The Lonely Neutron Star in Supernova Remnant E0102-72.3 - Astronomy picture of the day - 2018 September 30

The Lonely Neutron Star in Supernova Remnant E0102-72.3 

Credit: X-ray (NASA/CXC/ESO/F. Vogt et al.); Optical (ESO/VLT/MUSE & NASA/STScI)

Explanation: Why is this neutron star off-center? Recently a lone neutron star has been found within the debris left over from an old supernova explosion. The "lonely neutron star" in question is the blue dot at the center of the red nebula near the bottom left of E0102-72.3. In the featured image composite, blue represents X-ray light captured by NASA's Chandra Observatory, while red and green represent optical light captured by ESO's Very Large Telescopein Chile and NASA's Hubble Space Telescope in orbit. The displaced position of this neutron star is unexpected since the dense star is thought to be the core of the star that exploded in the supernova and created the outer nebula. It could be that the neutron star in E0102 was pushed away from the nebula's center by the supernova itself, but then it seems odd that the smaller red ring remains centered on the neutron star. Alternatively, the outer nebula could have been expelled during a different scenario -- perhaps even involving another star. Future observations of the nebulas and neutron star appear likely to resolve the situation.

Ces codes secrets donnent accès aux fonctions cachées du téléphone - Téléphonie

Nous avons tous notre téléphone portable à portée de main en permanence. Mais peu de gens connaissent toutes leurs options secrètes, qui peuvent être activées avec de simples combinaisons de touches. Il existe une grande variété de combinaisons, certaines s’appliquent à tous les types de téléphones, tandis que d’autres fonctionnent uniquement sur certains modèles.

Sympa-sympa.com a rassemblé en un seul article tous les codes intéressants qui vous donneront accès aux options cachées du portable.

Aerobuzz - L’A330-900 certifié en Europe - Aeronautique

Le programme A330neo a été mené en un temps réduit. Le premier vol a en effet eu lieu, il y a tout juste 11 mois. 1.400 heures de vol de certification ont été effectuées dans cet intervalle par trois avions dont l’appareil destiné à la compagnie portugaise TAP. Plusieurs options avaient déjà été évaluées en vol entre le quatrième trimestre 2015 et le deuxième trimestre 2017 sur un A330, avant même le premier vol.

L’A330-900 et l’A330-800 sont les deux variantes de l’A330neo, autrement dit du vénérable biréacteur long courrier A330 remotorisé avec des moteurs Trent 7000 de Rolls-Royce, et doté d’une voilure optimisée et de nouveaux sharklets (dispositifs d’extrémité de voilure) constitués de matériaux composites plus légers. « Ensemble, ces avancées se traduisent par une réduction significative de la consommation de carburant, de l’ordre de 25 pour cent par rapport aux avions de la même capacité des générations précédentes. », assure Airbus.

Aerobuzz

The Light, the Dark, and the Dusty - Astronomy picture of the day - 2018 September 28

The Light, the Dark, and the Dusty 
Image Credit & Copyright: Tasos Liampos

Explanation: This colorful skyscape spans about two full moons 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 is below and right of center, also known as the Cave Nebula. About 10 light-years across the cosmic cave's bright walls of gas are ionized by ultraviolet light from the hot young stars around it. Dusty blue reflection nebulae, like vdB 155 at upper left, and dense obscuring clouds of dust also abound on the interstellar canvas. Astronomical explorations have revealed other dramatic signs of star formation, including the bright red fleck of Herbig-Haro (HH) 168. Near top center in the frame, the Herbig-Haro object emission is generated by energetic jets from a newborn star.

The Sun's Spectrum with its Missing Colors - Astronomy picture of the day - 2018 September 26

The Sun's Spectrum with its Missing Colors  Image Credit: Nigel Sharp (NSF), FTS, NSO, KPNO, AURA, NSF

Explanation: It is still not known why the Sun's light is missing some colors. Here are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device. The spectrum was created at the McMath-PierceSolar Observatory and shows, first off, that although our white-appearing Sun emits light of nearly every color, it does indeed appear brightest in yellow-green light. The dark patches in the above spectrum arise from gas at or above theSun's surface absorbing sunlight emitted below. Since different types of gas absorb different colors of light, it is possible to determine what gasses compose the Sun. Helium, for example, was first discovered in 1870 on a solar spectrum and only later found here on Earth. Today, the majority of spectral absorption lines have been identified - but not all.

