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Earth Matters

August Puzzler

August 19th, 2019 by Adam Voiland

Every month on Earth Matters, we offer a puzzling satellite image. The August 2019 puzzler is above. Your challenge is to use the comments section to tell us what we are looking at, where it is, and why it is interesting.

How to answer. You can use a few words or several paragraphs. You might simply tell us the location. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure feature in the image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money or a trip to Mars, but we can promise you credit and glory. Well, maybe just credit. Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. After we post the answer, we will acknowledge the first person to correctly identify the image at the bottom of this blog post. We also may recognize readers who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have shaped the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you would like to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the past few months or if you work in geospatial imaging, please hold your answer for at least a day to give less experienced readers a chance.

Releasing Comments. Savvy readers have solved some puzzlers after a few minutes. To give more people a chance, we may wait 24 to 48 hours before posting comments.

Good luck!

July 2019 Puzzler

July 23rd, 2019 by Kathryn Hansen


Every month on Earth Matters, we offer a puzzling satellite image. This month we are skipping the natural-color satellite image and showing something out of the ordinary. But we assure you: it came from a NASA satellite. Your challenge is to use the comments section to tell us what we are looking at, where it is, and why it is interesting.

How to answer. You can use a few words or several paragraphs. You might simply tell us the location. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure feature in the image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money or a trip to Mars, but we can promise you credit and glory. Well, maybe just credit. Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. After we post the answer, we will acknowledge the first person to correctly identify the image at the bottom of this blog post. We also may recognize readers who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have shaped the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you would like to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the past few months or if you work in geospatial imaging, please hold your answer for at least a day to give less experienced readers a chance.

Releasing Comments. Savvy readers have solved some puzzlers after a few minutes. To give more people a chance, we may wait 24 to 48 hours before posting comments.

Good luck!

Some of our Favorite Apollo and Moon Images

July 19th, 2019 by Kathryn Hansen

Even after 50 years, the day of Apollo 11 Moon landing remains a vivid memory in many minds. But even generations that were not born before July 20, 1969, can appreciate the monumental achievement through numerous historical accounts, video, and photographs. 

Inspection of EO’s 20-year archive turned up numerous occasions on which we have celebrated the Apollo program and the Moon—Earth’s only natural satellite. Below we highlight a few of our favorites. Still hungry for more Earth and Moon imagery? Check out our gallery “Earth From Afar.”

Apollo 11 Launch Pad

On July 16, 1969, Apollo 11 lifted off from launch pad 39A at Cape Canaveral, a headland along Florida’s Atlantic coast. Neil Armstrong, “Buzz” Aldrin, and Michael Collins began their journey to the Moon. On June 9, 2002, the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 satellite captured this true-color image of launch pad 39A and neighboring pad 39B. 

By launching from the east coast of Florida, NASA took advantage of both geography and physics. Rockets could aim eastward and fly over the Atlantic Ocean, far away from heavily populated areas should anything go wrong. And within the continental United States, Florida is closest to the Equator. Launching from a locality close to the Equator enables the rocket to harness Earth’s orbital energy to boost its own trajectory. Read more.

Looking Back from Apollo 11



These two photographs were taken by the crew on their outbound journey from Earth to the Moon. Apollo 11 launched from Cape Canaveral at 9:32 a.m. on July 16, 1969, and these photos were captured that day. The top view shows the full disk of Earth, with bits of California, the Pacific Northwest coast, and Alaska peeking through the cloud cover in a scene otherwise dominated by the Pacific Ocean. The second, closer view shows more of the western United States and Canada, with the Rocky Mountains filling much of the center of the scene and the Arctic ice cap at the top. Read more.

Apollo 11 Landing Site

The Lunar Reconnaissance Orbiter launched on June 18, 2009, and began sending back images of the Moon on June 23. Launched to map the surface of the Moon, LRO was still moving towards its near-surface orbit when it acquired this image of the Apollo 11 landing site. When the orbiter reaches its final orbit, it will image the Moon’s surface at a resolution of 0.5 meters, providing an image that is about two times more detailed than the one shown here. Read more.

A Different Perspective on the Harvest Moon

This image from Apollo 11 shows the Earth rising over the limb of the Moon much as the Harvest Moon does from our planetary perspective. Over the stark, scarred surface of the Moon, the Earth floats in the void of space, a watery jewel swathed in ribbons of clouds.
 
While the Harvest Moon has allowed humans throughout history to coax “just a little more” from the Earth’s bounty before the onset of winter, images of our home from the Moon helped raise awareness of the Earth as a rare (and perhaps unique) planetary ecosystem. The Apollo 11 images provided a global backdrop for the building U.S. environmental movement, including a surge of citizen-led environmental cleanups in the 1960s and 70s, and implementation of key national environmental policies. Read more.

