2017 July 6

**panosol** Πεμ Ιουλ 06, 2017 8:38 pm

2017 July 6
Astronomy Picture of the Day - Σελίδα 9 PIA21449_Atlas_Daphnis_Pan

Atlas, Daphnis, and Pan
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Atlas, Daphnis, and Pan are small, inner, ring moons of Saturn, shown at the same scale in this montage of images from the still Saturn-orbiting Cassini spacecraft. In fact, Daphnis was discovered in Cassini images from 2005. Atlas and Pan were first sighted in images from the Voyager 1 and 2 spacecraft. Flying saucer-shaped Atlas orbits near the outer edge of Saturn's bright A Ring while Daphnis orbits inside the A Ring's narrow Keeler Gap and Pan within the A Ring's larger Encke Gap. The curious equatorial ridges of the small ring moons could be built up by the accumulation of ring material over time. Even diminutive Daphnis makes waves in the ring material as it glides along the edge of the Keeler Gap.

**panosol** Παρ Ιουλ 07, 2017 9:16 pm

2017 July 7
Astronomy Picture of the Day - Σελίδα 9 Messier106_NGC4217_Feltoti

A View Toward M106
Image Credit & Copyright: Peter Feltoti

Explanation: Big, bright, beautiful spiral, Messier 106 dominates this cosmic vista. The two degree wide telescopic field of view looks toward the well-trained constellation Canes Venatici, near the handle of the Big Dipper. Also known as NGC 4258, M106 is about 80,000 light-years across and 23.5 million light-years away, the largest member of the Canes II galaxy group. For a far away galaxy, the distance to M106 is well-known in part because it can be directly measured by tracking this galaxy's remarkable maser, or microwave laser emission. Very rare but naturally occuring, the maser emission is produced by water molecules in molecular clouds orbiting its active galactic nucleus. Another prominent spiral galaxy on the scene, viewed nearly edge-on, is NGC 4217 below and right of M106. The distance to NGC 4217 is much less well-known, estimated to be about 60 million light-years.

**panosol** Σαβ Ιουλ 08, 2017 7:27 pm

2017 July 8
Astronomy Picture of the Day - Σελίδα 9 Ic342_rector2048

Hidden Galaxy IC 342
Credit & Copyright: T. Rector (U. Alaska Anchorage), H. Schweiker, WIYN, NOAO, AURA, NSF

Explanation: Similar in size to large, bright spiral galaxies in our neighborhood, IC 342 is a mere 10 million light-years distant in the long-necked, northern constellation Camelopardalis. A sprawling island universe, IC 342 would otherwise be a prominent galaxy in our night sky, but it is hidden from clear view and only glimpsed through the veil of stars, gas and dust clouds along the plane of our own Milky Way galaxy. Even though IC 342's light is dimmed by intervening cosmic clouds, this sharp telescopic image traces the galaxy's own obscuring dust, blue star clusters, and glowing pink star forming regions along spiral arms that wind far from the galaxy's core. IC 342 may have undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way.

**panosol** Κυρ Ιουλ 09, 2017 7:44 pm

2017 July 9
Astronomy Picture of the Day - Σελίδα 9 Earth_At_Night_Suomi_NPP_3600

Earth at Night
Image Credit : NASA, NOAA NGDC, Suomi-NPP, Earth Observatory,
Data and Processing: Chris Elvidge and Robert Simmon

Explanation: Can you find your favorite country or city? Surprisingly, on this world-wide nightscape, city lights make this task quite possible. Human-made lights highlight particularly developed or populated areas of the Earth's surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The featured composite was created from images that were collected during cloud-free periods in April and October 2012 by the Suomi-NPP satellite, from a polar orbit about 824 kilometers above the surface, using its Visible Infrared Imaging Radiometer Suite (VIIRS).