Highlights of the North Autumn Sky - Astronomy picture of the day - 2018 September 25

Highlights of the North Autumn Sky Illustration Credit & Copyright: Universe2go.com

Explanation: What can you see in the night sky this season? The featured graphic gives a few highlights for Earth's northern hemisphere. Viewed as a clock face centered at the bottom, early (northern) autumn sky events fan out toward the left, while late autumn events are projected toward the right. Objects relatively close to Earth are illustrated, in general, as nearer to the cartoon figure with the telescope at the bottom center -- although almost everything pictured can be seen without a telescope. As happens during any season, constellations appear the same year to year, and, as usual, the Leonids meteor shower will peak in mid-November. Also as usual, the International Space Station(ISS) can be seen, at times, as a bright spot drifting across the sky after sunset. Planets visible after sunset this autumn include Jupiter and Mars, and during late autumn, Saturn.

Rover 1A Hops on Asteroid Ryugu - Astronomy picture of the day - 2018 September 24

Rover 1A Hops on Asteroid Ryugu 
Image Credit & Copyright: ISAS, JAXA, Hayabusa2 Mission

Explanation: Two small robots have begun hopping around the surface of asteroid Ryugu. The rovers, each the size of a small frying pan, move around the low gravity of kilometer-sized 162173 Ryugu by hopping, staying aloft for about 15 minutes and typically landing again several meters away. On Saturday, Rover 1A returned an early picture of its new home world, on the left, during one of its first hops. On Friday, lander MINERVA-II-1 detached from its mothership Hayabusa2, dropped Rovers 1A and 1B, and then landed on Ryugu. Studying Ryugu could tell humanity not only about Ryugu's surface and interior, but about what materials were available in the early Solar System for thedevelopment of life. Two more hopping rovers are planned for release, and Hayabusa2 itself is scheduled to collect a surface sample from Ryugu and return it to Earth for detailed analysis before 2021.

Antonio Vivaldi - "Outono" - Video - Musica

"Outono"

Equinox: Analemma over the Callanish Stones - Astronomy picture of the day - 2018 September 23

Equinox: Analemma over the Callanish Stones 
Image Credit & Copyright: Giuseppe Petricca

Explanation: Does the Sun return to the same spot on the sky every day at the same time? No. A more visual answer to that question is an analemma, a composite image taken from the same spot at the same time over the course of a year. The featured analemma was composed from images taken every few days at 4 pm near the village of Callanish in the Outer Hebrides in Scotland, UK. In the foreground are the Callanish Stones, a stone circle built around 2700 BC during humanity's Bronze Age. It is not known if the placement of the Callanish Stones has or had astronomical significance. The ultimate causes for the figure-8 shape of this an all analemmas are the tilt of the Earth axis and theellipticity of the Earth's orbit around the Sun. At the solstices, the Sun will appear at the top or bottom of an analemma. Equinoxes, however, correspond to analemma middle points -- not the intersection point. Today at 1:54 am (UT) is the equinox ("equal night"), when day and night are equal over all of planet Earth. Many cultures celebrate a change of season at an equinox.

Window Seat over Hudson Bay - Astronomy picture of the day - 2018 September 22

Window Seat over Hudson Bay 
Image Credit & Copyright: Ralf Rohner

Explanation: On the August 18 night flight from San Francisco to Zurich, a window seat offered this tantalizing view when curtains of light draped a colorful glow across the sky over Hudson Bay. Constructed by digitally stacking six short exposures made with a hand held camera, the scene records the shimmering aurora borealis or northern lights just as the approaching high altitude sunrise illuminated the northeastern horizon. It also caught the flash of a Perseidmeteor streaking beneath the handle stars of the Big Dipper of the north. A few days past the meteor shower's peak, its trail still points across the sky toward Perseus. Beautiful aurorae and shower meteors both occur in Earth's upper atmosphere at altitudes of 100 kilometers or so, far above commercial airline fights. The aurora are caused by energetic charged particles from the magnetosphere, while meteors are trails of comet dust.

Irregular Galaxy NGC 55 - Astronomy picture of the day - 2018 September 21

Irregular Galaxy NGC 55 
Image Credit & Copyright: Martin Pugh

Explanation: Irregular galaxy NGC 55 is thought to be similar to the Large Magellanic Cloud (LMC). But while the LMC is about 180,000 light-years away and is a well known satellite of our own Milky Way Galaxy, NGC 55 is more like 6 million light-years distant and is a member of the Sculptor Galaxy Group. Classified as an irregular galaxy, in deep exposures the LMC itself resembles a barred disk galaxy. Spanning about 50,000 light-years, NGC 55 is seen nearly edge-on though, presenting a flattened, narrow profile in contrast with our face-on view of the LMC. Just as large star forming regions create emission nebulae in the LMC, NGC 55 is also seen to be producing new stars. This highly detailed galaxy portrait highlights a bright core crossed with dust clouds, telltale pinkish star forming regions, and young blue star clusters in NGC 55.