MISR Where on Earth…? Quiz #31

July 12th, 2019 by MISR Outreach Team

The Multi-angle Imaging SpectroRadiometer (MISR) team at NASA is pleased to offer its 31st “Where on Earth?” quiz.

To participate, visit https://climate.nasa.gov/quizzes/misr_quiz_31/

When you visit that page and press “start,” you will be presented with nine multiple-choice questions (one for each of MISR’s nine cameras) about the image above. You may research the answers using any website or reference material you like. You cannot go back to previous questions, so make sure of your answer before proceeding!

The natural color image above was acquired by MISR’s vertical-viewing camera in July 2017 and represents an area about 300 kilometers by 240 kilometers (190 miles by 150 miles). Note that north is not necessarily at the top of the image.

If you answer all of the questions correctly, you will be eligible for a prize. The deadline for entries is July 18, 2019, at 4:00 p.m. Pacific Time. Note – if you try to answer on this blog, you will not be eligible for the prize, so click here to take the quiz.


Watching the 2019 Women’s World Cup from Space

July 2nd, 2019 by Kasha Patel

If you are a fan of soccer (football), June has been an exciting month. Millions of people have been watching the 2019 Women’s World Cup in France, setting a record number for viewers. At least three of those spectators are watching from space.

Onboard the International Space Station, the astronauts have been able to watch from Node 2 as the 24 teams compete for the coveted international championship. Actually, ISS astronauts have 50 computers around the Space Station that can stream the tournament while they continue to work.

Or they can just look out the window.

These pictures were taken by Anne McClain before she returned to Earth on June 24, 2019 at approximately 10:47pm Eastern.

It’s not the best seat in the house, as they are orbiting 250 miles (400 kilometers) above Earth’s surface. They are also moving at 17,500 miles per hour, so they only get about 5 minutes within sight of France.

The Landsat 8 satellite caught a closer look at the action on June 29. The image below shows the Parc Olympique Lyonnais in Décines-Charpieu, France. The stadium fits almost 60,000 people and will host the semifinals and final game.

This image was acquired by Landsat 8 on June 29, 2019. Image obtained via RemotePixel.

At the start of July 2, there were four teams still competing for the Cup: Sweden, the Netherlands, England, and the United States. We looked back into our archives to find images of each of these countries. Can you guess which satellite image below belongs to which country?

Answer
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June puzzler

June 26th, 2019 by Kasha Patel

Update: the answer to the June puzzler has been posted.

Every month on Earth Matters, we offer a puzzling satellite image. The June 2019 puzzler is above. Your challenge is to use the comments section to tell us what we are looking at and why it is interesting.

How to answer. You can use a few words or several paragraphs. You might simply tell us the location. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure feature in the image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money or a trip to Mars, but we can promise you credit and glory. Well, maybe just credit. Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. After we post the answer, we will acknowledge the first person to correctly identify the image at the bottom of this blog post. We also may recognize readers who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have shaped the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you would like to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the past few months or if you work in geospatial imaging, please hold your answer for at least a day to give less experienced readers a chance to play.

Releasing Comments. Savvy readers have solved some puzzlers after a few minutes. To give more people a chance to play, we may wait between 24 to 48 hours before posting comments.

Good luck!

Introducing Landsat Ice Stream (73°36′S, 79°03′W)

June 18th, 2019 by Laura Rocchio, Landsat Communication and Public Engagement Team

The UK’s Antarctic Place-names Committee has agreed that seven ice features in western Antarctica should be named for Earth-observation satellites. One of them is Landsat Ice Steam. 

The new designations were announced on June 7, 2019. The ice features are all located in Western Palmer Land on the southern Antarctic Peninsula.

The seven features ring George VI Sound like pearls on a necklace. The new names, as officially entered into the British Antarctic Territory Gazetteer, are (from west to east): Landsat Ice Steam, ALOS Ice Rumples, Sentinel Ice Stream, GRACE Ice Stream, Envisat Ice Stream, Cryosat Ice Stream, and ERS Ice Stream.

The UK has submitted the new names for the fast-moving ice features to Scientific Committee on Antarctic Research (SCAR), which maintains a gazetteer or registry, of names officially adopted by individual nations. Under the Antarctic Treaty, signatory nations confer on geographic feature names, but each nation’s naming authority formally adopts new names. The U.S. Board on Geographic Names will meet in July and may discuss at that meeting whether the names adopted by the UK also will be adopted by the US. The question of using the term “glacier” for the ice features instead of “ice stream” is also part of each nation’s naming decision.