**panosol** Δευ Ιουλ 10, 2017 8:43 pm

2017 July 10
Astronomy Picture of the Day - Σελίδα 9 NGC1512_Schmidt_1342

Spiral Galaxy NGC 1512: The Nuclear Ring
Image Credit: NASA, ESA, Hubble, LEGUS; Acknowledgement: Judy Schmidt

Explanation: What's happening around the center of this spiral galaxy? Seen in total, NGC 1512 appears to be a barred spiral galaxy -- a type of spiral that has a straight bar of stars across its center. This bar crosses an outer ring, though, a ring not seen as it surrounds the pictured region. Featured in this Hubble Space Telescope image is an inner ring -- one that itself surrounds the nucleus of the spiral. The two rings are connected not only by a bar of bright stars but by dark lanes of dust. Inside of this inner ring, dust continues to spiral right into the very center -- possibly the location of a large black hole. The rings are bright with newly formed stars which may have been triggered by the collision of NGC 1512 with its galactic neighbor, NGC 1510.

**panosol** Τρι Ιουλ 11, 2017 8:58 pm

2017 July 11
Astronomy Picture of the Day - Σελίδα 9 Omega_Centauri_ODay_4620

Star Cluster Omega Centauri in HDR
Image Credit & Copyright: Mike O'Day

Explanation: Behold the largest ball of stars in our galaxy. Omega Centauri is packed with about 10 million stars, many older than our Sun and packed within a volume of only about 150 light-years in diameter. The star cluster is the largest and brightest of 200 or so known globular clusters that roam the halo of our Milky Way galaxy. Though most star clusters consist of stars with the same age and composition, the enigmatic Omega Cen exhibits the presence of different stellar populations with a spread of ages and chemical abundances. In fact, Omega Cen may be the remnant core of a small galaxy merging with the Milky Way. The featured image shows so many stars because it merged different exposures with high dynamic range (HDR) techniques. Omega Centauri, also known as NGC 5139, lies about 15,000 light-years away toward the southern constellation of the Centaurus.

**panosol** Τετ Ιουλ 12, 2017 8:22 pm

2017 July 12
Astronomy Picture of the Day - Σελίδα 9 M63-_HST-_Subaru-_LL

Messier 63: The Sunflower Galaxy
Image Credit & Copyright: Data - Hubble Legacy Archive, Subaru Telescope (NAOJ), Don Goldman
Processing - Robert Gendler, Roberto Colombari, Don Goldman

Explanation: A bright spiral galaxy of the northern sky, Messier 63 is about 25 million light-years distant in the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across. That's about the size of our own Milky Way Galaxy. Known by the popular moniker, The Sunflower Galaxy, M63 sports a bright yellowish core in this sharp composite image from space- and ground-based telescopes. Its sweeping blue spiral arms are streaked with cosmic dust lanes and dotted with pink star forming regions. A dominant member of a known galaxy group, M63 has faint, extended features that are likely star streams from tidally disrupted satellite galaxies. M63 shines across the electromagnetic spectrum and is thought to have undergone bursts of intense star formation.

**panosol** Πεμ Ιουλ 13, 2017 7:53 pm

2017 July 13
Astronomy Picture of the Day - Σελίδα 9 Tafreshi_NIK2197s

Full Moon and Boston Light
Image Credit & Copyright: Babak Tafreshi (TWAN)

Explanation: This well-planned telephoto timelapse captures July's Full Moon rise across outer Boston Harbor, Massachusetts, planet Earth. In the foreground, the historic terrestrial beacon is known as Boston Light. July's Full Moon is known to some as a Thunder Moon, likely a reference to the sounds of the northern summer month's typically stormy weather. But the eastern sky was clear for this video sequence. Near the horizon, the long sight-line through atmospheric layers filters and refracts the moonlight, causing the rising Moon's reddened color, ragged edges and distorted shape.

**panosol** Παρ Ιουλ 14, 2017 7:55 pm

2017 July 14
Astronomy Picture of the Day - Σελίδα 9 N4449_DPestana_RVillaverde_HLA2048

NGC 4449: Close-up of a Small Galaxy
Image Credit & Copyright: Data - Hubble Legacy Archive, ESA, NASA;
Processing - Domingo Pestana Galvan, Raul Villaverde Fraile

Explanation: (xxxedit and linkxxx) Grand spiral galaxies often seem to get all the glory. Their young, blue star clusters and pink star forming regions along sweeping spiral arms are guaranteed to attract attention. But small irregular galaxies form stars too, like NGC 4449, about 12 million light-years distant. Less than 20,000 light-years across, the small island universe is similar in size, and often compared to our Milky Way's satellite galaxy, the Large Magellanic Cloud (LMC). This remarkable Hubble Space Telescope close-up of the well-studied galaxy was reprocessed to highlight the telltale reddish glow of hydrogen gas. The glow traces NGC 4449's widespread star forming regions, some even larger than those in the LMC, with enormous interstellar arcs and bubbles blown by short-lived, massive stars. NGC 4449 is a member of a group of galaxies found in the constellation Canes Venatici. It also holds the distinction of being the first dwarf galaxy with an identified tidal star stream.

