Creature Aurora Over Norway

Explanation: It was Halloween and the sky looked like a creature. Exactly which creature, the astrophotographer was unsure (but possibly you can suggest one). Exactly what caused the eerie apparition was sure: one of the best auroral displays in recent memory. This spectacular aurora had an unusually high degree of detail. Pictured above, the vivid green and purple auroral colors are caused by high atmospheric oxygen and hydrogen reacting to a burst of incoming electrons. Birch trees in Tromsø, Norway formed an also eerie foreground. Many other photogenic auroras have been triggered by recent energetic flares on the Sun.

Solar Eclipse from Uganda

Explanation: The Sun's disk was totally eclipsed for a brief 20 seconds as the Moon's dark umbral shadow raced across Pokwero in northwestern Uganda on November 3rd. So this sharp telescopic view of totality in clear skies from the central African locale was much sought after by eclipse watchers. In the inspiring celestial scene the Moon just covers the overwhelmingly bright photosphere, the lower, normally visible layer of the Sun's atmosphere. Extending beyond the photosphere, the reddish hydrogen alpha glow of the solar chromosphere outlines the lunar silhouette, fading into the Sun's tenuous, hot, outer atmosphere or corona. Planet-sized prominences reaching beyond the limb of the active Sun adorn the edges of the silhouette, including a cloud of glowing plasma separated from the chromosphere near the 1 o'clock position.

In the shadow of Saturn

Explanation: In the shadow of Saturn, unexpected wonders appear. The robotic Cassini spacecraft now orbiting Saturn drifted in giant planet's shadow earlier this year and looked back toward the eclipsed Sun. Cassini saw a unique and celebrated view. First, the night side of Saturn is seen to be partly lit by light reflected from its own majestic ring system. Next, Saturn's expansive ring system appears as majestic as always even from this odd angle. Ring particles, many glowing only as irregular crescents, slightly scatter sunlight toward Cassini in this natural color image. Several moons and ring features are also discernible. Appearing quite prominently is Saturn's E ring, the ring created by the unusual ice-fountains of the moon Enceladus and the outermost ring visible above. To the upper left, far in the distance, are the planets Mars and Venus. To the lower right, however, is perhaps the most wondrous spectacle of all: the almost invisible, nearly ignorable, pale blue dot of Earth.

One Special Day in the Life of Planet Earth

The cameras on NASA's Cassini spacecraft captured this rare look at Earth and its moon from Saturn orbit on July 19, 2013. Taken while performing a large wide-angle mosaic of the entire Saturn ring system, narrow-angle camera images were deliberately inserted into the sequence in order to image Earth and its moon. This is the second time that Cassini has imaged Earth from within Saturn's shadow, and only the third time ever that our planet has been imaged from the outer solar system.

Earth is the blue point of light on the left; the moon is fainter, white, and on the right. Both are seen here through the faint, diffuse E ring of Saturn. Earth was brighter than the estimated brightness used to calculate the narrow-angle camera exposure times. Hence, information derived from the wide-angle camera images was used to process this color composite.

Both Earth and the moon have been increased in brightness for easy visibility; in addition, brightness of the moon has been increased relative to Earth, and the brightness of the E ring has been increased as well.

Images taken using red, green and blue spectral filters were combined to create this natural color view. (The accompanying wide angle frame can be found at PIA17171.) The images were obtained by the Cassini spacecraft cameras on July 19, 2013 at a distance of approximately 898.414 million miles (1.445858 billion kilometers) from Earth. Image scale on the Earth is 5,382 miles (8,662 kilometers) per pixel. The illuminated areas of neither Earth nor the moon are resolved here. Consequently, the size of each "dot" is the same size that a point of light of comparable brightness would have in the narrow angle camera.

A close-up view of Earth and moon, magnified by a factor of five is available at PIA17170.

The first image of Earth captured from the outer solar system was taken by NASA's Voyager 1 in 1990 and famously titled "Pale Blue Dot" (PIA00452). Sixteen years later, in 2006, Cassini imaged the Earth in the stunning and unique mosaic of Saturn called "In Saturn's Shadow-The Pale Blue Dot" (PIA08329). And, seven years further along, Cassini did it again in a coordinated event that became the first time that Earth's inhabitants knew in advance that they were being imaged from nearly a billion miles (nearly 1.5 billion kilometers) away. It was the also the first time that Cassini's highest-resolution camera was employed so that the Earth and its moon could be captured as two distinct targets.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

 

What's that below the Milky Way?

