([syndicated profile] epod_feed Oct. 17th, 2017 03:01 am)

Yellowstone_Nocni_Pano3_Airglow_1500px (1)

Photographer: Petr Horálek 

Summary Author: Petr Horálek 

Just five days after the Great American Total Solar Eclipse, I was witness to another spectacular astronomical phenomenon. While returning from viewing this eclipse I decided to take a photo of the night sky from Yellowstone National Park and specifically from Grand Prismatic Spring. The Milky Way, at far right, was breathtaking, but what really surprised me were the intense bands of airglow that appeared high over the colorful hot springs. Because the sky was so dark, the airglow was actually visible with the naked eye. Note that the spring itself is the azure colored oval in the mid-ground at right center -- it's responsible for the fog layer (steam fog) lying just above it. Panorama taken on August 26, 2017.

Photo Details: Canon 6D IR Baader modified camera; Samyang 24 mm lens; f2.8, ISO 1000, 28 shots, each with a 15 second exposure; camera mounted on tripod. 

 Guatamala_Panorama1 2048 EPOD (2)

Photographer: Cesar Cantu
Summary Author: Cesar Cantu

Featured above are the volcanoes Agua, at left, and Acatenango at right. Behind Acatenango is  Volcán Fuego. In his compendium of the history of Guatemala City, Domingo Juarros states that the population was unable to prosper because of a formidable torrent of water from Agua (the Volcano of Water) on September 11, 1541. "The torrent brought with it great rocks that destroyed part of the buildings and mistreated the rest."

A second city of Guatemala was founded, today called Antigua, but in 1737 during the prelude to eruptions of Fuego (the Volcano of Fire), strong earthquakes caused significant damage, which again forced the relocation of Guatemala City to its current location. Photo taken from hillside in San Cristóbal, just west of Guatemala City, on July 30, 2017.

Photo Details:  Camera Model: Canon EOS 6D; Lens: EF16-35mm f/2.8L II USM; Focal Length: 35mm; Aperture: ƒ/10.0; Exposure Time: 0.0025 s (1/400); ISO equiv: 100; Software: Adobe Photoshop CS6 (Windows). 
([syndicated profile] epod_feed Oct. 15th, 2017 03:01 am)


Each Sunday we present a notable item from our archives. This EPOD was originally published October 11, 2002.

Provided by: Pam Parker

Summary author: Pam Parker

The gorge of Samaria on the island of Crete, said to be the second longest in Europe after the Gorges du Verdon in southern France, is about 16 km long, starting at an altitude of 1,250 meters and descending to the Mediterranean Sea. The gorge extends from the White Mountains of western Crete to the southern coast. Its narrowest portion, referred to as the iron gate, was an imposing barrier to invading armies. For scale, note the size of the hikers at the bottom of the iron gate.

The gorge was created during the Quaternary Period by a combination of erosional and tectonic processes. Most all of the rock formations in the Samaria Gorge area consist of dolomite. It is now one of the last remaining shelters of the mountain goat of Crete, known as the kri-kri. In addition, it is home to dittany (scientific name Origanum dictamus or Dictamus creticus), a Cretan endemic plant reputed to have therapeutic properties in healing wounds. [Revised September 2017]

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([syndicated profile] epod_feed Oct. 14th, 2017 03:01 am)

River Dream (2)

Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

Photographer: David E. Cartier, Sr 

Summary Authors: David E. Cartier, Sr; Jim Foster

September 2012 Viewer's Choice The photo above featuring a dazzling aurora over Whitehorse, Canada and reflected on the calm waters of the Yukon River was observed the night of September 2/3, 2012. This magnificent chartreuse display was the result of a huge coronal mass ejection (charged particles) released from the Sun's upper atmosphere two days earlier. The aurora pattern was seen to change again and again but the mesmerizing drapes and folds were nearly always aligned with the magnetic field lines of Earth's magnetosphere. With recent episodes of increased solar activity, look for more aurora displays, some visible in the mid-latitudes, during the coming months.