The Piano Guys - "Beethoven's Five Secrets - One Republic" Video - Music - Live

"Beethoven's Five Secrets - One Republic"

Stars and Dust in Corona Australis - Astronomy picture of the day - 2018 September 20

Stars and Dust in Corona Australis 
Image Credit & Copyright: Josep Drudis

Explanation: Cosmic dust clouds and young, energetic stars inhabit this telescopic vista, less than 500 light-years away toward the northern boundary of Corona Australis, the Southern Crown. The dust clouds effectively block lightfrom more distant background stars in the Milky Way. But the striking complex of reflection nebulae cataloged as NGC 6726, 6727, and IC 4812 produce a characteristic color as blue light from the region's young, hot stars isreflected by the cosmic dust. The dust also obscures from view stars still in the process of formation. At top right, smaller yellowish nebula NGC 6729 bends around young variable star R Coronae Australis. Near it, glowing arcs and loops shocked by outflows from embedded newborn stars are identified as Herbig-Haro objects. On the sky this field of view spans about 1 degree. That corresponds to almost 9 light-years at the estimated distance of the nearby star forming region.

Cocoon Nebula Deep Field - Astronomy picture of the day - 2018 September 19

Cocoon Nebula Deep Field 
Image Credit & Copyright: Marcel Drechsler (Baerenstein Obs.)

Explanation: Inside the Cocoon Nebula is a newly developing cluster of stars. The cosmic Cocoon on the upper right also punctuates a long trail of obscuring interstellar dust clouds to its left. Cataloged as IC 5146, the beautiful nebula is nearly 15 light-years wide, located some 3,300 light years away toward the northern constellation of the Swan (Cygnus). Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by young, hot stars and blue, dust-reflected starlight at the edge of a nearly invisible molecular cloud. In fact, the bright star near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it slowly clears out a cavity in the molecular cloud's star forming dust and gas. This exceptionally deep color view of the Cocoon Nebula traces tantalizing features within and surrounding the dusty stellar nursery.

Cosmic Collision Forges Galactic Ring - Astronomy picture of the day - 2018 September 17

Cosmic Collision Forges Galactic Ring  Image Credit: X-ray: Chandra (NASA, CXC, INAF, A. Wolter et al.); Optical: Hubble (NASA, STScI) Explanation: How could a galaxy become shaped like a ring? The rim of the blue galaxy pictured on the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. That galaxy, AM 0644-741, is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide, they pass through each other -- their individual stars rarely come into contact. The ring-like shape is the result of the gravitational disruption caused by an entire small intruder galaxy passing through a large one. When this happens, interstellar gas and dust become condensed, causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond. The likely intruder galaxy is on the left of this combined image from Hubble (visible) and Chandra (X-ray) space telescopes. X-ray light is shown in pink and depicts places where energetic black holes or neutron stars, likely formed shortly after the galaxy collision, reside.

Ravel - "Bolero" - (Prequell Rework) - Video - Music

"Boléro"

A Solar Filament Erupts - Astronomy picture of the day - 2018 September 16

A Solar Filament Erupts 
Image Credit: NASA's GSFC, SDO AIA Team

Explanation: What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space producing an energetic Coronal Mass Ejection (CME). The filament had been held up for days by the Sun's ever changing magnetic field and the timing of the eruption was unexpected. Watched closely by the Sun-orbiting Solar Dynamics Observatory, the resulting explosion shotelectrons and ions into the Solar System, some of which arrived at Earth three days later and impacted Earth's magnetosphere, causing visible aurorae. Loops of plasma surrounding an active region can be seen above the erupting filament in the featured ultraviolet image. Although the Sun is now in a relatively inactive state of its 11-year cycle, unexpected holes have opened in the Sun's corona allowing an excess of charged particles to stream into space. As before, these charged particles are creating auroras.

