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NASA Image of the Day: The Rockies from Space

January 10, 2017 Leave a comment
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North America’s Rocky Mountains are seen in this image captured by an astronaut aboard the International Space Station, Jan. 9, 2017. Image courtesy European Space Agency, NASA.

NASA’s Image of the Day for Jan. 10, 2017 is a doozy.

Astronaut Thomas Pesquet of the European Space Agency snapped a photo of North America’s Rocky Mountains from the International Space Station.

When Pesquet shared the photograph on social media, he wrote that “the Rocky mountains are a step too high – even for the clouds to cross.”

 

Wind topples California’s famous Tunnel Tree

January 9, 2017 Leave a comment
pioneers-cabin-tree-circa-1966
This photo of California’s Pioneer’s Cabin Tree, dated 1866, is from the Library of Congress.

The Pioneer Cabin Tree, a California landmark loved by tourists for decades, has been toppled by wind.

A giant sequoia, the huge tree was 150 feet tall. The cutout in its trunk was wide enough to drive cars through and, over the years, many cars did pass under the tree.

Eventually California authorities closed access to cars, but in recent years there has been a hiking trail that leads to it and visitors could still stand in the cutout.

tunnel-tree-photo-by-claudia-beymer
This photo of the base of California’s Tunnel Tree was posted on the Facebook page of the Calaveras Big Trees Association. Image by Claudia Beymer.

Located in Calaveras Big Trees State Park, the Pioneer Cabin Tree – also known as the Tunnel Tree – was estimated to be over 1,000 years old. The large hole in its trunk was carved by owners of the land on which it grew in 1880.

A report in the San Francisco Chronicle explained that there is no way to be sure of the reason why the Tunnel Tree could not withstand the storm that has hit the Golden State in recent days. That storm, the worst in at least a decade, flooded Calaveras Big Trees State Park. The Chronicle explained that the Tunnel Tree’s shallow root system, typical for a sequoia, was likely a factor.

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This photo shows the splintered remains of California’s Tunnel Tree on Jan. 8, 2017. Image courtesy Calaveras Big Trees Association, photo by Jim Allday.

Giant sequoias (Sequoiadendron giganteum), also known as redwoods, are the world’s largest organisms by volume. They can grow to a height of 85 meters and have been known to live for more than 3,500 years.

Now that the Pioneer Cabin Tree has fallen, there are no longer any known living sequoia trees with tunnels through their trunks.

New book by paleontologists Naish and Barrett is a treat for dinosaur fans

December 19, 2016 Leave a comment

naish-and-barrett-dinosaurs-how-they-lived-and-evolved-oct-2016

Those of us who love dinosaurs know that there is something poetic about these animals – the spectacular size of some,  their amazing variety, the mysteries of their long life on this planet . We still feel a thrill when we envision the fantastic beasts and we sometimes find ourselves drifting into a reverie in which we imagine the world under their 140 million-year domination. We can almost see, in our mind’s eye, the graceful long-necked sauropods nibbling the trees and shrubs, the stalking bipedal, sharp-toothed theropods tall and small, and the horned, crested, and armored herbivores wandering the landscape.

Our endless willingness to imagine the great beasts, and our persistent desire to learn more about them, is catered to by a growing variety of mass market books that aim to help us understand their biology and the ecosystems in which they lived. One of the best recent additions to this library, by the British paleontologists Darren Naish (author of the popular Tetrapod Zoology blog) and Paul Barrett (of London’s Natural History Museum), stands out for its depth and its wide-ranging look at dinosaurs’ anatomy, behavior, diversity, and evolution.

The book, Dinosaurs: How They Lived and Evolved, starts with a look at some basic biological principles and the history of dinosaur discoveries. Readers are provided a cogent overview of Earth’s geology and climate during the Mesozoic era, the value of cladistics as a tool to make sense of dinosaur variety, and the place of dinosaurs in the larger group of animals known as archosaurs.

Naish and Barrett then move on to a helpful explanation of the relationships among dinosaur species and a detailed look at dinosaur skeletal systems.

This discussion shines for its skillful and picturesque descriptions of the major dinosaur groups. The authors focus not just on the famous Saurischians and Ornithiscians; they take the reader into a just-deep-enough examination of the clades into which these groups are divided.

