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Explanation: Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as dusty as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars from even the depths of a light-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident. The featured exposure took over 12 hours and covers a sky area several times the size of the full moon. Also known as the Seven Sisters and M45, the...

Most models of Ceres depict a rocky crust, mantle of ice and a rocky inner core. This makes us wonder if the bright material unearthed might be ice. If so, it would gradually vaporize on the virtually air-free dwarf planet. Dawn will spend through early 2016 at Ceres during its primary mission and then remain in orbit there perpetually. We should be able to cipher the composition of the white material during that time with the spacecraft’s Gamma Ray and Neutron Detector and Visible and Infrared Mapping Spectrometer, but a lengthy stay might allow us to see changes in the...

June 19: ... 3 1/2-day old crescent moon hovering well below the planets Venus and Jupiter in the west-northwest sky. June 20: Take note on how the moon has shifted its position since last evening relative to Venus and Jupiter. The trio now resembles a broad obtuse triangle; the obtuse angle is at Jupiter. The moon appears to Jupiter’s lower left while Venus is 7 degrees to Jupiter’s lower right. ... June 24: After passing through inferior conjunction on May 30, Mercury reaches its greatest elongation from the sun in the dawn sky. This is not a very high apparition...

Explanation: Welcome to the vicennial year of the Astronomy Picture of the Day! Perhaps a source of web consistency for some, APOD is still here. As during each of the 20 years of selecting images, writing text, and editing the APOD web pages, the occasionally industrious Robert Nemiroff (left) and frequently persistent Jerry Bonnell (right) are pictured above plotting to highlight yet another unsuspecting image of our cosmos. Although the featured image may appear similar to the whimsical Vermeer composite that ran on APOD's fifth anniversary, a perceptive eye might catch that it has been digitally re-pixelated using many of...

The comet lander "spoke" for 85 seconds via its orbiter, "Rosetta" The comet lander that went into hibernation last last year has made contact with its team back on Earth, European space officials said on Sunday. In a brief and excited statement, the European Space Agency said the unmanned Philae, which landed on 67P/Churyumov-Gerasimenko in November to become the first spacecraft to touch down on a comet, sent a number of signals via its orbiter (“Rosetta”) to an operations center in Darmstadt, Germany. They were received on June 13 at 10:28 p.m., local time. Dr. Stephan Ulamec, Philae Project Manager...

Merely one of 62 confirmed or provisional moons orbiting Saturn, Tethys is easily the one with the most compelling life story. For one thing, it is a good sister to the other moons in the Saturnian brood. At 660 mi. (1,062 km) across, it’s the fifth largest of all of Saturn’s satellites and orbits at an altitude of 182,689 miles (294,009 km). But it does not fly alone. Its tiny siblings Telesto and Calypso—19 mi. and 16 mi. across (31 km and 26 km) respectively—fly with it, with Telesto in front Calypso in the rear, and Tethys herding them along...

Explanation: What are those colorful rings around the Moon? A corona. Rings like this will sometimes appear when the Moon is seen through thin clouds. The effect is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently. Lunar Coronae are one of the few quantum mechanical color effects that can be easily seen with the unaided eye. The featured lunar corona was captured around a Strawberry Moon on June 2 from La Plata, Argentina. Similar coronae that form...

Explanation: Why do many galaxies appear as spirals? A striking example is M101, shown above, whose relatively close distance of about 27 million light years allows it to be studied in some detail. Observational evidence indicates that a close gravitational interaction with a neighboring galaxy created waves of high mass and condensed gas which continue to orbit the galaxy center. These waves compress existing gas and cause star formation. One result is that M101, also called the Pinwheel Galaxy, has several extremely bright star-forming regions (called HII regions) spread across its spiral arms. M101 is so large that its immense...

Explanation: Shortly before Mars' June 2015 conjunction, the Curiosity Rover celebrated 1000 sols on the red planet. After its August 5, 2012 landing, Curiosity's 1000th sol or martian day on the surface corresponded to planet Earth's calendar date May 31, 2015. Because the line-of-sight to Mars is close to the Sun near the conjunction, radio communications are affected and the six-wheeled, car-sized robotic rover cautiously remains parked at this spot for now. The view looks back toward the stomping grounds for Curiosity's nearly 10.6 kilometer trek so far, with the hazy rim of Gale Crater in the distance. The mosaicked...

On his last full day in space aboard the International Space Station (ISS), NASA astronaut Terry Virts at last captured a truly iconic shot of one of the “Seven Wonders of the World” – the Great Pyramids of Giza in Egypt. Virts snapped the exquisitely sharp view of the Egyptian pyramids at Giza on June 10 looking out from the stations windows, just hours before entering the Soyuz return spaceship and closing the hatches behind him for his planned plummet back to Earth. He proudly posted the spectacular photo on his twitter social media account from space while serving as...