Mont Blanc, Meteor, and Milky Way - Astronomy picture of the day - 2018 September 15

Mont Blanc, Meteor, and Milky Way 
Image Credit & Copyright: Adrien Mauduit

Explanation: Snowy Mont Blanc is near the center of this atmospheric night skyscape. But high, thin clouds fogged the skies at the photographer's location, looking south toward Europe's highest peak from the southern Swiss Alps. Still, the 13 second exposure finds the faint star fields and dark rifts of the Milky Way above the famous white mountain. Bloated by the mist, bright planet Saturn and Antares (right), alpha star of Scorpius, shine through the clouds to flank the galaxy's central bulge. The high-altitude scene is from the rewarding night of August 12/13, so it also includes the green trail of a Perseid meteor shooting along the galactic plane.

Ice Halos at Yellowknife - Astronomy picture of the day - 2018 September 14

Ice Halos at Yellowknife 
Image Credit & Copyright: Stephen Bedingfield

Explanation: You've probably seen a circle around the Sun before. More common than rainbows, ice halos, like a 22 degree circular halo for example, can be easy to spot, especially if you can shade your eyes from direct sunlight. Still it's rare to see such a diverse range of ice halos, including sundogs, tangent, infralateral, and Parry arcs, all found in this snapshot from planet Earth. The picture was quickly taken in the late morning of September 4 from Yellowknife, Northwest Territories, Canada. The beautiful patterns are generated as sunlight (or moonlight) is reflected and refracted in six-sided water ice crystals in Earth's atmosphere. Of course, atmospheric ice halos in the skies ofother worlds are likely to be different.

Real Time Perseid - Astronomy picture of the day - 2018 September 13

Real Time Perseid 
Video Credit & Copyright: Till Credner, AlltheSky.com

Explanation: Bright meteors and dark night skies made this year's Perseid meteor shower a great time for a weekend campout. And while packing away their equipment, skygazers at a campsite in the mountains of southern Germany found at least one more reason to linger under the stars, witnessing this brief but colorful flash with their own eyes. Presented as a 50 frame gif, the two second long video was captured during the morning twilight of August 12. In real time it shows the development of the typical green train of a bright Perseid meteor. A much fainter Perseid is just visible farther to the right. Plowing through Earth's atmosphere at 60 kilometers per second, Perseids are fast enough to excite the characteristic green emission of atomic oxygen at altitudes of 100 kilometers or so.

Lunations - Astronmy picture of the day - 2018 September 12

Lunations 
Video Credit: Data: Lunar Reconnaissance Orbiter ; Animation: NASA's Scientific Visualization Studio;
Music: The Blue Danube (Johann Strauss II)

Explanation: Our Moon's appearance changes nightly. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The featured video animates images taken by NASA's Moon-orbiting Lunar Reconnaissance Orbiter to show all 12 lunations that appear this year, 2018. A single lunation describes one full cycle of our Moon, including all of its phases. A full lunation takes about 29.5 days, just under a month (moon-th). As each lunation progresses, sunlight reflects from the Moon at different angles, and so illuminates different features differently. During all of this, of course, the Moon always keeps the same face toward the Earth. What is less apparent night-to-night is that the Moon's apparent size changes slightly, and that a slight wobble called a libration occurs as the Moon progresses along its elliptical orbit.

Non, cette étude n’a pas conclu qu’un verre d’alcool, c’est trop ! - Santé/médecine

À la fin du mois d’août, une recherche faisait le tour du monde avec des manchettes on ne peut plus éloquentes : un seul verre d’alcool par jour, c’est déjà dangereux pour la santé. En fait, l'étude ne dit pas tout à fait ça.

Les conclusions générales de cette méta-analyse n’étonnent pas : la consommation excessive d’alcool accroît bel et bien le risque de nombreux problèmes, allant de la haute pression sanguine jusqu’au cancer du foie en passant par des pertes de mémoire (on répertorie 23 « troubles de santé » au total).

Le problème réside dans l’attention qui a été accordée à l’affirmation « un seul verre par jour, c’est trop ». Une affirmation qui n’est pas le résultat d’exagérations des médias : c’est ce qu’on peut lire dans le communiqué de presse (« il n’existe pas de niveau sécuritaire d’alcool ») et dans la recherche elle-même.

Verdict :

Bien qu’il ne soit pas faux de dire que « le niveau de consommation qui minimise les pertes de santé est de zéro », la différence d’impact entre zéro verre et un verre est tellement minime qu’elle ne mérite pas de devenir le message central d’une méta-analyse de cette ampleur. Les chercheurs ont dégagé bien davantage de données sur les impacts de la consommation excessive d’alcool.