In the third section of the book Naish and Barrett shift to an examination of scientists’ current understanding of the deeper aspects of dinosaur biology: their diets, their mating habits, the intricacies of their movement, and their social behaviors. This part of the book is a smorgasbord of insights into how fossils, both trace and body, teach us about the structure of an animal’s life.

Next we are presented with a thorough discussion of modern dinosaurs. Here Naish and Barrett not only delve into the ways in which avian anatomy resembles that of their coelurosaur cousins, but also explain the current understanding of feather origins and the genesis of flight.

In the book’s final section Naish and Barrett, after a review of the impact by an asteroid or comet and its consequences for dinosaurs and their world, highlight another possible contributor to the Mesozoic terminus: active volcanoes around the planet.

The authors explain that, notwithstanding the ecological catastrophe that essentially ended their long reign over the planet’s biosphere (an incident known as the K-Pg event), dinosaurs may have been experiencing both climate change and a loss of diversity at the time it occurred. They take pains to emphasize that, contrary to popular myth, some dinosaurs did survive the end of the Cretaceous period. We know them, of course, as the birds.

Gracing the text are numerous photographs, graphs, and computer-generated reconstructions. Naish and Barrett did not, though, include citations to scientific papers or a bibliography.

Dinosaurs: How They Lived and Evolved is ideal for readers that have some basic familiarity with the biological sciences, though detailed knowledge is not required to enjoy the book.

Published by Smithsonian Books and carrying a cover price of $29.95, the book is a worthy and entertaining read for all of us who continue to be fascinated by the dinosaurs.

NOTE: This reviewer obtained a copy of Dinosaurs: How They Lived and Evolved on loan from the Arapahoe Library District. He was not asked by any publisher or author to prepare this review and has not been compensated for it.

November 2015 is second-warmest in known history, NASA says, as this year stays on track for record warmth

December 19, 2016 Leave a comment

November 2016 was the second-warmest November in recorded history, NASA’s Goddard Institute for Space Studies announced last week, with an average global temperature that was less than one-tenth of a degree Celsius lower than the record-setter of 2015.

Last month was also 0.95 degrees Celsius (1.71 degrees Fahrenheit) warmer than the average November during the years between 1951-1980 and kept Earth on the path to the warmest year the planet has experienced in the 136 years in which consistent weather records have been maintained.

November 2015 was 1.02 degrees Celsius warmer than the mean for the month during that 29-year period.

gistemp-anomaly-nov-2016-courtesy-nasa-giss-schmidt
This graphic shows that November 2016 (shortened line) experienced temperatures well above the norm for the past 136 years.
Graphic courtesy NASA, Goddard Institute for Space Studies; graphic by Gavin Schmidt.

The National Oceanic & Atmospheric Administration announced Monday that, according to its calculations, November 2016 was the fifth-warmest in recorded history. NOAA said that last month’s average global temperature was 0.72 degrees Celsius (1.31 degrees Fahrenheit) above the norm for the month.

NOAA’s assessment of the month’s place in climate history is based on 122 years of records.

As the year approaches its end, there is little doubt that it will be the warmest known in either 122 or 136 years. NOAA’s statement explained that this year’s average temperature to date is 0.94 degrees Celsius (1.69 degrees Fahrenheit) above the mean for the past 122 years, while NASA’s methods indicate that the year-to-date mean temperature is 1.02 degrees Celsius (1.84 degrees Fahrenheit) above that for the period 1951-1980.

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The mean air temperature over Earth’s land and sea surfaces was highest over portions of North America and eastern Asia during November, while central Asia experienced a month that was cooler than usual.
Graphic courtesy NOAA, National Centers for Environmental Information.

Earth’s Arctic region has been the part of the planet where warmth has been most pronounced this year.

NOAA’s 2016 Artic Report Card, which the agency released earlier this month, indicated that the extent of summer sea ice in the region this year was tied with 2007 for the second-lowest since 1979 and that average surface air temperatures there in the year that ended on Sept. 30 were the highest since at least 1900.