Explanation: What's that below the Milky Way? First, across the top of the above image, lies the faint band that is our planet's sideways view of the central disk of our home Milky Way Galaxy. The Milky Way band can be seen most clear nights from just about anywhere on Earth with a dark sky. What lies beneath is, by comparison, is a much less common sight. It is the striking peak of Castildetierra, a rock formation located in Bardenas Reales, a natural badlands in northeast Spain. Standing 50 meters tall, the rock spire includes clay and sandstone left over from thousands of years of erosion by wind and water. The astrophotographer waited months for the sky to appear just right -- and then took the 14 exposures that compose the above image in a single night.

the Great Comet of 2007

Explanation: Comet McNaught, the Great Comet of 2007, grew a spectacularly long and filamentary tail. The magnificent tail spread across the sky and was visible for several days to Southern Hemisphere observers just after sunset. The amazing tail showed its greatest extent on long-duration, wide-angle camera exposures. During some times, just the tail itself estimated to attain a peak brightness of magnitude -5 (minus five), was caught by the comet's discoverer in the above image just after sunset in January 2007 from Siding Spring Observatory in Australia. Comet McNaught, the brightest comet in decades, then faded as it moved further into southern skies and away from the Sun and Earth. Within the next two weeks of 2013, rapidly brightening Comet ISON might sprout a tail that rivals even Comet McNaught

Aurora and unusual Clouds Over Iceland

Explanation: What's happening in the sky? On this cold winter night in Iceland, quite a lot. First, in the foreground, lies the largest glacier in Iceland: Vatnajokull. On the far left, bright green auroras appear to emanate from the glacier as if it was a volcano. Aurora light is reflected by the foreground lake Jökulsárlón. On the far right is a long and unusual lenticular cloud tinged with green light emitted from another aurora well behind it. Just above this lenticular cloud are unusual iridescent lenticular clouds displaying a broad spectral range of colors. Far beyond the lenticular is the setting Moon, while far beyond even the Moon are setting stars.

 The above image was captured in late March of 2012.

The Flash Spectrum of the Sun

Explanation: In a flash, the visible spectrum of the Sun changed from absorption to emission on November 3rd, during the brief total phase of a solar eclipse. That fleeting moment is captured by telephoto lens and diffraction grating in this well-timed image from clearing skies over Gabon in equatorial Africa. With overwhelming light from the Sun's disk blocked by the Moon, the normally dominant absorption spectrum of the solar photosphere is hidden. What remains, spread by the diffraction grating into the spectrum of colors to the right of the eclipsed Sun, are individual eclipse images at each wavelength of light emitted by atoms along the thin arc of the solar chromosphere. The brightest images, or strongest chromospheric emission lines, are due to Hydrogen atoms that produce the red hydrogen alpha emission at the far right and blue hydrogen beta emission to the left. In between, the bright yellow emission image is caused by atoms of Helium, an element only first discovered in the flash spectrum of the Sun.

The Jets of NGC1097

Explanation: Enigmatic spiral galaxy NGC 1097 shines in southern skies, about 45 million light-years away in the chemical constellation Fornax. Its blue spiral arms are mottled with pinkish star forming regions in this colorful galaxy portrait. They seem to have wrapped around a small companion galaxy below and left of center, about 40,000 light-years from the spiral's luminous core. That's not NGC 1097's most peculiar feature, though. The very deep exposure hints of faint, mysterious jets, most easily seen to extend well beyond the bluish arms toward the lower right. In fact, four faint jets are ultimately recognized in optical images of NGC 1097. The jets trace an X centered on the galaxy's nucleus, but probably don't originate there. Instead, they could be fossil star streams, trails left over from the capture and disruption of a much smaller galaxy in the large spiral's ancient past. A Seyfert galaxy, NGC 1097's nucleus also harbors a supermassive black hole.

Plasma erupts from the sun in the shape of a massive handle

The sun is a star, a hot ball of glowing gases at the heart of our solar system. Its influence extends far beyond the orbits of distant Neptune and Pluto. Without the sun's intense energy and heat, there would be no life on Earth. And though it is special to us, there are billions of stars like our sun scattered across the Milky Way galaxy.