Science-Presse

Milky Way over Troll's Tongue - Astronomy picture of the day - 2018 September 11

Milky Way over Troll's Tongue 
Image Credit & Copyright: Ruslan Merzlyakov (RMS Photography)

Explanation: You have to take a long hike to see the Troll's Tongue -- ten hours over rocky terrain. And in this case, it took three trips to capture the landform below a clear night sky. Trolltunga itself is a picturesque rock protrusionextending about 700 meters over mountainous cliffs near Lake Ringedalsvatnet in Norway. The overhang is made of billion-year-old Precambrian bedrock that was carved out by glaciers during an ice-age about 10,000 years ago. Thefeatured picture is a composite of two exposures, a 15-second image of the foreground Earth followed 40 minutes later by an 87-second exposure of the background sky. Thousands of discernable stars dot the backdrop starscape in addition to billions of unresolved stars in the nearly vertical band of our Milky Way Galaxy.

Along the Western Veil - Astronomy picture of the day - 2018 September 6

Along the Western Veil 
Image Credit & Copyright: Data - Steve Milne & Barry Wilson, Processing - Steve Milne

Explanation: Delicate in appearance, these filaments of shocked, glowing gas, are draped across planet Earth's sky toward the constellation of Cygnus. They form the western part of the Veil Nebula. The Veil Nebula itself is a largesupernova remnant, an expanding cloud born of the death explosion of a massive star. Light from the original supernova explosion likely reached Earth over 5,000 years ago. Blasted out in the cataclysmic event, the interstellar shock wave plows through space sweeping up and exciting interstellar material. The glowing filaments are really more like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. Also known as the Cygnus Loop, the Veil Nebula now spans nearly 3 degrees or about 6 times the diameter of the full Moon. While that translates to over 70 light-years at its estimated distance of 1,500 light-years, this telescopic two panel mosaic image of the western portion spans about half that distance. Brighter parts of the western Veil are recognized as separate nebulae, including The Witch's Broom (NGC 6960) along the top of this view andPickering's Triangle (NGC 6979) below and left.

NGC 3682: Sideways Spiral Galaxy - Astronomy picture of the day - 2018 September 5

NGC 3682: Sideways Spiral Galaxy 
Image Credit & Copyright: Data: Paul Gardner, Great Basin Observatory; Processing: Rogelio Bernal Andreo (DeepSkyColors.com)

Explanation: What do spiral galaxies look like sideways? Featured is a sharp telescopic view of a magnificent edge-on spiral galaxy NGC 3628, a puffy galactic disk divided by dark dust lanes. Of course, this deep galactic portraitputs some astronomers in mind of its popular moniker, The Hamburger Galaxy. The tantalizing island universe is about 100,000 light-years across and 35 million light-years away in the northern springtime constellation Leo. NGC 3628shares its neighborhood in the local Universe with two other large spirals M65 and M66 in a grouping otherwise known as the Leo Triplet. Gravitational interactions with its cosmic neighbors are likely responsible for the extended flare and warp of this spiral's disk.

Franz Schubert - "Sérénade" - Video - Music

"Sérénade"

Moon behind Lava Fountain - Astronomy picture of the day - 2018 September 4

Moon behind Lava Fountain 
Image Credit & Copyright: Marcella Giulia Pace (GreenFlash.Photo)

Explanation: What's happened to the Moon? Nothing, but something has happened to the image of the Moon. The heat from a volcanic lava fountain in the foreground has warmed and made turbulent the air nearby, causing passing light to refract differently than usual. The result is a lava plume that appears to be melting the Moon. The featured picture was taken as the full Sturgeon Moon was setting behind Mt. Etna as it erupted in Italy about one week ago. The picture is actually a composite of two images, one taken right after the other, with the same camera and lens. The first image was a quick exposure to capture details of the setting Moon, while the second exposure, taken after the Moon set a few minutes later, was longer so as to capture details of the faint lava jets. From our Earth, we can only see the Sun, Moon, planets, and stars as they appear through the distortion of the Earth's atmosphere. This distortion can not only change the images of familiar orbs into unusual shapes, it can --unexpectedly at times -- delay sunset and moonset by several minutes.

Ciel verdâtre sous orage - Annonce de phénomènes violents ? - Météorologie

Si le ciel prend une couleur verdâtre à l’approche d’un orage, est-ce là une indication que des phénomènes violents vont se produire, comme des tornades ou des gros grêlons par exemple ? Beaucoup de personnes associent la couleur verdâtre d’un ciel orageux à l’arrivée imminente de phénomènes intenses. Cependant, est-ce une réalité physiquement démontrée ou cela tient-il plus de la légende urbaine ?