It seems like Mars has just about everything: auroras, water, and now... glass? In a paper published recently in Geology researchers announced that NASA's Mars Reconnaissance Orbiter (MRO) found deposits of glass in craters on the Martian surface. These are the first deposits ever found on Mars, and they could help us figure out if there was ever life on the red planet. On Mars, the glass was created when meteorites slammed into the Martian surface with enough force to melt some of the rocks, which then cooled quickly enough in the atmosphere, turning them into a type of glass...

In July, New Horizons crosses the next great frontier in our solar system. Mankind is about to visit one of the strangest places in our solar system. Out beyond Neptune, the Kuiper belt is home to hordes of cold, lumpy worlds -- some of which are large enough to have their own moons, but none of which we've seen up-close before. That's going to change this summer, when NASA's New Horizons spacecraft flies by "the king of the Kuiper belt": Pluto. It's no longer considered a planet, but Pluto is still an important member of our solar system, and one...

Visit another world without ever leaving your yard. A NASA website gives you the time of day when light on Earth is the same as you would see on Pluto.You can't fly to Pluto. You will never have the opportunity to set foot on its inhospitable surface. It took NASA's New Horizons spacecraft over nine years just to get close. Don't let this deter you from experiencing a little bit of Pluto back here on Earth. NASA has unveiled a "Pluto Time" website that helps space fans replicate the light conditions on the dwarf planet from any location in the...

It’s only a bright dot in a landscape of crenulated rocks, but the Rosetta team thinks it might be Philae, the little comet lander lost since November. The Rosetta and Philae teams have worked tirelessly to search for the lander, piecing together clues of its location after a series of unfortunate events during its planned landing on the surface of Comet 67P/Churyumov-Gerasimenko last November 12. ... Rosetta’s navigation and high-resolution cameras identified the first landing site and also took several pictures of Philae as it traveled above the comet before coming down for a final landing. Magnetic field measurements taken...

Maybe it’s too soon for a pity party, but the profound changes in the size and prominence of Jupiter’s Great Red Spot (GRS) in the past 100 years has me worried. After Saturn’s rings, Jupiter’s big bloody eye is one of astronomy’s most iconic sights. This titanic hurricane-like storm has charmed earthlings since Giovanni Cassini first spotted it in the mid-1600s. Will our grandchildren turn their telescopes to Jove only to see a pale pink oval like so many others rolling around the planet’s South Tropical Zone? ,,, An inspired image prompted this sad train of thought. UK astrophotographer Damian...

Explanation: Braided, serpentine filaments of glowing gas suggest this nebula's popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old planetary nebula some 1,500 light-years away along the southern border of the constellation Gemini. Like its mythological namesake, the nebula is associated with a dramatic transformation. The planetary nebula phase represents a final stage in the evolution of low mass stars like the sun, as they transform themselves from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the hot star powers the nebular glow....

NASA's New Horizons spacecraft is still 24 million miles and more than a month away from the dwarf planet Pluto, but the probe's pictures are already revealing a world that's more complicated than previously thought. "They show an increasingly complex surface with clear evidence of discrete equatorial bright and dark regions — some that may also have variations in brightness," the mission's principal investigator, Alan Stern of the Southwest Research Institute, said Thursday in an image advisory. "We can also see that every face of Pluto is different, and that Pluto's northern hemisphere displays substantial dark terrains." The brightest as...

Explanation: This colorful skyscape spans about three full moons (1.5 degrees) across nebula rich starfields along the plane of our Milky Way Galaxy in the royal northern constellation Cepheus. Near the edge of the region's massive molecular cloud some 2,400 light-years away, bright reddish emission region Sharpless (Sh) 155 lies at the upper left, also known as the Cave Nebula. About 10 light-years across the cosmic cave's bright rims of gas are ionized by ultraviolet light from hot young stars. Dusty blue reflection nebulae also abound on the interstellar canvas cut by dense obscuring clouds of dust. The long core...

Naturally, when you try to capture details in something bright, your background will go dark. But that might be what’s needed here – a change in exposure to reveal more detail in the spots at the expense of the landscape. Doubtless NASA will release enlarged and detailed images of these enigmatic dots later this summer..... Scientists still don’t understand the nature of the spot cluster, but reflective ice or salt remain the strongest possibilities. “The bright spots in this configuration make Ceres unique from anything we’ve seen before in the solar system,” said Chris Russell, principal investigator for the Dawn...