A solar system refers to a star and all the objects that travel in orbit around it. Our solar system consists of the sun - our star - eight planets and their natural satellites (such as our moon); dwarf planets; asteroids and comets. Our solar system is located in an outward spiral of the Milky Way galaxy.

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Fires and Farms in Indonesia

In late June 2013, smoke billowed from thousands of fires on the Indonesian island of Sumatra and blew across the Strait of Malacca to Malaysia and Singapore. Haze-darkened skies have become all too normal during the tropical dry season in this region; but this year, air quality degraded more than ever before in Singapore. On June 21, the nation’s air quality index reached a record 400. The maximum level for good health is 100.

A close look at Riau—the Sumatran province closest to Singapore and site of most of the fires—reveals the cause of the fires: land use. The Operational Land Imager on the Landsat 8 satellite acquired the top image on June 25, 2013, at the height of the burning episode. The image was made with a combination of visible (green) and infrared light so that fires and freshly burned land would stand out. The blue smudge across the scene is smoke, while higher clouds are white. Fires glow orange, and newly burned land is dark red. Bare soil or older burn scars are a lighter shade of red. The fires burn within well-defined, rectangular fields, showing that they were deliberately set to clear the land for farming.

The lower image, taken by Landsat 8 on May 24, 2013, shows the same area before the burning started. The grids and lines indicate that the area is almost entirely devoted to agriculture. According to land-use maps from the Indonesian government, the dark green fields are mature forest, likely palm oil and timber plantations. Paler green areas are either less-mature trees or other crops, and red fields are bare soil or burned land. The contrast between the two images shows that both mature forest and other types of land cover burned in June.

The trend of burning for agriculture holds true throughout Sumatra. Between June 1 and June 25, the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on NASA’s Aqua and Terra satellites counted thousands of fires in Sumatra. Fifty-two percent of the fires burned in areas zoned for palm oil or pulpwood plantations. Two-thirds of the fires burned on fertile peat land, where the dense, organic soil burns for days to weeks and generates more smoke, haze, pollutants, and greenhouse gases than other types of fire. Unusual wind patterns pushed the smoke toward Singapore and Malaysia, creating an air quality disaster.

In an effort to curb such burning, the Indonesian government declared a temporary moratorium on new permits for land development in primary forest and peat land between 2011 and 2013. The moratorium has had little impact, according to the U.S. Department of Agriculture’s Foreign Agricultural Service. Palm oil plantations alone have increased by an average 630,000 hectares per year between 2011 and 2013, up from a growth rate of 500,000 hectares per year in the previous decade. This growth can continue for up to a decade at this rate without breaching the moratorium because palm oil producers already hold six to seven million hectares of undeveloped land.

Palm oil production is highly profitable, and the commodity is an important export for Indonesia, the world’s largest producer. (Crop analysts forecast a record palm oil harvest of 31 million tons this year.) When converting forest to a palm oil plantation, growers harvest the timber, and then burn the remaining brush and trees before planting new seedlings. This means that as palm oil production expands, the annual fires and associated air quality issues are likely to continue.

    References

    Borneo Post (2013, June 21) Singapore haze PSI reads record high of 400 as of 11 am. Accessed July 22, 2013.

    Center for International Forestry Research (2013, July 2) Forests News: New data on Riau fires generate important insights. Accessed July 22, 2013.

    Foreign Agricultural Service, U.S. Department of Agriculture (2013, June 26) Indonesia: Palm oil expansion unaffected by forest moratorium. Accessed July 22, 2013.

    World Resources Institute Insights (2013, July 2) How Singapore can help clear the air on haze. Accessed July 22, 2013.

    World Resources Institute Insights (2013, July 17) Indonesia haze risk will remain high unless ministers keep promises. Accessed July 22, 2013.

    World Resources Institute Insights (2013, June 25) New data shows Indonesian forest fires a longstanding crisis. Accessed July 22, 2013.

    World Resources Institute Insights (2013, June 24) WRI releases updated data on the fires in Indonesia. Accessed July 22, 2013.

NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey. Caption by Holli Riebeek.