**panosol** Σαβ Ιουλ 15, 2017 8:09 pm

2017 July 15
Astronomy Picture of the Day - Σελίδα 9 Redspot_Detail_Juno_Eichstadt_Doran_crop

Close-up of The Great Red Spot
Image Credit: NASA, Juno, SwRI, MSSS, Gerald Eichstadt, Sean Doran

Explanation: On July 11, the Juno spacecraft once again swung near to Jupiter's turbulent cloud tops in its looping 53 day orbit around the Solar System's ruling gas giant. About 11 minutes after perijove 7, its closest approach on this orbit, it passed directly above Jupiter's Great Red Spot. During the much anticipated fly over, it captured this close-up image data from a distance of less than 10,000 kilometers. The raw JunoCam data was subsequently processed by citizen scientists. Very long-lived but found to be shrinking, the Solar System's largest storm system was measure to be 16,350 kilometers wide on April 15. That's about 1.3 times the diameter of planet Earth.

**panosol** Κυρ Ιουλ 16, 2017 8:45 pm

2017 July 16
Astronomy Picture of the Day - Σελίδα 9 Lightning_Eclipse_Kotsiopoulos_960

Lightning Eclipse from the Planet of the Goats
Image Credit & Copyright: Chris Kotsiopoulos (GreekSky)

Explanation: Thunderstorms almost spoiled this view of the spectacular 2011 June 15 total lunar eclipse. Instead, storm clouds parted for 10 minutes during the total eclipse phase and lightning bolts contributed to the dramatic sky. Captured with a 30-second exposure the scene also inspired one of the more memorable titles (thanks to the astrophotographer) in APOD's now 22-year history. Of course, the lightning reference clearly makes sense, and the shadow play of the dark lunar eclipse was widely viewed across planet Earth in Europe, Africa, Asia, and Australia. The picture itself, however, was shot from the Greek island of Ikaria at Pezi. That area is known as "the planet of the goats" because of the rough terrain and strange looking rocks.

**panosol** Δευ Ιουλ 17, 2017 7:34 pm

2017 July 17

Moon Shadow versus Sun Reflection
Image Credit: Himawari-8, NASA's SVS (GSFC)

Explanation: What are those lights and shadows crossing the Earth? As the featured five-second time-lapse video progresses, a full day on planet Earth is depicted as seen from Japan's Himawari-8 satellite in geostationary orbit high above the Pacific Ocean. The Sun rises to the right and sets to the left, illuminating the half of Earth that is most directly below. A reflected image of the Sun -- a Sun glint -- is visible as a bright spot that moves from right to left. More unusual, though, is the dark spot that moves from the lower left to upper right That is the shadow of the Moon, and it can only appear when the Moon goes directly between the Earth and the Sun. Last year, on the day these images were taken, the most deeply shadowed region experienced a total eclipse of the Sun. Next month a similarly dark shadow will sweep right across the USA.

**panosol** Τρι Ιουλ 18, 2017 7:21 pm

2017 July 18
Astronomy Picture of the Day - Σελίδα 9 Thunder_Moon_Pisa_Meniero_5760

Thunder Moon over Pisa
Image Credit & Copyright: Marco Meniero

Explanation: What's wrong with this picture? If you figure it out, you may then realize where the image was taken. The oddity lies actually in one of the buildings -- it leans. The Leaning Tower of Pisa has been an iconic legend since shortly after its construction began in the year 1173. Now part of a UNESCO World Heritage Site, folklore holds that Galileo used the leaning tower to dramatically demonstrate the gravitational principle that objects of different mass fall the same. Between the Leaning Tower of Pisa on the right and Pisa Cathedral and the Pisa Baptistery on the left, a full "Thunder" moon was visible last week when the image was taken. Using modern analyses, the tower has been successfully stabilized and, barring the unexpected, should hold its present tilt for the next 200 years.