The new names were proposed by Anna Hogg, a glaciologist with the Center for Polar Observation and Modelling at the University of Leeds. In research published in 2017, Hogg found that glaciers draining from the Antarctic Peninsula were accelerating, thinning, and retreating, with implications for global sea level rise. The fast-moving glaciers that Hogg and colleagues tracked with radar and optical satellite imagery were unnamed. In her paper, the glaciers had to be designated by latitude and longitude.

Anna Hogg, glaciologist from the University of Leeds, proposed naming Antarctic ice features for satellites.

Satellites had enabled Hogg and her team to clock the speed of these nameless ice features—some with rates faster than 1.5 meters/day. In tribute to the spaceborne instruments, Hogg came up with a way to describe the fast-moving ice features more succinctly—name them after the satellites that had helped her understand their behavior.

Hogg proposed to the U.K.’s Antarctic Place-names Committee that the features should be named for Landsat, Sentinel, ALOS PALSAR, ERS, GRACE, CryoSat, and Envisat. She was notified in early June that the committee had agreed to adopt the names, which provide a way to recognize international collaboration, as fifteen space agencies currently collaborate on Antarctic data collection.

“Satellites are the heroes in my science of glaciology,” Hogg told the BBC. “They’ve totally revolutionized our understanding, and I thought it would be brilliant to commemorate them in this way.” 

Naming the glaciers after satellites is also a celebration of data fusion. “Our understanding of ice velocities and ice sheet mass balance has come from putting many different remote sensing data sets together—optical, radar, gravity, and laser altimetry,” said Jeff Masek, the NASA Landsat 9 Project Scientist. “Landsat has been a key piece in assembling that larger puzzle. Naming an ice stream after Landsat is a fitting way to recognize the value of long-term Earth Observation data for measuring changes in Earth’ polar regions.”

Read more from NASA’s Landsat science and outreach team, including the history of Antarctic observation with Landsat. Read more about all of the glaciers and their namesake satellites, as told by the European Space Agency. And read about the island discovered by and named for Landsat, and the woman who discovered it.

Correction, June 27, 2019: SCAR’s role in the Antarctic naming process was incorrectly described in the earlier version of this article. Updates were provided by Dr. Scott Borg, Deputy Assistant Director of the National Science Foundation’s Directorate for Geosciences, and Peter West, the Outreach Program managers for NSF’s Office of Polar Programs, to correctly describe the naming process.

Landsat 8 acquired this image of Mauna Loa on December 20, 2014. The CO2 observatory is located just north of the summit caldera. Credit: NASA Earth Observatory/Landsat 8. Learn more about the image here.

If you follow science news, this will probably sound familiar.

In May 2019, when atmospheric carbon dioxide reached its yearly peak, it set a record. The May average concentration of the greenhouse gas was 414.7 parts per million (ppm), as observed at NOAA’s Mauna Loa Atmospheric Baseline Observatory in Hawaii. That was the highest seasonal peak in 61 years, and the seventh consecutive year with a steep increase, according to NOAA and the Scripps Institution of Oceanography.

The Mauna Loa Observatory has been measuring carbon dioxide since 1958. The remote location (high on a volcano) and scarce vegetation make it a good place to monitor carbon dioxide because it does not have much interference from local sources of the gas. (There are occasional volcanic emissions, but scientists can easily monitor and filter them out.) Mauna Loa is part of a globally distributed network of air sampling sites that measure how much carbon dioxide is in the atmosphere.

Global concentrations of atmospheric carbon dioxide spike every April or May, but in 2019 the spike was bigger than usual. The dashed red line represents the monthly mean values; the black line shows the same data after the seasonal effects have been averaged out. Credit: NOAA. Read more about the image here.

The broad consensus among climate scientists is that increasing concentrations of carbon dioxide in the atmosphere are causing temperatures to warm, sea levels to rise, oceans to grow more acidic, and rainstorms, droughts, floods and fires to become more severe. Here are six less widely known but interesting things to know about carbon dioxide.

The rate of increase is accelerating.

For decades, carbon dioxide concentrations have been increasing every year. In the 1960s, Mauna Loa saw annual increases around 0.8 ppm per year. By the 1980s and 1990s, the growth rate was up to 1.5 ppm year. Now it is above 2 ppm per year. There is “abundant and conclusive evidence” that the acceleration is caused by increased emissions, according to Pieter Tans, senior scientist with NOAA’s Global Monitoring Division.

Credit: NOAA/Scripps Institute of Oceanography. Read more about the chart here.


