred in the Green River Formation is unique in that the lakes contained a nearly perfect and ideal environment for preserving the delicate remains of its biosphere. A constant rain of calcium carbonate suspended in the waters insured that any dead creature or plant lying on the bottom would be covered and protected from bacteria or the elements. The deeper waters were probably anoxic – meaning lacking oxygen – which aided in further protecting the remains. The fossils are wonderfully preserved, showing fine skeletal details, scales, skin, and even feathers in some cases, all preserved as delicate carbon traces of the once living entity.

Knightia eocaena: The most common genus of fish found in the Green River Formation. Remains are sometimes found in mass mortality layers such as shown here. Science Museum of Minnesota collection.
Knightia eocaena: The most common genus of fish found in the Green River Formation. Remains are sometimes found in mass mortality layers such as shown here. Science Museum of Minnesota collection.Courtesy Mark Ryan
It’s thought that algal blooms sometimes occurred in the lakes during the warmer seasons resulting in mass mortalities of thousands of fish. Large slabs containing more fossil fish than you can count are still being mined from the area.

When I’m working my Tuesday afternoon shift in the Dinosaur and Fossils gallery at the museum I often carry with me a Green River Formation fossil of a leaf to share with visitors. I’ll scratch the matrix with a key or fingernail to allow visitors to experience the oily odor that that emanates from within the rock. Actually the odor is from kerogen a bituminous organic compound in the rock that serves as a source for oil shale, considered a substitute for crude oil. The Green River Formation contains the largest oil shale deposits in the world greatly exceeding the oil reserves of Saudi Arabia.

Be aware that since the Historic Quarry trail is part of Fossil Butte National Monument, collecting of any kind of fossils is prohibited within its borders but fortunately several commercial operations in the area allow you to enter a quarry for a fee and dig up your very own fossils to take home. I’ve never done this so I can’t vouch for any of these commercial dig sites but I am including some links below for some of the more well-known ones in the area.

But even if you can’t make it out to Fossil Butte National Monument this year, you can still come the Science Museum of Minnesota and see our collection, or visit a natural history museum in your own area. Chances are they’ll have some fabulous Green River Formation fossils on display to share with you.

SOURCE and LINKS
GRF info at the Virtual Fossil Museum
Collection and preparation of fossil fish
Historical Geology of the GRF
Ulrich Quarry Fossil Gallery
Warfield Fossil Quarry

Sep
08
2011

The Moon's North Pole
The Moon's North PoleCourtesy NASA/GSFC/Arizona State University
Another awesome image from NASA's Image of the Day.

The Earth's moon has been an endless source of fascination for humanity for thousands of years. When at last Apollo 11 landed on the moon's surface in 1969, the crew found a desolate, lifeless orb, but one which still fascinates scientist and non-scientist alike.

This image of the moon's north polar region was taken by the Lunar Reconnaissance Orbiter Camera, or LROC. One of the primary scientific objectives of LROC is to identify regions of permanent shadow and near-permanent illumination. Since the start of the mission, LROC has acquired thousands of Wide Angle Camera images approaching the north pole. From these images, scientists produced this mosaic, which is composed of 983 images taken over a one month period during northern summer. This mosaic shows the pole when it is best illuminated, regions that are in shadow are candidates for permanent shadow.

Aug
06
2011

Archaeopteryx (Thermopolis specimen): Has the iconic transitional fossil had its feathers ruffled by a recent discovery? Not really.
Archaeopteryx (Thermopolis specimen): Has the iconic transitional fossil had its feathers ruffled by a recent discovery? Not really.Courtesy Mark Ryan
China has been producing some remarkable and groundbreaking dinosaur fossils in recent years that have caused paleontologists to reconsider long-held views. A recently described feathered dinosaur is no different. Xiaotingia zhengi, discovered in the Jurassic shales of the Liaoning Province, has been in the news lately because it supposedly knocked the well-known, so-called proto-bird Archaeopteryx from its perch as the earliest bird.

The study by paleontologist Xu Xing and his colleagues from the Chinese Academy of Sciences in Beijing appears in Nature. Their research, it seems, has determined that Xiaotingia and Archaeopteryx share many features that make the two of them more bird-like dinosaurs than dinosaur-like birds. Do you see the difference there? I guess I do. Anyway, essentially what it means is that Archaeopteryx has been pushed back a little and is just a bit more distantly related to birds than previously thought. The classification places both Xiaotingia and Archaeopteryx in with avian-like carnivorous dinosaurs such as deinonychosaurs, dromaeosaurids, and troodontids. The recent spate of fossils coming out of China can’t help but alter some our old views of the middle to late Jurassic fauna. Many dinosaurs (including non-avian ones) living during that time were equipped with bird-like features: e. g. long arms, feathers, wishbones, etc. They were all over the place.

But all you diehards out there in the Archaeopteryx-is-a-bird camp need not despair just yet. Dr. Xu himself admits that some of the conclusions in the study are based on pretty weak evidence. Archaeopteryx continues to rank as an exceptional transitional fossil (along with Xiaotingia). Its place in the transition has just shifted slightly, that’s all. Further studies and new fossils will no-doubt shake up the branches of the avian family tree again.

References:
Story at Pharyngula
New York Times story

Aug
04
2011

The Moon: According to a recent study, it's two moons in one.
The Moon: According to a recent study, it's two moons in one.Courtesy Mark Ryan
A new study published in Nature proposes that our Moon once had a companion satellite that it eventually accreted in a celestial collision. Planetary scientists, Erik Asphaug, of the University of California, Santa Cruz, and Martin Jutzi of the University of Bern in Switzerland devised computer simulations that show how it could have happened.

According to present lunar origin theory, four and half billion years ago, while the Earth’s system was forming, gravitational forces attracted a Mars-sized object that collided with the early Earth. The collision - more of a glancing blow than a direct hit - tossed terrestrial material into space that coalesced into our Moon. But during the period of coalescence – perhaps for tens of millions of years - a smaller companion moon (about 1/3 the size of the larger moon) would have been visible in Earth’s primitive sky. Geologically speaking, the mini moon’s existence would have been short-lived. The system was unstable, and sooner or later the moonlet’s orbit would decay and it would be pulled either into Earth’s mass or into that of the larger satellite.

Computer simulations set up by Asphaug and Jutzi reconstruct the latter taking place. The researchers propose that the dominant moon was still in a semi-molten state when its smaller companion collided with it at a sub-sonic speed. Being smaller, the doomed moon would have cooled faster and would have been more solidified, but the collision was hardly devastating. It’s low impact speed made it more like a clump of mud being lobbed against a wall. There wasn’t enough force in the collision to punch through, but just enough to make it stick.

More evidence: lunar composition differences

During NASA’s Apollo lunar program in the late 60s and early 70s, astronauts collected several samples of rock from the near side landing sites. The rocks brought back proved rich in potassium (K), rare earth elements (REE) and phosphorus (P) – hence the acronym. These elements, which are scarcer on the Moon’s dark side, crystallize very slowly in cooling magma, and remain molten until the entire mass of magma solidifies. So according to the researchers, when the collision occurred, it was enough to push much of the still molten magma - and the KREEP along with it - to the near side, and leave a pile of mountainous terrain on the far side.

I find this all pretty fascinating. The hypothesis answers several questions that have been puzzling lunar scientists for several years, and fits well into what we observe now. Of course we only see the Moon’s near side. Gravitational forces keep much of the far side hidden from us except via photography and lunar probes (Why that is can be learned here).

SOURCE and LINKS
Story in Scientific American
Story on Weather Space.com
Apollo Lunar Program