Photo Details: Camera Maker: Canon; Camera Model: Canon EOS 5D; Aperture: f/0.0; Exposure Time: 8.000 s; ISO equiv: 800; Software: Microsoft Windows Live Photo Gallery14.0.8081.709.

([syndicated profile] epod_feed Oct. 13th, 2017 03:01 am)

Picket fence aurora over Osoyoos (2)

Photographer: Debra Ceravolo  

Summary Authors: Debra Ceravolo; Jim Foster

Shown above is a picket fence aurora as observed from near Anarchist Mountain in British Columbia, Canada. The camera is facing north. This type of an aurora, recently referred to as "Steve," shows up below the primary auroral band, 10 to 20 degrees equatorward, extending in a relatively narrow arc for hundreds of miles in an east to west direction. Picket fence auroras can be very localized as photos of the same aurora taken the same night but shot from more northerly latitudes, show it in the opposite direction in the sky. They tend to be quite faint, typically requiring exposures of 10 seconds or longer to bring out their green and red/purple colors. Click here to see a video of this aurora. Photo taken on September 15, 2017, at 10:05 p.m.

Photo Details: Camera Model: Canon EOS 6D; Lens: 20mm F1.4 DG HSM | Art 015; Focal Length: 20mm; Aperture: ƒ/1.4; Exposure Time: 30.000 s; ISO equiv: 800; Software: Adobe Photoshop CC 2015 (Windows). 

([syndicated profile] epod_feed Oct. 12th, 2017 03:01 am)


Photographer: Thomas McGuire

Summary Author
: Thomas McGuire

The 117 National Monuments in the U.S., include historic locations, unique and unspoiled wilderness areas, and even protected marine regions. The U.S. Antiquities Act gives presidents the ability to establish National Monuments. President Obama established the 1.3 million acre Bears Ears National Monument in 2016. This new Monument is mostly a remote wilderness area of southeastern Utah between the Colorado River and agricultural lands about 50 miles (80 km) to the east.

The photo above shows the Bears Ears, two sandstone-crowned buttes, for which this monument was named. Currently, there's a debate concerning the future of Bears Ears and how this land should be best used; it's a classic clash among environmentalists who want to preserve unique wilderness areas, Native Americans who want to protect their sacred lands and local residents who want recreational access and economic benefits in mining and other local jobs. Unfortunately, this debate is likely to be decided by the court system.

Photo Details: Camera Model: Canon EOS REBEL T5; Lens: EF-S18-55mm f/3.5-5.6 IS II; Focal Length: 55mm; Aperture: ƒ/9.0; Exposure Time: 0.0050 s (1/200); ISO equiv: 100; Software: Adobe Photoshop Elements 9.0 Macintosh. 

MonarchandMilkweed_DSCN2717 (1)


Photographer: Rob Sheridan 
Summary Author: Rob Sheridan 

Milkweed species provide critical fuel and shelter in support of the Monarch butterfly’s (Danaus plexippus) miraculous, multigenerational migration to Mexico and back. Adults drink the nectar and lay eggs on the leaves that the larvae consume. But milkweeds face many threats, from habitat loss to invasive parasites. The same milkweed plant pictured in an Earth Science Picture of the Day featured last year, rescued from invasive aphids with a with non-toxic soap insecticide, has grown to maturity and is now playing its critical role in support of Monarch migration.

Pictured is a male Monarch (sex discernible by black spots on lower inner wings) in a meadow near Squantum, Massachusetts, feeding on nectar from the flowers of a common milkweed plant (Asclepias syriaca). This male must have barely escaped a bird predator that left a bite mark on its right anterior wing. Also pictured are wasps feeding (and pollinating) on the same milkweed flowers. Life is tough for the dwindling numbers of persistent Monarchs who hazard hunger and predators to complete their incredible life cycle. Cultivating milkweed may help preserve this inspiring and beautiful animal. Photo taken on July 16, 2017.