Scientists have detailed records of atmospheric carbon dioxide that go back 800,000 years.

To understand carbon dioxide variations prior to 1958, scientists rely on ice cores. Researchers have drilled deep into icepack in Antarctica and Greenland and taken samples of ice that are thousands of years old. That old ice contains trapped air bubbles that make it possible for scientists to reconstruct past carbon dioxide levels. The video below, produced by NOAA, illustrates this data set in beautiful detail. Notice how the variations and seasonal “noise” in the observations at short time scales fade away as you look at longer time scales.

CO2 is not evenly distributed.

Satellite observations show carbon dioxide in the air can be somewhat patchy, with high concentrations in some places and lower concentrations in others. For instance, the map below shows carbon dioxide levels for May 2013 in the mid-troposphere, the part of the atmosphere where most weather occurs. At the time there was more carbon dioxide in the northern hemisphere because crops, grasses, and trees hadn’t greened up yet and absorbed some of the gas. The transport and distribution of CO2 throughout the atmosphere is controlled by the jet stream, large weather systems, and other large-scale atmospheric circulations. This patchiness has raised interesting questions about how carbon dioxide is transported from one part of the atmosphere to another—both horizontally and vertically.

The first space-based instrument to independently measure atmospheric carbon dioxide day and night, and under both clear and cloudy conditions over the entire globe, was the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite. Read more about this image here. The OCO-2 satellite, launched in 2014, also makes global measurements of carbon dioxide, and it does so at even lower in the atmosphere than AIRS.

Despite the patchiness, there is still lots of mixing.

In this animation from NASA’s Scientific Visualization Studio, big plumes of carbon dioxide stream from cities in North America, Asia, and Europe. They also rise from areas with active crop fires or wildfires. Yet these plumes quickly get mixed as they rise and encounter high-altitude winds. In the visualization, reds and yellows show regions of higher than average CO2, while blues show regions lower than average. The pulsing of the data is caused by the day/night cycle of plant photosynthesis at the ground. This view highlights carbon dioxide emissions from crop fires in South America and Africa. The carbon dioxide can be transported over long distances, but notice how mountains can block the flow of the gas.

Carbon dioxide peaks during the Northern Hemisphere spring.

You’ll notice that there is a distinct sawtooth pattern in charts that show how carbon dioxide is changing over time. There are peaks and dips in carbon dioxide caused by seasonal changes in vegetation. Plants, trees, and crops absorb carbon dioxide, so seasons with more vegetation have lower levels of the gas. Carbon dioxide concentrations typically peak in April and May because decomposing leaves in forests in the Northern Hemisphere (particularly Canada and Russia) have been adding carbon dioxide to the air all winter, while new leaves have not yet sprouted and absorbed much of the gas. In the chart and maps below, the ebb and flow of the carbon cycle is visible by comparing the monthly changes in carbon dioxide with the globe’s net primary productivity, a measure of how much carbon dioxide vegetation consume during photosynthesis minus the amount they release during respiration. Notice that carbon dioxide dips in Northern Hemisphere summer.

Credit: NASA Earth Observatory. Read more about this image here.

It isn’t just about what is happening in the atmosphere.

Most of Earth’s carbon—about 65,500 billion metric tons—is stored in rocks. The rest resides in the ocean, atmosphere, plants, soil, and fossil fuels. Carbon flows between each reservoir in the carbon cycle, which has slow and fast components. Any change in the cycle that shifts carbon out of one reservoir puts more carbon into other reservoirs. Any changes that put more carbon gases into the atmosphere result in warmer air temperatures. That’s why burning fossil fuels or wildfires are not the only factors determining what happens with atmospheric carbon dioxide. Things like the activity of phytoplankton, the health of the world’s forests, and the ways we change the landscapes through farming or building can play critical roles as well. Read more about the carbon cycle here.

A Bit Less of Excelsior Glacier in Photographs

June 11th, 2019 by Kasha Patel

Excelsior Glacier, June 2019 / Credit: Johnstone Adventure Lodge

In a recent article, we showed satellite imagery of the dramatic retreat of Alaska’s Excelsior Glacier over the past two decades. The glacier has shortened by 30 percent since 1994, primarily due to rising temperatures and calving. What was once ice is now a pool of meltwater called Big Johnstone Lake. Images collected closer to the ground also show dramatic change.

These false-color images show Excelsior Glacier and Big Johnstone Lake on  October 16, 1986 (left) and October 31, 2018 (right), by the Landsat satellites.

In photos taken in 1909 by the U.S. Geological Survey, Excelsior glacier nearly touched the Pacific Ocean, resting on a sliver of forested land. Today, the glacier is separated from the ocean by Big Johnstone Lake, which measures nearly five times the area of New York City’s Central Park.

