Yamzho Yumco (Sacred Swan) Lake is one of the three largest sacred lakes in Tibet. It is surrounded by snow-capped mountains and is highly crenellated with many bays and inlets. The lake is home to the Samding monastery which is headed by a female reincarnation, Samding Dorje Phagmo. The image covers an area of 49.8km by 60km. Aster images map and monitor the changing surface of our planet, such as glacial advances and retreats; potentially active volcanoes; crop stress; cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.
This distinctive checkerboard pattern lies alongside the Priest river in northern Idaho. The photograph was taken just before sunset, so some mountainsides glow while others are covered in long shadows because of the low sun angle. The squares appear to be the result of forest management. The land here is now managed for wildlife and for timber harvesting. The white patches reflect areas with younger, smaller trees, where winter snow cover shows up brightly to the astronauts. Dark green-brown squares are parcels of denser, intact forest. The checkerboard is used as a method of maintaining the sustainability of forested tracts while still enabling a harvest of trees. The Priest river, winding through the scene, is bordered on both sides by a forest buffer that can serve as a natural filtration system to protect water quality. For nearly a century, the river was used to transport logs. Its function changed in 1968 when the river’s main stem was added to a list of “wild and scenic rivers” in order to preserve its “outstanding natural, cultural, and recreational values in a free-flowing condition for the enjoyment of present and future generations”.
According to weather forecasts, Denmark was in line to be hit with strong winds, sub-zero temperatures, and precipitation from 4-7 January. Heavy flooding was expected in parts of the west coast, while Jutland and Bornholm were in line for sleet and snow. In this image, a layer of white lies over northern Jutland in the north-west, and additional streaks of snow can be seen as far south as Germany. A bank of cloud, likely part of the storm system, hangs over the blue waters of Skagerrak – a strait that lies between the south-east coast of Norway, the south-west coast of Sweden, and Denmark’s Jutland peninsula.
How do you deliver supplies to one of the most remote research stations on Earth? Put the equipment and food on skis and pull them by tractor across the ice and snow in a long caravan. The convoy of supplies can be seen on the 1,000km trek from Dumont d’Urville on the Antarctic coast to Concordia research station. The traverse across Antarctica takes 10 days, climbing more than 3,000 metres to reach Concordia’s plateau. Pulled by heavy-duty tractors, the caravans carry up to 300 tonnes of fuel, food and heavy equipment in 300 metre-long convoys organised by France’s IPEV polar institute. Once at Concordia, three days are spent unpacking and preparing for the return trip to the coast, which generally takes two days less because it is downhill most of the way.
Concordia sits on a plateau 3,200 metres above sea level. Temperatures can drop to –80C in winter when the sun does not rise above the horizon, forcing the crew to live in isolation without sunlight for four months of the year. For ESA, the isolation and extreme weather offer interesting parallels with spaceflight. Each year an ESA-sponsored medical doctor joins the crew of the Italian–French station to monitor and run experiments.
Snow-covered St Petersburg on the Neva bay may appear to be in black and white, but it is in fact in true colour – the snow and lack of vegetation during winter lend very little colour to the scene. One of the most prominent features is the large area of ice and snow covering the water.
Looking closer to the lower-central part of the image, we can see where icebreakers have created a straight route to and from St Petersburg’s port. The boats leaving the port continue west following a channel through the St Petersburg dam south of Kotlin Island and into the Gulf of Finland. There are five other breaks along the northern stretch of the dam without ice because the flowing water prevented freezing. The 25km-long dam complex protects the city from storm surges and also acts as a bridge from the mainland to Kotlin Island. On the right, the Neva flows through the centre of St Petersburg – Russia’s second largest city. Sometimes dubbed the Venice of the North for its numerous canals and more than 400 bridges, the city dates back to 1703 and was built by Tsar Peter the Great. Today, St Petersburg is a Unesco world heritage site.
Milky, grey smog shrouds many of the valleys and lowlands of eastern China. The brightest, whiter areas (left, top, and bottom edges) are likely clouds or fog. Outbreaks of smog and haze, like this, tend to occur during the winter because of temperature inversions. Air naturally cools as it rises in altitude; but during an inversion, warm air masses settle over a layer of cool air near the surface. The warm air acts like a lid and traps gases and pollutants near the surface, especially in basins and valleys.
Many of the particles in the haze are sulphate aerosols produced by burning coal. Coal supplies a majority of China’s energy, and the northern half of the country uses coal widely to heat buildings in the winter. In addition to emitting carbon dioxide, coal fires release sulphur dioxide, a gas that combines with water vapour to make small droplets and crystals of sulphuric acid and other sulphates, which can be detrimental to health.
Several days of heavy rainfall swamped much of southern Thailand in January. While monsoon-related floods are common in the region, the wet season usually ends in November. Much of the tan and yellow colour on the landscape is sediment-laden flood water near the Pra river. For comparison, the second image shows the same area on 2 February 2014, when waters were lower. The rainfall was some of the most severe to hit Thailand in three decades, according to Thai authorities. More than 300,000 homes were affected, and damage to infrastructure was widespread. At least 36 people died.