The mean air temperature in the Arctic has warmed by 3.5 degrees Celsius (6.3 degrees Fahrenheit) since 1900, a pace that is twice as fast as that experienced by the rest of Earth.

arctic-air-temperatures-oct-2015-sept-2016-courtesy-noaa
The Arctic experienced record warmth between Oct. 2015-Sept. 2016.
Graphic courtesy NOAA.

The continental United States experienced warmer temperatures than normal for the first 11 months of this year from coast-to-coast and from northern border to southern border. This graphic, prepared by the National Centers for Environmental Information, shows that no region in the mainland U.S. experienced an average temperature that is lower than the mean of the past 122 years:

mean-temperature-percentiles-u-s-graphic-courtesy-noaa-national-centers-for-environmental-information
This map shows the deviations from mean temperature across the continental United States during November 2016.
Graphic courtesy NOAA, National Centers for Environmental Information.

NOAA’s new weather satellite reaches geostationary orbit; promises improvement in weather forecasting

December 2, 2016 Leave a comment

goes-r-satellite-logoThe nation’s most advanced weather satellite has reached geostationary orbit and will soon begin helping the National Oceanic & Atmospheric Administration improve weather forecasting.

Capable of imaging the entire western hemisphere of Earth every 15 minutes and the continental United States every five minutes, GOES-16 is expected to improve NOAA’s ability to predict and track thunderstorms, tornadoes, and hurricanes and anticipate solar activity that can impact human activities on Earth.

“The next generation of weather satellites is finally here,” NOAA administrator Kathryn Sullivan said in a statement released after the satellite was launched Nov. 19. “GOES-R is one of the most sophisticated Earth-observing platforms ever devised.”

Sullivan was referring to the generic name for the series of satellites to be launched in the next several years, of which GOES-16 is the first.

The key to GOES-16’s likely impact on meteorology is the satellite’s Advanced Baseline Imager (ABI).

Basically a sophisticated photography instrument, ABI will observe Earth across 16 bands of the electromagnetic spectrum. That is an improvement from weather satellites currently in orbit, which can only make use of five spectral bands.

ABI will also provide a four-fold increase in image resolution and transmit data back to Earth five times faster than is possible with current satellites.

GOES-16 is also equipped with a device that permits the mapping of lightning. The Geostationary Lightning Mapper detects short duration changes in near-infrared radiation, which indicates the presence of atmospheric electrical activity. GLM will operate over North America and South America and the marine areas immediately adjacent to those continents.

A device on the satellite known as Extreme Ultraviolet and X-Ray Irradiance Sensors will detect solar flares, which will in turn assist ground-based agencies in preserving communication and navigation capability when the flares occur.

Another instrument, the Solar Ultraviolet Imager, will allow for observation of other solar activity such as coronal holes and coronal mass ejections. These events can subject satellites and even the International Space Station to risks of increased radiation and disrupt Earth-based communications, navigation, and transmission of electricity.

The GOES-16 satellite is powered by a solar array.

Clifford F. Mass, a professor of atmospheric sciences at the University of Washington in Seattle, said that the potential of the GOES-16 satellite to improve accuracy of forecasts is significant. He explained that the challenge will be to make the most optimal use of the data it provides.

“How do you use the sensor information to create a physically consistent three-dimensional simulation of the atmosphere? That’s something that can be worked on.”

Weather satellites have been crucial to meteorology since the first, TIROS-1, was launched by NASA on April 1, 1960. Since then countries including China, India, Japan, and Russia have joined the United States in building an extensive network of weather satellites in orbit.

tiros-1-image-of-earth-courtesy-nasa
TIROS-1 transmitted the first televised image of Earth on April 1, 1960.
Image courtesy NASA.

Geostationary weather satellites, which permit constant observation of large areas on Earth’s surface, premiered in December 1966 when ATS-1 was sent skyward. In the 1970s NOAA began deployment of the GOES series of satellites, which work in pairs to observe atmospheric conditions from the west coast of Africa to the western Pacific Ocean.

Altogether the U.S. has sent at least 58 weather satellites into orbit.

The first in NOAA’s new Geostationary Operational Environmental Satellite-R series, the 2,800 kilogram-sized GOES-16 is now 35,800 kilometers away from Earth.