**panosol** Τετ Ιουλ 19, 2017 7:18 pm

2017 July 19
Astronomy Picture of the Day - Σελίδα 9 Ireson_Hill_Curiosity_6720

Ireson Hill on Mars
Image Credit: NASA, JPL-Caltech, MSSS

Explanation: What created this unusual hill on Mars? Its history has become a topic of research, but its shape and two-tone structure makes it one of the more unusual hills that the robotic Curiosity rover on Mars has rolled near. Dubbed Ireson Hill, the mound rises about 5 meters high and spans about 15 meters across. Ireson Hill is located on the Bagnold Dune field on the slope of Mount Sharp in Gale Crater on Mars. The featured 41-image panorama has been horizontally compressed to include the entire hill. The image was taken on February 2 and released last week. Because Mars is moving behind the Sun as seen from the Earth, NASA will soon stop sending commands to its Martian orbiters and rovers until about August 1.

**panosol** Πεμ Ιουλ 20, 2017 7:17 pm

2017 July 20
Astronomy Picture of the Day - Σελίδα 9 MOSAIC_IC1396_Ha_SHO_blanco

IC 1396: Emission Nebula in Cepheus
Image Credit & Copyright: César Blanco González

Explanation: Stunning emission nebula IC 1396 mixes glowing cosmic gas and dark dust clouds in the high and far off constellation of Cepheus. Energized by the bright central star seen here, this star forming region sprawls across hundreds of light-years, spanning over three degrees on the sky while nearly 3,000 light-years from planet Earth. Among the intriguing dark shapes within IC 1396, the winding Elephant's Trunk nebula lies just below center. Stars could still be forming inside the dark shapes by gravitational collapse. But as the denser clouds are eroded away by powerful stellar winds and radiation, any forming stars will ultimately be cutoff from the reservoir of star stuff. The gorgeous color view is a composition of image data from narrowband filters, mapping emission from the nebula's atomic oxygen, hydrogen, and sulfur into blue, green, and red hues.

**panosol** Παρ Ιουλ 21, 2017 9:03 pm

2017 July 21
Astronomy Picture of the Day - Σελίδα 9 STSCI-_Mars_Phobos_Comp3000

Phobos: Moon over Mars
Image Credit: NASA, ESA, Zolt Levay (STScI) - Acknowledgment: J.Bell (ASU) and M.Wolff (SSI)

Explanation: A tiny moon with a scary name, Phobos emerges from behind the Red Planet in this timelapse sequence from the Earth-orbiting Hubble Space Telescope. Over 22 minutes the 13 separate exposures were captured near the 2016 closest approach of Mars to planet Earth. Martians have to look to the west to watch Phobos rise, though. The small moon is closer to its parent planet than any other moon in the Solar System, about 3,700 miles (6,000 kilometers) above the Martian surface. It completes one orbit in just 7 hours and 39 minutes. That's faster than a Mars rotation, which corresponds to about 24 hours and 40 minutes. So on Mars, Phobos can be seen to rise above the western horizon 3 times a day. Still, Phobos is doomed.

**panosol** Σαβ Ιουλ 22, 2017 11:07 am

2017 July 22
Astronomy Picture of the Day - Σελίδα 9 AS11-40-5872_HR

Apollo 11: Catching Some Sun
Image Credit: Apollo 11, NASA (Image scanned by Kipp Teague)

Explanation: Bright sunlight glints and long dark shadows mark this image of the lunar surface. It was taken July 20, 1969 by Apollo 11 astronaut Neil Armstrong, the first to walk on the Moon. Pictured is the mission's lunar module, the Eagle, and spacesuited lunar module pilot Buzz Aldrin unfurling a long sheet of foil also known as the Solar Wind Composition Experiment. Exposed facing the Sun, the foil trapped particles streaming outward in the solar wind, catching a sample of material from the Sun itself. Along with moon rocks and lunar soil samples, the solar wind collector was returned for analysis in earthbound laboratories.