Views of a Distant Earth

July 24, 2013

On July 19, 2013, NASA spacecraft got not one but two rare and unique views of Earth from opposite ends of the solar system. While exploring Saturn, NASA’s Cassini spacecraft took the top image of Earth from a distance of about 1.45 billion kilometers (898 million miles) away. NASA’s MESSENGER spacecraft was 98 million kilometers (61 million miles) from Earth, in orbit around Mercury, when it acquired the lower image.

The Cassini view is the third-ever image of Earth from the outer solar system. Views of Earth from distant planets are rare because our planet is so close to the Sun. Sunlight would damage the spacecraft's sensitive imagers, so they are rarely pointed homeward. On July 19, however, Cassini was positioned so that Saturn blocked the Sun’s light while Earth was within the spacecraft’s field of view. Sunlight glimmers around the giant planet’s limb and lights its icy, dusty rings. The sunlit Earth is light blue. The Moon is a faint white dot to the side, but is more clearly visible in the narrow-angle camera view.

Cassini was launched in 1997 to study Saturn and its moons and rings. The July 19 image that includes Earth was part of a wider mosaic of the Saturn system as it was backlit by the Sun. This view will allow scientists to see particles and patterns in Saturn’s rings that are not often visible. The mosaic will take weeks to compile.

On the other side of the solar system, MESSENGER (Mercury Surface, Space, Environment, Geochemistry, and Ranging) was looking for potentially dim, small moons around Mercury when it acquired the lower, black and white image. The sensor required a long exposure time to capture these dim objects, which means Earth and Moon are overexposed. They appear exceptionally bright and large when, in reality, both are less than a pixel in size in this image.

“Cassini’s picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth,” said Cassini project scientist Linda Spilker. That observation holds true for the view from Mercury, as well.

References

EarthSky (2013, July 23) Earth seen from Saturn July 19, 2013. Accessed July 23, 2013.

NASA (2013, July 18) NASA interplanetary probes to take pictures of Earth from space. Accessed July 23, 2013.

NASA Jet Propulsion Laboratory (2013, July 22) NASA releases images of Earth taken by distant spacecraft. Accessed July 23, 2013.

Johns Hopkins Applied Physics Laboratory (2013, July 22) Looking back at us. Accessed July 23, 2013.

Cassini image courtesy NASA/JPL-Caltech/Space Science Institute. MESSENGER image courtesy NASA

One Special Day in the Life of Planet Earth

Earth is an ocean planet. Our home world's abundance of water -- and life -- makes it unique in our solar system. Other planets, plus a few moons, have ice, atmospheres, seasons and even weather, but only on Earth does the whole complicated mix come together in a way that encourages life -- and lots of it

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An artist's impression of our solar system with separate representations of scale and size

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A true-color image of Jupiter taken by the Cassini spacecraft. The Galilean moon Europa casts a shadow on the planet's cloud tops

Jupiter, the most massive planet in our solar system -- with dozens of moons and an enormous magnetic field -- forms a kind of miniature solar system. Jupiter does resemble a star in composition, but it did not grow big enough to ignite. The planet's swirling cloud stripes are punctuated by massive storms such as the Great Red Spot, which has raged for hundreds of years.

Jupiter's appearance is a tapestry of beautiful colors and atmospheric features. Most visible clouds are composed of ammonia. Water vapor exists deep below and can sometimes be seen through clear spots in the clouds. The planet's "stripes" are dark belts and light zones created by strong east-west winds in Jupiter's upper atmosphere.

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A Solar System can be defined as a star and all the objects orbiting it as well as all the material in that system. Our solar system includes the Sun together with the eight planets and their moons as well as all other celestial bodies that orbit the Sun.

From our small world we have gazed upon the cosmic ocean for thousands of years. Ancient astronomers observed points of light that appeared to move among the stars.

           

           

This image of Comet C/2001 Q4 (NEAT) was taken at Kitt Peak National Observatory near Tucson, Ariz. in 2004

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                        Comets are cosmic snowballs of frozen gases, rock and dust roughly the size of a small town. When a comet's orbit brings it close to the sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the sun for millions of kilometers.

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NASA's Opportunity rover found this meteorite on Mars. It is about the size of a basketball

. Little chunks of rock and debris in space are called meteoroids. They become meteors -- or shooting stars -- when they fall through a planet's atmosphere; leaving a bright trail as they are heated to incandescence by the friction of the atmosphere. Pieces that survive the journey and hit the ground are called meteorites

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Uranus' moon Ariel (white dot) and its shadow (black dot) were caught crossing the face of Uranus in this Hubble Space Telescope image.