GOES-16, which earned its name when it reached stationary orbit above the equator on Nov. 29, is designed for ten years of operation. It will commence observations and data transmission next year, after testing of its instruments is completed.

The launch of GOES-16 does not address an ongoing concern among meteorologists that a gap in weather satellite coverage at the planet’s poles might occur. A 2016 report by the U.S. Government Accountability Office said that the risk that an existing satellite in polar orbit might fail could leave a lapse of coverage before the launch of a new spacecraft, JPSS-1, in March 2017.

 

Drought area in U.S. south now larger than in California

November 30, 2016 Leave a comment

A new map released by the National Drought Mitigation Center presents a shocking image of the country: the area of the south now impacted by drought is larger than the portion of California that is under drought conditions.

Historically anomalous wildfires are currently burning in the Great Smoky Mountains in Tennessee, driven by the dry conditions. The inferno has been driven by high winds, some blowing at velocities in the range of 80-90 miles per hour, and has been burning for four days. The town of Gatlinburg has been significantly damaged by the fires.

Great Smoky Mountains National Park is closed because multiple fires are burning there.

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Wildfires are shown in Great Smoky Mountains National Park, Tennessee, Nov. 29, 2016.
Photo courtesy National Park Service.

Altogether, wildfires are burning across at least 95,000 acres in seven southeastern states. According to the National Interagency Fire Center, there are 15 active conflagrations.

NDMC’s weekly report, released Nov. 23, indicates that only Florida and the coastal southeast are experiencing lower-than-average temperatures. A report by the Southeast Regional Climate Center released earlier in November said that precipitation in many parts of the region is running at 30-70 percent of normal. Describing current conditions in the interior southeast, NDMC said that dryness is ubiquitious:

“[H]undreds (at least 212) new fires have started in the Southeast, with 30 of them classified as large wildfires (100 acres or more), and burn bans were widespread across the region. Streams were at record and near-record low levels. Severe agricultural impacts (stock ponds drying up, winter feed being used to keep cattle alive since fall started) were widespread across the South and Southeast.”

us-drought-conidtions-nov-22-2016
This graphic shows U.S. drought conditions as of Nov. 22, 2016.
Graphic by Richard Heim, graphic courtesy National Centers for Environmental Information, National Oceanic & Atmospheric Administration.

New look at Voyager data indicates that Uranus may have two more moons

October 26, 2016 Leave a comment
uranus-with-rings-and-moons-hubble-space-telescope-courtesy-wikimedia
This Hubble Space Telescope image of Uranus shows the planet surrounded by its four major rings and by 10 of its 27 known satellites. The false-color image was generated by Erich Karkoschka using data obtained by Hubble’s Near Infrared Camera and Multi-Object Spectrometer. Image courtesy NASA, Jet Propulsion Laboratory, Space Telescope Science Institute

Researchers at the University of Idaho say that Uranus, the distant gas giant known for being tipped by 90 degrees, might have two more moons than has previously been thought.

UI physics graduate student Robert O. Chancia and an assistant professor of physics at the university, Dr. Matthew M. Hedman, analyzed data obtained when Voyager 2 transmitted radio waves through Uranus’ rings.

They also looked at changes in the amount of light from distant stars that moves through the planet’s ring system.

Chancia and Hedman found that patterns in the distribution of ring material near the edges of Uranus’ alpha and beta rings vary over time, indicating that small moons may be present.

Dr. Richard G. French, a professor of astrophysics and director of the Whitin Observatory at Wellesley College in Massachusetts, said in an email message that the two UI scientists essentially used a meticulous process of comparison to determine that the pattern was caused by moons.

“Chancia and Hedman compared the wavelike properties from ring profiles taken at slightly different times and different geometries to work backwards to infer the properties of a nearby moon that might produce the satellite wakes,” he wrote.

Hedman pointed out that the results obtained when ground-based receiving stations interpreted the patterns of radio waves after they passed through the two rings shows that the waves were diffracted to varying degrees.

“When you look at this pattern in different places around the ring, the wavelength is different — that points to something changing as you go around the ring,” Hedman said. “There’s something breaking the symmetry.”