**panosol** Κυρ Ιουλ 23, 2017 10:21 pm

2017 July 23
Astronomy Picture of the Day - Σελίδα 9 Mercuryflyby2_messenger_1024

Mercury as Revealed by MESSENGER
Image Credit: MESSENGER, NASA, JHU APL, CIW

Explanation: Mercury had never been seen like this before. In 2008, the robotic MESSENGER spacecraft buzzed past Mercury for the second time and imaged terrain mapped previously only by comparatively crude radar. The featured image was recorded as MESSENGER looked back 90 minutes after passing, from an altitude of about 27,000 kilometers. Visible in the image, among many other newly imaged features, are unusually long rays that appear to run like meridians of longitude out from a young crater near the northern limb. MESSENGER entered orbit around Mercury in 2011 and finished its primary mission in 2012, but took detailed measurements until 2015, at which time it ran out of fuel and so was instructed to impact Mercury's surface.

**panosol** Δευ Ιουλ 24, 2017 7:52 pm

2017 July 24
Astronomy Picture of the Day - Σελίδα 9 Hybrid_Solar_Eclipse_Kamenew_1584

A Hybrid Solar Eclipse over Kenya
Image Credit & Copyright: Eugen Kamenew (Kamenew Photography)

Explanation: Chasing solar eclipses can cause you to go to the most interesting places and meet the most interesting people. Almost. For example, chasing this eclipse brought this astrophotographer to Kenya in 2013. His contact, a member of the Maasai people, was to pick him up at the airport, show him part of southern Kenya, and even agreed to pose in traditional warrior garb on a hill as the hopefully spectacular eclipse set far in background. Unfortunately, this contact person died unexpectedly a week before the astrophotographer's arrival, and so he never got to participate in the shoot, nor know that the resulting image went on to win an international award for astrophotography. Pictured in 2013 from Kenya, the Moon covers much of the Sun during a hybrid eclipse, a rare type of solar eclipse that appears as total from some Earth locations, but annular in others. During the annular part of the eclipse, the Moon was too far from the Earth to block the entire Sun. Next month a total solar eclipse will cross the USA.

**panosol** Τρι Ιουλ 25, 2017 8:23 pm

2017 July 25
Astronomy Picture of the Day - Σελίδα 9 ISSdrone_jaxa_4928

Int-Ball Drone Activated on the Space Station
Image Credit: JAXA, ISS, NASA

Explanation: What if you were followed around by a cute floating ball that kept taking your picture? Then you might be an astronaut on today's International Space Station (ISS). Designed by the Japan Aerospace Exploration Agency (JAXA), the JEM Internal Ball Camera -- informally "Int-Ball" -- is a bit larger than a softball, can float and maneuver by itself but also be controlled remotely, can take high resolution images and videos, and is not related to Hello Kitty. Int-Ball was delivered to the ISS in early June and is designed to allow ground-control to increase the monitoring of ISS equipment and activities while decreasing time demands on human astronauts. Int-Ball moves by turning on small internal fans and sees with a camera located between its two dark eyes.

**panosol** Τετ Ιουλ 26, 2017 7:43 pm

2017 July 26
Astronomy Picture of the Day - Σελίδα 9 Monument_Valley_Masterson_2048

The Milky Way over Monument Valley
Image Credit & Copyright: Tom Masterson

Explanation: You don't have to be at Monument Valley to see the Milky Way arc across the sky like this -- but it helps. Only at Monument Valley USA would you see a picturesque foreground that includes these iconic rock peaks called buttes. Buttes are composed of hard rock left behind after water has eroded away the surrounding soft rock. In the featured image taken last month, the closest butte on the left and the butte to its right are known as the Mittens, while Merrick Butte can be seen farther to the right. Green airglow fans up from the horizon. High overhead stretches a band of diffuse light that is the central disk of our spiral Milky Way Galaxy. The band of the Milky Way can be spotted by almost anyone on almost any clear night when far enough from a city and surrounding bright lights, but a sensitive digital camera is needed to capture these colors in a dark night sky.