Photo Details: Camera Maker: NIKON; Camera Model: COOLPIX P900; Focal Length: 143.0mm (35mm equivalent: 800mm); Aperture: ƒ/5.6; Exposure Time: 0.0020 s (1/500); ISO equiv: 100. 
([syndicated profile] epod_feed Oct. 10th, 2017 03:01 am)

P_Cygni_annotate_EPOD (1)

Photographer: Greg Parker

Summary Author: Greg Parker

I’m particularly interested in ultra deep-red carbon stars and have managed to image quite a number of them over the years. Additionally, I’m also interested in very large, and or very luminous stars, which includes a hypergiant, luminous blue variable (LBV) known as P Cygni, one of the most luminous stars in the galaxy.

As shown above, P Cygni (center) as well as carbon stars BC Cygni (lower left) and SAO 69636 (over the Crescent Nebula) all appear here within the same frame – in the direction of the constellation of Cygnus. P Cygni is so massive and energetic that it’ll exhaust its nuclear fuel relatively quickly. In its short lifetime of just a few million years it will end its life in a supernova explosion.

I was previously aware of BC Cygni but didn't think at the time I made this image that it was particularly important. But of course it was. Coming back to the image several months after taking it and tracking BC Cygni down using a planetarium program, I discovered that it’s a red supergiant star, with a (variable) magnitude near 8.42. The magnitude of BC Cygni varies from +9.0 to + 10.8 over a period of 720+/-40 days. The B-V color index of B C Cygni is a massive 3.64, making it very red indeed, as can be seen in the image. Although it doesn't appear particularly large here, it’s in fact between 1140 and 1230 times larger than our Sun. So if it was placed in the position of our Sun it would actually encompass the orbit of Jupiter.

SAO 69636, also known as R S Cygni, is also a variable star with a magnitude of 7.61 and a B-V index of 3.59. Thus it’s red, though not quite as red as B C Cygni. I find it quite remarkable that three such exceptional stars are present in such a relatively small region of space.

Photo Details: Image was taken using the mini-WASP array at the New Forest Observatory in the U.K., using 18 sub-exposures at 10-minutes per sub, with the image sensor at -20C. 

EiffelTower_Journée pluvieuse à Paris (2)

Photographer: Bertrand Kulik

Summary Authors: Bertrand Kulik; Jim Foster

The photo above shows multiple, miniature views of the Eiffel Tower in Paris as observed through water drops. It was taken, using a macro lens, through the window of my apartment following a rain shower. Because the drops act as simple lenses, the refracted image, the view we see with our eyes, is upside down. I rotated the scene so that it's now right side up. The effect of gravity on the drops gives them a somewhat flattened appearance. Note that the larger and more spherical shaped drops provide the clearest views. Colorful fall foliage can be detected in the foreground of the drop-scapes.

Photo Details: Camera Model: Canon EOS 5D Mark III; Lens: MP-E65mm f/2.8 1-5x Macro Photo; Focal Length: 65.0mm; Aperture: ƒ/11.0; Exposure Time: 0.0040 s (1/250); ISO equiv: 800; Software: Adobe Photoshop CC 2015 (Windows). 

([syndicated profile] epod_feed Oct. 8th, 2017 08:00 am)


Each Sunday we present a notable item from our archives. This EPOD was originally published October 16, 2002.

Provided by: NASA/GSFC, ORBIMAGE, SeaWiFS Project

Summary author: 
Norman Kuring

The above color-coded SeaWiFS satellite image, taken on October 6, 2002, shows upwelling off the California coast. When constant winds blow southward along the west coast of the US, the surface layer of the ocean can be forced away from the coast as a result of the effects of the Earth's rotation and surface friction. As the surface water is pushed offshore, cold, nutrient-rich water upwells from below to replace it. This upwelling facilitates the growth of marine phytoplankton, which is important in nourishing the animal and plant life found along the northern and central California coast. Sensors such as SeaWiFS can detect the effects of this upwelling-related productivity because the chlorophyll-bearing phytoplankton reflects predominantly green light back into space as opposed to the water itself that predominantly reflects blue wavelengths back to space. The upwelling region is color-coded to show chlorophyll concentrations - highest concentrations are shown in red and lowest concentrations are shown in blue. Land and cloud portions of the image are presented in quasi-natural color. [Revised September 2017]