The researchers concluded that two possible small moonlets close to Uranus may be the culprits.

“We find for both rings that a moonlet located about 100 [kilometers] exterior to each ring could cause the optical depth variations seen in their occultation scans,” they write in the paper.

French explained that the proposed moons would be quite close to the alpha and beta rings.

“In this case, both moons are slightly exterior to the rings, so they orbit slightly more slowly than the rings themselves,” he wrote in an email message. “As the ring particles pass the moon, their orbits are slightly perturbed, resulting in a ripple pattern within the ring that is detectable as a periodic wavelike structure.”

Those “moonlet wakes” would help to maintain the structure of the Uranian rings, keeping them narrow. The rings are composed of a huge number of tiny particles, which  eventually spread out as collisions between them occur.

Moons near the rings can limit that effect.

French used the example of the planet that may be the solar system’s most famous example of a ring system to explain that a phenomenon called resonance could account for the confining  impact of small moons.

“If you are orbiting Saturn, for example, and you are a little ring particle and you orbit Saturn seven times and the little moon Prometheus six times in that same interval, that’s like getting pushed by the little finger on the swing,” he said. “That little push might be teeny but collectively is powerful. That’s kind of the notion that Matt and his student came up with. Those moons are in the right place to produce this wave pattern inside the rings.”

Chancia said in an email message that he and Hedman are not certain that such moonlet wakes occur in Uranus’ alpha and beta rings.

“We really just wanted to point it out as a possibility, because no one has come up with a universally accepted solution to how these rings are confined,” he wrote. “Anyway, the structures we found look like moonlet wakes.”

If they exist, the two moons would be Uranus’ smallest known and would have a diameter of four to 14 kilometers.

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This diagram shows the Uranian ring scheme. Solid lines depict the rings, while dashed lines indicate the orbital paths of satellites. Graphic courtesy Wikimedia.
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This silhouetted image of the rings of Uranus was taken by the Voyager 2 spacecraft on Jan. 24, 1986. A half-second exposure was made with the wide-angle camera at a distance of 63,300 kilometers (39,300 miles). This image shows the nine originally known rings appearing as dark lines against the brighter clouds of the planet. The most prominent ring, called epsilon, appears at the right; barely visible at the left are the three rings known simply as 4, 5 and 6. The resolution of the image is about nine kilometers (five miles). Image courtesy NASA, Jet Propulsion Laboratory.

The proposed moons, if they are there, were not seen by Voyager 2’s cameras. One reason is that the moons are likely so small that the 1970s-vintage equipment could not detect them.

“[G]iven the small predicted sizes of the ∝ and ß moonlets, a convincing detection may not be possible in the Voyager 2 images,” wrote Chancia and Hedman in their paper.

The two newly-hypothesized Uranian moons may also have a very low albedo,  which would make imaging of them difficult. Like the rings to which they are adjacent, they would not reflect much sunlight because the material from which they are constructed is not especially reflective.

“We know that the Uranian rings are dark because we can compare the amount of  light they block during a stellar occultation – a measure of how much material there is in the rings – with how bright they are in reflected sunlight,” French wrote in an email.

“The answer is that they are quite dark – they are not composed of pure water ice, and it’s likely that they are darkened by dust contamination and perhaps by charged particles in the Uranian environment.”

French explained that the two moons proposed by Chancia and Hedman are likely to exhibit the same characteristic.

“If the satellites are dark, too, then they are stealth objects,” he said. “They are also bloody far away.”

Uranus has 27 known moons, all named for literary characters in William Shakespeare’s plays, and 13 rings that have widths between one and 100 kilometers.

The planet’s ring system was discovered in 1977 by ground-based observers using the Kuiper Airborne Observatory.

Voyager 2 was launched in 1977. Voyager 1, a twin outer solar system probe, was sent into space the same year. The latter has now left the solar system and Voyager 2 is likely to do so within the next few years.

The Chancia and Hedman paper is to be published in The Astronomical Journal and appears online at ArXive.

Update, Oct. 26, 2017, 2:42 pm MDT: The word “part” was changed to the word “particle” in a quote by Professor Richard G. French in order to reflect the correct quotation.

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