Excelsior Glacier, 1901 / Credit: U.S.Geological Survey

The following images were taken by staff from the Johnstone Adventure Lodge, which was built near the mouth of the glacier.

The image below shows Excelsior Glacier in 2016 (first) compared to 2018 (second). While the second picture was taken from a farther distance, the absence of icebergs in Big Johnstone Lake stands out.

Excelsior Glacier in 2016 / Credit: Johnstone Adventure Lodge

Excelsior Glacier in 2018 / Credit: Johnstone Adventure Lodge

The following image also shows the complete separation of the glacier into its eastern and western tributaries (as seen in the top 2018 satellite photo). The owners of the lodge have named the right tributary “Roan Glacier.”

Eastern and western tributaries, May 2019 / Credit: Johnstone Adventure Lodge

The following images show changes on Roan Glacier from 2018 to 2019. In 2019, you can see a rogue chunk of ice on right (first image below). According to the owners of the Johnstone Adventure Lodge, the chunk “was certainly not separated in September 2018,” as shown in the second picture.

Roan Glacier in 2019 / Credit: Johnstone Adventure Lodge

Roan Glacier in 2018 / Credit: Johnstone Adventure Lodge

This last image shows 15-20 harbor seals that hang around the glacier. Harbor seals often haul-out on icebergs, so fewer icebergs will likely mean fewer seals as time goes on.

Seals on iceberg, 2018 / Credit: Johnstone Bay

 

Seven million years ago, some truly spectacular creatures roamed the woodlands of East Africa. There was a moose-like giraffe called Shiva’s beast. There were giant buffalo with horns wider than the animals were tall. And the lumbering creatures known as anthracotheres defy easy categorization.

“Whenever I ask colleagues who study anthracotheres how they describe them, they always say: hippo-pig,” laughed Tyler Faith, curator of archaeology at the Natural History Museum of Utah. As for the buffalo: “This was a horn span of 3 meters (10 feet). I mean this was an awesome buffalo.”

Image credit: Slide courtesy of Tyler Faith

These and several dozen variations of more recognizable African megaherbivores — elephants, rhinos, hippos, and giraffes — all went extinct within the past several million years. For decades, archaeologists have pinned the blame on early humans, particularly Homo erectus, a species that emerged 2 million years ago, walked upright, and had a body plan similar to modern humans. Since Homo erectus made stone weapons and was capable of butchering large game, many archaeologists assumed that it hunted Africa’s megaherbivores into extinction — much like the fossil record suggests Homo sapiens (modern humans) did to the large mammals of North and South America some 11,000 years ago.

But nobody rigorously tested whether this “overkill hypothesis” fit with the fossil record. “Speculation had been repeated often enough that it just graduated into fact; it became the truth,” Tyler explained during a recent colloquium at NASA’s Goddard Space Flight Center. To check more rigorously, Tyler and colleagues analyzed fossil assemblages from 101 sites in Eastern Africa.

Image credit: Slide courtesy of Tyler Faith

What they found was a surprise. Megaherbivores began disappearing about 4.6 million years ago — long before Homo erectus came on the scene (1.8 million years ago). And there was no increase in the rate of extinctions even when Homo erectus and butchering showed up in fossil records.

However, when the researchers looked at some key indicators of past environmental conditions, they found one key change — the expansion of grasslands — lined up with the extinctions almost perfectly. Five million years ago, classic open grasslands like today’s Serengeti Plain did not exist in East Africa. Trees and shrubs were a much more dominant part of that African landscape then, explained Tyler.

But as carbon dioxide levels declined, mainly due to orbital variations and changes in the amount of Earth covered by ice, forests retreated and grasslands became dominant. Since many of the megaherbivores fed mainly on woody vegetation, they likely faded away along with their food sources. Meanwhile, other familiar species thrived. The ancestors of wildebeest, hartebeests, Thompson gazelles, oryx, plains zebras, and warthogs — all grazers that live in open habitats — proliferated.

Grasslands dominate northern Tanzania’s Serengeti Plain. The first image shows withered grasslands during a drought. The second image shows the same area during a wetter year. Read more about these images. Credit: NASA Earth Observatory

Faith’s bottom line is that it is time to stop blaming Homo erectus for something they didn’t do. “In the search for ancient hominid impacts on ancient African ecosystems, we must focus our attention on the one species known to be capable of causing them – us, Homo sapiens, over the past 300,000 years,” he said.

Faith’s analysis found that megaherbivore diversity started to decline well before Homo erectus emerged. Image credit: Faith et al.