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Explanation: Is there anything interesting to see in the direction opposite the Sun? One night last month, there were quite a few things. First, the red-glowing orb on the lower right of the featured image is the full moon, darkened and reddened because it has entered Earth's shadow. Beyond Earth's cone of darkness are backscattering dust particles orbiting the Sun that standout with a diffuse glow called the gegenschein, visible as a faint band rising from the central horizon and passing behind the Moon. A nearly horizontal stripe of green airglow is also discernable just above the horizon, partly blocked...

The most bashful of all the naked eye planets makes its best dawn appearance of 2014 this weekend for northern hemisphere observers. And not only will Mercury be worth getting up for, but you’ll also stand a chance at nabbing that most elusive of astronomical phenomena — the zodiacal light — from a good dark sky sight. DST note: This post was written whilst we we’re visiting Arizona, a land that, we’re happy to report, does not for the most part observe the archaic practice of Daylight Saving Time. Life goes on, zombies do not arise, and trains still run...

Explanation: The city of Veszprem, Hungary was only briefly haunted by this mysterious spectre. On the morning of August 11, its monstrous form hovered in the mist above municipal buildings near the town center. A clue to its true identity is offered by the photographer, though, who reports he took the picture from the top of a twenty story building with the rising Sun directly at his back. That special geometry suggests this is an example of an atmospheric phenomenon called the Glory or sometimes "the Spectre of the Brocken". Also seen from mountain tops and airplanes when looking opposite...

Explanation: As far as the eye could see, it was a dark night at Las Campanas Observatory in the southern Atacama desert of Chile. But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds. Unlike aurorae powered by collisions with energetic charged particles and seen at high latitudes, the airglow is due to chemiluminescence, the production of light in a chemical reaction, and found around the globe. The chemical energy is provided by the Sun's extreme ultraviolet radiation. Like aurorae, the greenish hue of this...

Explanation: A cosmic grain of sand left the long and colorful trail across this all-sky view. Its grazing impact with planet Earth's atmosphere began at 71 kilometers per second. With the Milky Way stretching from horizon to horizon, the scene was captured on the night of November 17 from the astronomically popular high plateau at Champ du Feu in Alsace, France. Of course, the earthgrazer meteor belongs to this month's Leonid meteor shower, produced as our fair planet annually sweeps through dust from the tail of periodic Comet Tempel-Tuttle. The shower's radiant point in the constellation Leo is very close...

Explanation: Sweeping from the eastern to western horizon, this 360 degree panorama follows the band of zodiacal light along the solar system's ecliptic plane. Dust scattering sunlight produces the faint zodiacal glow that spans this fundamental coordinate plane of the celestial sphere, corresponding to the apparent yearly path of the Sun through the sky and the plane of Earth's orbit. The fascinating panorama is a mosaic of images taken from dusk to dawn over the course of a single night at two different locations on Mauna Kea. The lights of Hilo, Hawaii are on the eastern (left) horizon, with the...

A Hall of Mountain Glory Credit & Copyright: A. Tudorica (ISS Romania) Explanation: If you tried to enter this hall of fog, you would find it dissipates around you. The hall is actually an the mountain from which this picture was taken. Known as "the glory", the phenomenon is frequently seen from airplanes. The ring's center is not visible, but if it were, the shadow of the observer would appear. This shadow would likely change as clouds passed, creating a faux moving giant known as the Brocken Spectre. Pictured above, several concentric rings of the glory appear to create...

Zodiacal Light Over Laguna Verde Credit & Copyright: Manel Soria Explanation: An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles. The bright reflecting triangle is clearly visible on the right of the above image taken from Laguna Verde near Valparaíso, Chile in late July. The band of our Milky Way Galaxy on the left mirrors the zodiacal band. Zodiacal dust orbits the Sun predominantly in the same plane as the planets:...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2004 August 6 The Giant and the Glory Credit & Copyright: Franz Kerschbaum (Univ. Vienna) Explanation: On a flight from Vienna to Brussels, astronomer Franz Kerschbaum looked out the window and photographed this beautiful atmospheric phenomenon, the glory, shining in the direction directly opposite the Sun. Before airplanes, the glory, known to some as the heiligenschein or the Specter of the Brocken, was occasionally seen from mountaintops. There,...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 September 15 Zodiacal Light and the False Dawn Credit: Night Sky Live Project, CONCAM, NSF Explanation: An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles. The triangle is clearly visible on...

IN THE dark reaches of the solar system lurk swarms of hidden worlds. Too small and too distant to reflect sunlight, they have remained under the cover of darkness for billions of years. But now the outer solar system is giving up its secrets. And with them comes an astonishing claim: "It's quite possible that there is a halo of planets surrounding our solar system, just waiting to be found," says Eugene Chiang, an astronomer at the University of California, Berkeley. What makes Chiang's claim so surprising is the sheer number and size of these planets. Weighing more than...

Nasa discovers 'motorway' network between planets Nasa says an interplanetary superhighway discovered by one of its engineers will make space travel simpler. The solar system 'motorway' is a virtual network of winding tunnels and channels around the Sun and planets. Each planet and moon has five locations in space called Lagrange points, where one body's gravity balances another. Spacecraft can orbit at those points while burning little fuel. He came up with the superhighway by mapping out all the possible flight paths among the Lagrange points to see how fast or slow the spacecraft would travel. Experts say the superhighway...

YouTube posting: Actual backscatter video footage from TSA. Images are exactly what Transportation Security Officers see. Interesting technology. Hasn't Europe been using this technology for years now?

Explanation: Is there anything interesting to see in the direction opposite the Sun? One night last month, there were quite a few things. First, the red-glowing orb on the lower right of the featured image is the full moon, darkened and reddened because it has entered Earth's shadow. Beyond Earth's cone of darkness are backscattering dust particles orbiting the Sun that standout with a diffuse glow called the gegenschein, visible as a faint band rising from the central horizon and passing behind the Moon. A nearly horizontal stripe of green airglow is also discernable just above the horizon, partly blocked...

Explanation: Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above from last year is one of the more spectacular pictures of the gegenschein yet taken. Here a deep exposure of an extremely dark sky over Las Campanas Observatory...

Explanation: Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above from 2008 October is one of the more spectacular pictures of the gegenschein yet taken. Here a deep exposure of an extremely dark sky over Paranal Observatory in...

Explanation: Ghostly apparitions of two fundamental planes in planet Earth's sky span this October all-sky view. The scene was captured from a lakeside campsite under dark skies in northern Maine, USA. In it, the plane of our Milky Way Galaxy arcs above faint airglow along the horizon. Zodiacal light, a band of dust scattering sunlight along the solar system's ecliptic plane, stretches almost horizontally across the wide field and intersects the Milky way near a point marked by bright planet Jupiter. Right of Jupiter, past the Pleiades star cluster, is the brightening of the Zodiacal band known as the Gegenschein,...