**panosol** Πεμ Ιουλ 27, 2017 6:52 pm

2017 July 27
Astronomy Picture of the Day - Σελίδα 9 TOA1-_M8_M20-_SL-_DCP01and_B600-09-_Final7-_Cc2048

A Sagittarius Triplet
Image Credit & Copyright: Josep Drudis

Explanation: These three bright nebulae are often featured on telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula above and left of center, and colorful M20 near the bottom of the frame. The third emission region includes NGC 6559, right of M8 and separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. Over a hundred light-years across the expansive M8 is also known as the Lagoon Nebula. M20's popular moniker is the Trifid. Glowing hydrogen gas creates the dominant red color of the emission nebulae. In striking contrast, blue hues in the Trifid are due to dust reflected starlight. The colorful composite skyscape was recorded with two different telescopes to capture a widefield image of the area and individual close-ups at higher resolution.

**panosol** Παρ Ιουλ 28, 2017 7:45 pm

2017 July 28
Astronomy Picture of the Day - Σελίδα 9 PIA21617_Cassini_Noodle

Noodle Mosaic of Saturn
Image Credit: NASA, JPL-Caltech, Space Science Institute, Hampton University

Explanation: On April 26 the Cassini spacecraft swooped toward Saturn on the first of its Grand Finale dives between Saturn and rings. In this long, thin, noodle mosaic, a rapid series of 137 low resolution images captured by Cassini's wide-angle camera track its progress across the gas giant's swirling cloud tops. The mosaic projection maps the arc along Saturn's atmospheric curve on to a flat image plane. At top, the first mosaic panel is centered at 90 degrees north, about 72,400 kilometers above Saturn's dark north polar vortex. As the mosaic progresses it narrows, the pixel scale shrinking from 8.7 kilometers to 1 kilometer per pixel. For the last panel, the spacecraft is 8,374 kilometers above a region 18 degrees north of Saturn's equator. Frame orientation changes near the bottom as Cassini rotates to maneuver its large, dish-shaped, high-gain antenna forward, providing a shield before crossing Saturn's ring plane.

**panosol** Σαβ Ιουλ 29, 2017 8:47 am

2017 July 29
Astronomy Picture of the Day - Σελίδα 9 Aurora_iss052e007857

Aurora Slathers up the Sky
Image Credit: Jack Fischer, Expedition 52, NASA

Explanation: Like salsa verde on your favorite burrito, a green aurora slathers up the sky in this June 25 snapshot from the International Space Station. About 400 kilometers (250 miles) above Earth, the orbiting station is itself within the upper realm of the auroral displays. Aurorae have the signature colors of excited molecules and atoms at the low densities found at extreme altitudes. Emission from atomic oxygen dominates this view. The tantalizing glow is green at lower altitudes, but rarer reddish bands extend above the space station's horizon. The orbital scene was captured while passing over a point south and east of Australia, with stars above the horizon at the right belonging to the constellation Canis Major, Orion's big dog. Sirius, alpha star of Canis Major, is the brightest star near the Earth's limb.

**panosol** Κυρ Ιουλ 30, 2017 7:45 pm

2017 July 30
Astronomy Picture of the Day - Σελίδα 9 Antarctic_Eclipse_bruenjes_650

A Total Eclipse at the End of the World
Image Credit & Copyright: Fred Bruenjes (moonglow.net)

Explanation: Would you go to the end of the world to see a total eclipse of the Sun? If you did, would you be surprised to find someone else there already? In 2003, the Sun, the Moon, Antarctica, and two photographers all lined up in Antarctica during an unusual total solar eclipse. Even given the extreme location, a group of enthusiastic eclipse chasers ventured near the bottom of the world to experience the surreal momentary disappearance of the Sun behind the Moon. One of the treasures collected was the featured picture -- a composite of four separate images digitally combined to realistically simulate how the adaptive human eye saw the eclipse. As the image was taken, both the Moon and the Sun peeked together over an Antarctic ridge. In the sudden darkness, the magnificent corona of the Sun became visible around the Moon. Quite by accident, another photographer was caught in one of the images checking his video camera. Visible to his left are an equipment bag and a collapsible chair. A more easily visible solar eclipse will occur in about three weeks and be visible from the USA.