A photograph of a variety of agricultural patterns near an oasis in eastern Libya, one of the most remote places in Africa, more than 900km (560 miles) from the nearest major city. The cluster of buildings, roads, and small farming operations near the top of the photo is the town of Al Jawf. Each farming pattern in the image is related to different irrigation methods. The honeycombs in the centre are what remain of the first planned farming method in the Libyan desert, implemented about 1970. The large circles (about 1km wide) of centre-pivot irrigation systems (lower left) replaced the honeycombs in order to conserve water. The grid system (upper left) is perhaps one of the oldest known to planned agriculture, but it is still used alongside the more modern patterns.
Near Al Jawf, the oasis is covered in lush green gardens and palm trees that survive due to pumping from the largest known fossil water aquifer in the world: the Nubian Sandstone Aquifer. More than 20,000 years ago, the Saharan landscape was wet and heavy rainfall continuously refilled the aquifer. Today the region receives less than 0.1in of rain a year, making this aquifer a non-renewable resource. An agreement was recently hashed out between Libya and the UN Food and Agriculture Organisation to improve food security in the region by developing the country’s agriculture industry. This means the use of fossil water will continue, and the agricultural patterns we see today are likely to survive for years to come.
The winter landscape in Brussels complements the red clay roofs of the historic Quartier des Squares (centre) and the white tops of the Royal Museum of the Armed Forces (centre right).
An area over the western end of the state of Texas is rather devoid of colour owing to the landscape’s sparse vegetation cover. Some colour appears along the rivers and streams where plants thrive more easily. In the upper left, large circles of agriculture from central-pivot irrigation systems appear green. Centre left, one area appears orange where the land may have a different mineral content. On the upper-right side, we can see a cluster of hills of the Sierra Madera crater, formed less than 100m years ago when a meteorite hit Earth. In the lower-right corner, we can see a network of oil wells connected via a spiderweb-like structure of supply roads. Underground oil reservoirs usually stretch across large areas, and multiple wells are positioned over the reservoirs to best exploit the natural resource. Texas is the top crude oil-producing state in the US, accounting for about a third of the country’s output.
A crack in the Larsen-C ice shelf on the Antarctic peninsula first appeared several years ago, but recently it has been lengthening faster than before. The satellites show that the fissure has opened about 60km since January last year. And, since the beginning of this January, it has split a further 20km so that the 350 metre-thick shelf is held only by a thread. The crack now extends around 175km. When the ice shelf calves, this iceberg will be one of the largest ever recorded. Exactly how long this will take is difficult to predict. The neighbouring Larsen-A and Larsen-B ice shelves suffered a similar fate with dramatic calving events in 1995 and 2002, respectively. These ice shelves are important because they act as buttresses, holding back the ice that flows towards the sea.
This panorama shows nearly the full length of Lake Powell, the reservoir on the Colorado river in southern Utah and northern Arizona. At full capacity, the reservoir impounds 24,322,000 acre-feet of water, a vast amount that is used to generate and supply water to several western states, while also aiding in flood control for the region. It is the second largest reservoir by maximum water capacity in the US (behind Lake Mead).
Green forests indicate two high places in the image that are cooler and receive more rain than the dry, low country surrounding the lake. The isolated Navajo mountain is a sacred mountain of the Native American Navajo tribe and rises to 3,154 metres (10,348ft). The long, narrow Kaiparowits Plateau rises nearly 1,200 metres from Lake Powell to an elevation of more than 2,300 metres. More than 80km (50 miles) long, the plateau gives a sense of horizontal scale. The region draws nearly 2 million people every year, even though it is remote and has few roads. Most of the area in view is protected as part of the Glen Canyon national recreation area and the Grand Staircase-Escalante national monument – the largest area of protected land in a US national monument.
The Moroccan city of Nador is sheltered from the Mediterranean by Mar Chica, a sandy saltwater lagoon. Mar Chica has a shallow maximum depth – only 8 metres – allowing us to see the ebb and flow of tides clearly from space.
In Africa’s Danakil depression (or Afar triangle) three tectonic plates are tearing themselves apart in spectacular fashion. As the plates separate, several active volcanoes have emerged along the seams. One of the most active is Erta Ale, a shield volcano near the Ethiopian and Eritrean border. It is known as the “smoking mountain” and the “gateway to hell” in the Afar language. Erta Ale has a long-lived lava lake that has gurgled and spattered in its caldera for decades, but the most recent bout of activity involves the south-east flank of the gently sloping mountain. According to reports posted by Volcano Discovery, new fissures opened up on 21 January, about 7km (4 miles) from the summit caldera, spilling large amounts of lava. Meanwhile, at least one of the lava lakes has experienced large changes in the level of its lava that have led to overflows and intense spattering. Infrared hotspots representing two distinct lava flows are visible. Plumes of volcanic gases and steam drift from the lava lakes.
Oil rigs in the Gulf of Mexico gather oil and natural gas from beneath the seafloor of the Bahía de Campeche, located along the southern margin of the gulf, just west of the Yucatán Peninsula.