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([syndicated profile] epod_feed Oct. 7th, 2017 03:01 am)

Mount Baker from Above - IMAG0564

Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

Photographer: Stu Witmer

Summary Author: Stu Witmer

August 2012 Viewer's ChoiceThe stratovolcano Mount Baker (10,778 ft or 3,285 m) is one of a long string of volcanoes along the West Coast of North America. Most people see the mountain from the south or west. From that point of view, the mountain’s flat top is unmistakable. The fact that it stands far above the surrounding terrain adds to its distinction. From this photo, taken from an airliner at 29,000 ft (8,840 m), you don’t notice either of these things but you can’t fail to miss all the white stuff. The Cascades have among the heaviest annual snowfalls anywhere on Earth and Mount Baker carries a higher volume of snow and ice than all the Cascade volcanoes put together, excluding Mount Rainier. During the winter of 1998-1999 Mount Baker set what's believed to be a world record with 1,140 in (2,896 cm) of snowfall. As of July 2012, Mount Baker’s glaciers cover an area of 14.9 sq mi (38.6 sq km). Studies of nine glaciers on the mountain show that individual glaciers have retreated from 788 ft (240 m) to 1,706 ft (520 m) between 1984 and 2009. Colfax Peak and the jagged Lincoln Peak are seen on the left of Baker’s volcanic cone. Baker is one of the youngest of the Cascade Volcanoes and the cone seen here is probably less than 30,000 years old. The mountain is named for Joseph Baker an officer serving with George Vancouver on an exploring expedition in 1792. The local Nooksack Indians have a descriptive name for it: Koma Kulshan or White Steep Mountain. Photo taken September 2, 2011.

Photo Details: Camera Maker: HTC; Camera Model: PC36100; Focal Length: 4.92mm; ISO equiv: 121; Software: GIMP 2.

Stcruz662c_24july17 (1)

Photographer: Ray Boren 

Summary Author: Ray Boren 

The very name of Natural Bridges State Beach, in Santa Cruz, California, is a clue that geology happens — sometimes surprisingly quickly. Despite the plural use of bridges, only one arch is visible at this site today. In the photograph here, taken on June 24, 2017, that lone arch reaches out into the Pacific Ocean, beyond children playing in the surf. Note that as other wading beach-goers try to find a perch on the stony stack’s edges a flock of California brown pelicans also happens to be flying by.

In the course of a long human lifetime — between 1906 and 1980 — the natural arcs that gave this location its name went from three windows, in a single peninsular finger of marine Santa Cruz Mudstone, to just one. A historic photo in the Special Collections at the University of California at Santa Cruz shows the formation in about 1900. It is presented together with other photos on a Mobile Ranger Web page, accessible here.

Santa Cruz Mudstone consists of fine-grained silts, clays and single-celled plankton called diatoms, which settled on an offshore continental shelf or slope during the late Miocene, 7-9 million years ago. The thick, yellowish-brown siliceous and organic layers cemented and lithified into rock, and have been subsequently folded and faulted and tilted and twisted by tectonic stresses. The mudstone resists the pounding oceanic waves, but time and erosion took the outermost of the triplet bridges in 1905 or 1906, leaving just a temporary stump, historians say. Then, during a storm on January 10, 1980, the innermost bridge also collapsed, leaving today’s lone opening. And someday, as Alexander Weiss observed in his “Ode to an Arch,” penned soon after that 1980 tumble, the remaining window, too, will vanish:

For through erosion it was born

And through erosion it would die

And such a death one does not mourn

One merely says goodbye.

