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Have you ever seen the Milky Way's glow create shadows? To do so, conditions need to be just right. First and foremost, the sky must be relatively clear of clouds so that the long band of the Milky Way's central disk can be seen. The surroundings must be very near to completely dark, with no bright artificial lights visible anywhere. Next, the Moon cannot be anywhere above the horizon, or its glow will dominate the landscape. Last, the shadows can best be caught on long camera exposures. In this picture taken in Port Campbell National Park, Victoria, Australia, seven 15-second images of the ground and de-rotated sky were digitally added to bring up the needed light and detail. In the foreground lies Loch Ard Gorge, named after a ship that tragically ran aground in 1878. The two rocks pictured are the remnants of a collapsed arch and are named Tom and Eva after the only two people who survived that Loch Ard ship wreck. A close inspection of the water just before the rocks will s...

Yosemite National Park, California, USA December 2012 Image Credit & Copyright: Wally Pacholka

How did this big rock end up on this strange terrain? One of the more unusual places here on Earth occurs inside Death Valley, California, USA. There a dried lakebed named Racetrack Playa exists that is almost perfectly flat, with the odd exception of some very large stones. Now the flatness and texture of large playa like Racetrack are fascinating but not scientifically puzzling - they are caused by mud flowing, drying, and cracking after a heavy rain. Only recently, however, has a viable scientific hypothesis been given to explain how 300-kilogram sailing stones ended up near the middle of such a large flat surface. Unfortunately, as frequently happens in science, a seemingly surreal problem ends up having a relatively mundane solution. It turns out that high winds after a rain can push even heavy rocks across a temporarily slick lakebed. Image Credit: Nathan Alexander Explanation from: http://apod.nasa.gov/apod/ap120222.html

Have you ever watched a lightning storm in awe? Join the crowd. Oddly, nobody knows exactly how lightning is produced. What is known is that charges slowly separate in some clouds causing rapid electrical discharges (lightning), but how electrical charges get separated in clouds remains a topic of much research. Lightning usually takes a jagged course, rapidly heating a thin column of air to about three times the surface temperature of the Sun. The resulting shock wave starts supersonically and decays into the loud sound known as thunder. Lightning bolts are common in clouds during rainstorms, and on average 6,000 lightning bolts occur between clouds and the Earth every minute. This, an active lightning storm was recorded over Athens, Greece earlier July 2010. Image Credit & Copyright: Chris Kotsiopoulos Explanation from: http://apod.nasa.gov/apod/ap100720.html

If you look closely at the Moon, you will see a large airplane in front of it. Well, not always. OK, hardly ever. But if you wait for days with your camera attached to a Moon tracker in a place where airplanesare known to pass, you might catch a good photograph of it. Well, if you're lucky. OK, extremely lucky. This image was taken in September 2010 over South East Queensland, Australia using an exposure time of 1/250th of a second and, in the words of the photographer, "a nerve of steel". Image Credit & Copyright: Chris Thomas Explanation from: http://apod.nasa.gov/apod/ap100929.html

It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth - and death - is taking place. Hubble's view of the nebula shows star birth in a new level of detail. The fantasy-like landscape of the nebula is sculpted by the action of outflowing winds and scorching ultraviolet radiation from the monster stars that inhabit this inferno. In the process, these stars are shredding the surrounding material that is the last vestige of the giant cloud from which the stars were born. The immense nebula contains at least a dozen brilliant stars that are roughly estimated to be at least 50 to 100 times the mass of our Sun. The most unique and opulent inhabitant is the star Eta Carinae, at far left. Eta Carinae is in the final stages of its brief and eruptive lifespan, as evidenced by two billowing lobes of gas and dust that presage its upcoming explosion as a titanic supernova. The fireworks in the Carina region started three million years ago when...