Uranus is the only giant planet whose equator is nearly at right angles to its orbit. A collision with an Earth-sized object may explain Uranus' unique tilt. Nearly a twin in size to Neptune, Uranus has more methane in its mainly hydrogen and helium atmosphere than Jupiter or Saturn. Methane gives Uranus its blue tint.

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Eyes on the Solar System:

                       

They called these objects planets, meaning wanderers, and named them after Roman deities -- Jupiter, king of the gods; Mars, the god of war; Mercury, messenger of the gods; Venus, the goddess of love and beauty; and Saturn, father of Jupiter and god of agriculture.

The stargazers also observed comets with sparkling tails, and meteors -- or shooting stars apparently falling from the sky.

Since the invention of the telescope, three more planets have been discovered in our solar system: Uranus (1781), Neptune (1846) and Pluto (1930). Pluto was reclassified as a dwarf planet in 2006. In addition, our solar system is populated by thousands of small bodies such as asteroids and comets. Most of the asteroids orbit in a region between the orbits of Mars and Jupiter, while the home of comets lies far beyond the orbit of the dwarf planet Pluto, in the Oort Cloud.

The four planets closest to the sun -- Mercury, Venus, Earth, and Mars -- are called the terrestrial planets because they have solid rocky surfaces. The four large planets beyond the orbit of Mars -- Jupiter, Saturn, Uranus, and Neptune -- are called the gas giants.

Beyond Neptune, on the edge of the Kuiper Belt, tiny, distant, dwarf planet Pluto has a solid but icier surface than the terrestrial planets.

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Water-ice clouds, polar ice, polar regions, and geological features can be seen in this full-disk image of Mars

Mars is a cold desert world. It is half the diameter of Earth and has the same amount of dry land. Like Earth, Mars has seasons, polar ice caps, volcanoes, canyons and weather, but its atmosphere is too thin for liquid water to exist for long on the surface. There are signs of ancient floods on Mars, but evidence for water now exists mainly in icy soil and thin clouds.

Sun-scorched Mercury is only slightly larger than Earth's Moon. Like the Moon, Mercury has very little atmosphere to stop impacts, and it is covered with craters. Mercury's dayside is super-heated by the sun, but at night temperatures drop hundreds of degrees below freezing. Ice may even exist in craters. Mercury's egg-shaped orbit takes it around the sun every 88 days.

Magellan spacecraft radar data enabled scientists to penetrate Venus' thick clouds and create simulated views of the surface

Venus is a dim world of intense heat and volcanic activity. Similar in structure and size to Earth, Venus' thick, toxic atmosphere traps heat in a runaway "greenhouse effect." The scorched world has temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and deformed mountains. Venus spins slowly in the opposite direction of most planets.

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Voyager 2 captured this image of Neptune in 1989.

Dark, cold and whipped by supersonic winds, Neptune is the last of the hydrogen and helium gas giants in our solar system. More than 30 times as far from the sun as Earth, the planet takes almost 165 Earth years to orbit our sun. In 2011 Neptune completed its first orbit since its discovery in 1846.

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A Hubble Space Telescope image of Pluto and its moons. Charon is the largest moon close to Pluto. The other four bright dots are smaller moons discovered in 2005, 2011 and 2012.

Discovered in 1930, Pluto was long considered our solar system's ninth planet. But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet. This new class of worlds may offer some of the best evidence about the origins of our solar system. Pluto is also a member of a group of objects that orbit in a disc-like zone beyond the orbit of Neptune called the Kuiper Belt. This distant realm is populated with thousands of miniature icy worlds, which formed early in the history of our solar system. These icy, rocky bodies are called Kuiper Belt objects or transneptunian objects.

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The Galileo spacecraft sent back this image of the Moon as it headed into the outer solar system. The distinct bright ray crater at the bottom of the image is the Tycho impact bas

Our Moon makes Earth a more livable planet by moderating our home planet's wobble on its axis, leading to a relatively stable climate, and creating a rhythm that has guided humans for thousands of years. The Moon was likely formed after a Mars-sized body collided with Earth and the debris formed into the most prominent feature in our night sky.

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The moon's sometimes larger look when it is close to the horizon is an optical illusion.