In the early 1970s, oil exploration turned up vast reservoirs of oil and gas in the region and offshore oil drilling continues today, with signs of the activity visible from space.
Crude oil often contains natural gas. When buried deep underground, the natural gas stays dissolved in the oil due to high pressure. But as the oil nears the surface and pressure decreases, flammable gas (mostly methane) bubbles out. Many oil rig operators try to preserve the gas for use by customers, but depending on the situation, some operators may instead choose to burn it. Sometimes the gas is burned because it is contaminated with mud or other substances. In other cases, there may be no other way to dispose of it quickly and safely.
Wildfires ravaged hundreds of thousands of acres in southern and central Chile during the first month of 2017. According to a CNN report, President Michelle Bachelet said: “We have never seen anything on this scale, never in the history of Chile.” The wildfires killed at least 11 people, destroyed thousands of homes and consumed an area about three times the size of New York City, according to several media accounts. The flames destroyed a town called Santa Olga, displacing about 6,000 people, burning about 1,000 homes and destroying the town’s kindergarten. The red hotspots, accompanied by thick and billowing smoke, show the heat from actively burning fires. The town of Santa Olga was near the southern end of the chain of fires.
Cambodia has one of the fastest rates of forest loss in the world. In broad swaths of the country, densely forested landscapes – even those in protected areas – have been clear-cut over the past decade, mostly for rubber plantations and timber.
Scientists from the University of Maryland and the World Resources Institute’s global forest watch have been using Landsat satellite data to track the rate of forest loss on a global scale. Though other countries have lost more acres in recent years, Cambodia stands out for how rapidly its forests are being cleared. Between 2001 and 2014, the annual forest loss rate in Cambodia increased by 14.4%. Put another way, the country lost a total of 5,560 square miles of forest. Other countries with accelerating rates of forest loss include Sierra Leone (12.6%), Madagascar (8.3%), Uruguay (8.1%), and Paraguay (7.7%).
The transformation of Cambodia’s landscape has been profound. The first image, taken on 31 December 2000, shows intact forest near the border of the Kampong Thom and Kampong Cham provinces. On 30 October 2015, the second image shows much of the forest has been replaced by a grid-like pattern of roads and fields and by large-scale rubber plantations. Clear-cutting has also chewed away at the edges of densely forested areas (dark green) and replaced them with exposed soil, croplands, and mixed forests (brown and light green).
Researchers working with Landsat data have demonstrated that changes in global rubber prices and a surge of land-concession deals have played key roles in accelerating Cambodia’s rate of deforestation. Concession lands are leased by the Cambodian government to domestic and foreign investors for agriculture, timber production, and other uses. Researchers found that the rate of forest loss within concession lands was anywhere from 29% to 105% higher than in comparable lands outside the concessions.
If you ever fly over the High Atlas range in Morocco, look down. You will be treated to a visual spectacle of massive layers of colourful rock crumpled up like pieces of paper. Sharp ridges bobbing and weaving their way across the desert. Splotches of black basalt spilled by ancient volcanoes. Zebra-like layered outcrops of rock jutting from valleys at odd angles. The High Atlas Mountains extend in a north-easterly direction from Morocco’s Atlantic coast (near Agadir) for hundreds of miles inland toward the Algerian border. The western portion of the range is home to its tallest mountains, with peaks that stand above 4,000 metres.
The Atlas Mountains were shaped by geological processes at work over hundreds of millions of years. One key step occurred in the early Jurassic period (201m to 174m years ago), when many of the world’s continents were still bunched closely together after the breakup of the supercontinent Pangea. This part of Morocco fell within the African plate, near a boundary with the Eurasian and North American plates. As the three plates separated, the crust thinned so much that a tear opened up and formed a rift valley that eventually filled with ocean water. As the crust thinned and the rift opened up, large blocks of Earth’s crust dropped downward, creating broad valleys known as grabens. Grabens have elevated blocks at their edges called horsts that became fault-block mountains. These mountains were pushed up even higher during a later phase of intense mountain building in the Cenozoic (66m years to present), spurred by the collision of African and Eurasian tectonic plates.
A display of hole-punch clouds over eastern China, visible on 28 December 2016. This strange phenomenon results from a combination of cold temperatures, air traffic, and atmospheric instability. If you were to look from below, it would appear as if part of the cloud were falling out of the sky, which is actually what’s happening. The mid-level clouds are initially composed of liquid drops at a super-cooled temperature below 0C. As an airplane passes through the cloud, it creates a disturbance that triggers freezing. Ice particles then quickly grow in the place of the water droplets. Eventually the ice crystals in these patches of clouds grow large enough that they literally fall out of the sky – earning hole-punch clouds their alternate name: fallstreak holes. Falling crystals are often visible in the centre of the voids. The formations in this image are less like holes and more linear, like long canals. Whether the void takes on a circular or linear shape depends on differences such as cloud thickness, wind shear, and air temperature. Hole-punch and canal clouds often occur in the vicinity of an airport.
In the Nevada desert, the pioneering artist Michael Heizer completes his colossal life’s work.