A volcano on Krakatoa is still erupting. Perhaps most famous for the powerfully explosive eruption in 1883 that killed tens of thousands of people, ash from a violent eruption might also have temporarily altered Earth's climate as long as 1500 years ago. In 1927, eruptions caused smaller Anak Krakatau to rise from the sea, and the emerging volcanic island continues to grow at an average rate of 2 cm per day. The latest eruption of Anak Krakatau started in 2008 April and continues today. In this picture, Anak Krakatau is seen erupting from Rakata, the main island of the Krakatoai group. High above, stars including the Big Dipper are clearly apparent. Image Credit & Copyright: Marco Fulle Explanation from: http://apod.nasa.gov/apod/ap090713.html

The composite picture is a seamless blend of ultra-sharp NASA Hubble Space Telescope (HST) images combined with the wide view of the Mosaic Camera on the National Science Foundation's 0.9-meter telescope at Kitt Peak National Observatory, part of the National Optical Astronomy Observatory, near Tucson, Ariz. Astronomers at the Space Telescope Science Institute assembled these images into a mosaic. The mosaic was then blended with a wider photograph taken by the Mosaic Camera. The image shows a fine web of filamentary "bicycle-spoke" features embedded in the colorful red and blue gas ring, which is one of the nearest planetary nebulae to Earth. Because the nebula is nearby, it appears as nearly one-half the diameter of the full Moon. This required HST astronomers to take several exposures with the Advanced Camera for Surveys to capture most of the Helix. HST views were then blended with a wider photo taken by the Mosaic Camera. The portrait offers a dizzying look down what...

A dark Sun hung over Queensland, Australia on 14 November, 2012, during a much anticipated total solar eclipse. Storm clouds threatened to spoil the view along the northern coast, but minutes before totality the clouds parted. Streaming past the Moon's edge, the last direct rays of sunlight produced a gorgeous diamond ring effect in this scene from Ellis Beach between Cairns and Port Douglas. Winking out in a moment, the diamond didn't last forever though. The area was plunged into darkness for nearly 2 minutes as the Moon's shadow swept off shore toward Australia's Great Barrier Reef and out into the southern Pacific. Ranging from 1/4000 to 1/15 seconds long, five separate exposures were blended in the image to create a presentation similar to the breathtaking visual experience of the eclipse. Image Credit & Copyright: Alex Cherney Explanation from: http://apod.nasa.gov/apod/ap121117.html

While the Moon was busy passing between the Sun and Earth on January 4 for the first eclipse of 2011, the International Space Station (ISS) made its own pass between them. Powered by the Sun, orbiting the Earth, a satellite like the Moon—the ISS is an expression of how humanity is connected to and keeping an eye on all three bodies. This photo was taken by astrophotographer Thierry Legault, who set up near Muscat, Oman, to capture this view at 1:09 p.m. local time (9:09 UTC) on January 4, 2011. He had to shoot quickly, as the transit of the space station through the field of view lasted just 0.86 seconds. The ISS was moving at 7.8 kilometers per second (17,000 mph). The disk of the Sun is partly obscured on the lower left, as the Moon is 20 minutes past the maximum eclipse. The edges of the image are black because the light filters are strong, like a welder's mask, to prevent sunlight from damaging the camera. The partial solar eclipse was the first of four in 2011, with others com...

This craggy fantasy mountaintop enshrouded by wispy clouds looks like a bizarre landscape from Tolkien's "The Lord of the Rings" or a Dr. Seuss book, depending on your imagination. The NASA Hubble Space Telescope photograph, which is stranger than fiction, captures the chaotic activity atop a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby bright stars. The pillar is also being assaulted from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks. This turbulent cosmic pinnacle lies within a tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation Carina. Scorching radiation and fast winds (streams of charged particles) from hot newborn stars in the nebula are shaping and compressing the pillar, causing new stars to form within it. Streamers of hot ionized gas can be seen flowing off the ridges of the stru...

What is in the Milky Way Galaxy? • 300–500 billion stars (like the Sun, Sirius or Betelgeuse) • at least 100 billion planets (like Mars, Jupiter or Kepler-14b) • more than 10 billion planets in the Habitable Zone (like Earth, Gliese 667 Cc or Kepler-22b) And the Milky Way Galaxy is one of at least 200-500 billion galaxies in the Observable Universe (like Andromeda Galaxy, Pinwheel Galaxy or Whirlpool Galaxy) Image Credit: S. Brunier/ESO

Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards the constellation of the Unicorn (Monoceros). Image Credit & Copyright: Brian Lula Explanation from: http://apod.nasa.gov/apod/ap110214.html