Photo Details: Camera Model: NIKON D3200; Lens: Tokina AT-X 124 AF PRO DX II (AF 12-24mm f/4); Focal Length: 15mm (35mm equivalent: 22mm); Aperture: ƒ/11.0; Exposure Time: 0.0020 s (1/500); ISO equiv: 280. 

([syndicated profile] epod_feed Oct. 5th, 2017 03:01 am)



Photographer: Patti Weeks

Summary Author: Patti Weeks 

Kudzu (of the genus Pueraria) is an iconic image of the southeastern United States landscape. It's a non-native climbing vine from Asia known for its fast growth and propensity to blanket everything in its path. Once established in the countryside, it can cover fences, power lines, abandoned buildings, and smother entire trees. It kills the flora it engulfs by heavy shading.

Kudzu was introduced to America at the Japanese pavilion in the 1876 World’s Fair Centennial Exhibition in Philadelphia. Shortly after the Fair, it became an ornamental and shading plant for porches and courtyards of southern homes. Then, with government support, it was used in the 1930s by farmers as erosion control and livestock feed. It was also planted by railroad and highway developers to prevent erosion on hillsides. Left unattended, the hearty kudzu continued to creep further into the nearby countryside—and it is still growing today. Kudzu eventually became more of a scourge than an asset and is now classified as a noxious weed in 13 states.

Kudzu is difficult to control with its deep root system and its growth of up to a foot (30 cm) a day. A single older root can be as deep as 12 feet (3.7 m) and weigh up to 300 pounds. Vines grow in all directions and as they spread along the soil they will form new root crowns as independent plants. Mature stands can create mats up to 8 feet (2.4 m) thick.

Contrary to the popular perception that kudzu has taken over the South it, in fact, prefers sunny locations, such as the embankments of roadways and railways and will not invade an adjacent shady forest. To travelers who espy the conspicuous vine from their cars or trains, it appears to be everywhere. It's extremely aggressive but is not the sinister threat to humanity as the perpetuated myth may make it seem. People don’t have to keep their windows closed at night!

The top photo captured kudzu in the median of Highway 49 in the Mississippi Delta, several miles southeast of Clarksdale, Mississippi, on June 22, 2017. The bottom photo shows kudzu-covered trees and its broad mat stretched across a dry creek bed on a country road in southwestern North Carolina near Chimney Rock on August 20, 2017. 

Photo Details: Top - Camera Model: SONY DSC-HX400V; Lens: 4.3-215 mm ƒ/2.8-6.3; Focal Length: 5.24 mm; Aperture: ƒ/3.2; Exposure Time: 1/250; ISO 80. Bottom: same except - Focal Length: 12.58 mm; Aperture: f/3.5; Exposure Time: 1/500; ISO 80. 

([syndicated profile] epod_feed Oct. 4th, 2017 03:01 am)



Photographer: Jim Bucko 

Summary Author: Jim Bucko 

Featured above are two photos showing the Newgrange tomb or temple in the Boyne Valley of Ireland. It dates back to approximately 3200 BC. The mound is 280 ft (86 m) in diameter, about 44 ft (13.5 m) high and is encircled by 97 kerbstones. A 62 ft (19 m) long passage, leading to a cruciform chamber (3 alcoves), is illuminated by the Sun at dawn on the winter solstice. Additionally, there's an entrance stone at the opening of the passage bearing petroglyphs (bottom photo). Some of the stones on the lower wall have petroglyphs as well. Note that it's not known what these symbols mean.

There are several similarities here to the temples I saw when I visited the Mediterranean islands of Malta and Gozo earlier this year. Not only are some of the architectural features similar, like the passage and cruciform chamber, many of the petroglyph designs are similar, particularly the spirals and circles.

Photo Details: Top - Camera Model: Canon PowerShot SD1200 IS; Focal Length: 6.2mm; Aperture: ƒ/8.0; Exposure Time: 0.0080 s (1/125); ISO equiv: 80. Bottom - same except: Aperture: ƒ/2.8; Exposure Time: 0.0040 s (1/250).