How much of Jupiter's moon Europa is made of water? A lot, actually. Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa posses a deep, global ocean of liquid water beneath a layer of surface ice. The subsurface ocean plus ice layer could range from 80 to 170 kilometers in average depth. Adopting an estimate of 100 kilometers depth, if all the water on Europa were gathered into a ball it would have a radius of 877 kilometers. To scale, this intriguing illustration compares that hypothetical ball of all the water on Europa to the size of Europa itself (left) - and similarly to all the water on planet Earth.  With a volume 2-3 times the volume of water in Earth's oceans, the global ocean on Europa holds out a tantalizing destination in the search for extraterrestrial life in our Solar System Image Credit & Copyright: Kevin Hand, Jack Cook and Howard Perlman Explanation from: http://apod.nasa.gov/apod/ap120524.html

This view of Earth’s horizon as the sunsets over the Pacific Ocean was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). Anvil tops of thunderclouds are also visible. ISS, Orbit of the Earth 21 July, 2003 Image Credit: NASA

  A white shelf cloud caps brownish dirt from a dust storm, or haboob, as it travels across the Indian Ocean near Onslow on the Western Australia coast Onslow, Western Australia, Australia January 9, 2013 Images Credit: Brett Martin

Earth → Solar System → Solar Interstellar Neightborhood → Milky Way Galaxy → Local Galactic Group → Virgo Supercluster → Observable Universe → Universe → Unknown (our Universe might be a part of Multiverse) Earth - 12,700 km in diameter - Our planet Geospace - 63,000 km Sunward side; - 6,300,000 km trailing side - The space dominated by Earth's magnetic field Orbit of the Moon - 770,000 km across - The average diameter of the orbit of the Moon relative to the Earth Earth's Orbit - 300 million km across (2 AU) - The average diameter of the orbit of the Earth relative to the Sun. Contains the Sun, Mercury and Venus Inner Solar System - 6 AU across - Contains the Sun, the inner planets (Mercury, Venus, Earth and Mars) and the asteroid belt Outer Solar System - 60 AU across - Surrounds the inner Solar System; comprises the outer planets (Jupiter, Saturn, Uranus and Neptune) Kuiper Belt - 96 AU across - Belt of icy objects surrounding the outer solar system. Contains the dwarf plane...

What's that dark spot on planet Earth? It's the shadow of the Moon. This image of Earth was taken in May 2012 by MTSAT during an annular eclipse of the Sun. The dark spot appears quite unusual as clouds are white and the oceans are blue in this color corrected image. Earthlings residing within the dark spot would see part of the Sun blocked by the Moon and so receive less sunlight than normal. The spot moved across the Earth at nearly 2,000 kilometers per hour, giving many viewers less than two hours to see a partially eclipsed Sun. MTSAT circles the Earth in a geostationary orbit and so took this image from about three Earth-diameters away. Image Credit: PHL @ UPR Arecibo, NASA, EUMETSAT, NERC Satellite Receiving Station, U. Dundee Explanation from: http://apod.nasa.gov/apod/ap120530.html

This striking composite image follows the Sun's path through the December solstice day of 2005 in a beautiful blue sky, looking down the Tyrrhenian Sea coast from Santa Severa toward Fiumicino, Italy. The view covers about 115 degrees in 43 separate, well-planned exposures from sunrise to sunset. Explanation from: http://apod.nasa.gov/apod/ap101221.html Image Credit & Copyright: Danilo Pivato

Terraforming of Mars is a process by which Mars's climate and surface would be deliberately changed to make large areas of the environment hospitable to humans, thus making the colonization of Mars safer and sustainable (see Planetary engineering). There are a few proposed terraforming concepts, some of which present prohibitive economic and natural resource costs, and others that may be achievable with foreseeable technology. Motivation and ethics Future population growth, demand for resources, and an alternate solution to the Doomsday argument may require human colonization of bodies other than Earth, such as Mars, the Moon, and other objects. Space colonization will facilitate harvesting the Solar System's energy and material resources. In many respects, Mars is the most Earth-like of all the other planets in the Solar System. It is thought that Mars had a more Earth-like environment early in its history, with a thicker atmosphere and abundant water that was lost over the co...