Parfois, lors de l’arrivée d’un orage, le ciel prend une couleur verdâtre. Il existe un discours populaire selon lequel cette coloration céleste serait l’indice que des phénomènes particulièrement violents sont sur le point de se produire. Sont notamment évoquées les tornades et la grosse grêle. Par exemple, dans les régions très sujettes aux tornades – comme le centre des États-Unis – l’apparition d’un ciel verdâtre devrait encourager les habitants à se mettre en sécurité dans leur cave ou dans un abri adapté. Ces associations se sont progressivement propagées comme des sortes de légendes urbaines, sans que l’on puisse facilement en démêler le vrai du faux.

.../...

Science Post

Une comète se rapproche de la Terre - Science - Espace

Découverte en 1900 par l’astronome français Michel Giacobini, puis redécouverte en 1913 par l’astronome allemand Ernst Zinner, la comète 21P/Giacobini-Zinner s’est formée au-delà de “la ligne de gel” (ou de glace). Cette dernière est située après les orbites de Mars et de Jupiter, et effectue un tour du Soleil en 6,6 ans environ. Cette année, son orbite l’amènera non loin de notre planète. Le 10 septembre prochain, elle se positionnera à environ 58 millions de km. Sa magnitude étant estimée à 7, vous ne pourrez observer l’objet à l’œil nu, mais une simple paire de jumelles devrait suffire.

Comment la trouver ? La comète, qui se déplace actuellement dans l’espace à une vitesse de plus de 50 000 kilomètres à l’heure, traversera au cours des prochaines nuits les constellations du Cocher, des Gémeaux et de la Licorne. Pour mettre toutes les chances de votre côté, sortez vos jumelles ou votre télescope le 10 septembre prochain, entre minuit et le petit matin. Éloignez-vous également – il en va de soi – de toute pollution lumineuse, en espérant également un ciel clément. La comète d’un peu plus d’un kilomètre de diamètre devrait alors apparaître, teintée d’un bleu vert scintillant.

Science-Post

Aurora around Saturn's North Pole - Astronomy picture of the day - 2018 September 3

Aurora around Saturn's North Pole 
Image Credit: NASA, ESA, Hubble, OPAL Program, J. DePasquale (STScI), L. Lamy (Obs. Paris)

Explanation: Are Saturn's auroras like Earth's? To help answer this question, the Hubble Space Telescope and the Cassini spacecraft monitored Saturn's North Pole simultaneously during Cassini's final orbits around the gas giant in September 2017. During this time, Saturn's tilt caused its North Pole to be clearly visible from Earth. The featured image is a composite of ultraviolet images of aurora and optical images of Saturn's clouds and rings, all taken recently by Hubble. Like on Earth, Saturn's northern auroras can make total or partial rings around the pole. Unlike on Earth, however, Saturn's auroras are frequently spirals -- and more likely to peak in brightness just before midnight and dawn. In contrast to Jupiter's auroras, Saturn's auroras appear better related to connecting Saturn's internal magnetic field to the nearby, variable, solar wind. Saturn's southern auroras were similarly imaged back in 2004 when theplanet's South Pole was clearly visible to Earth.

A Powerful Solar Flare - Astronomy picture of the day - 2018 September 2

A Powerful Solar Flare 
Video Credit: SOHO Consortium, LASCO, ESA, NASA

Explanation: It was one of the most powerful solar flares in recorded history. Occurring in 2003 and seen across the electromagnetic spectrum, the Sun briefly became over 100 times brighter in X-rays than normal. The day after thistremendous X 17 solar flare -- and subsequent Coronal Mass Ejection (CME) -- energetic particles emitted from the explosions struck the Earth, creating auroras and affecting satellites. The spacecraft that took these frames -- SOHO-- was put in a turtle-like safe mode to avoid further damage from this and subsequent solar particle storms. The featured time-lapse movie condenses into 10 seconds events that occurred over 4 hours. The CME, visible around the central sun-shade, appears about three-quarters of the way through the video, while frames toward the very end are progressively noisier as protons from the explosions strike SOHO's LASCO detector. One this day in 1859, the effects of an even more powerful solar storm caused telegraphs on Earth to spark in what is known as the Carrington Event. Powerful solar storms such as these may create beautiful aurora-filled skies, but they also pose a real danger as they can damage satellites and even power grids across the Earth.

Aerosol Earth - Astronomy picture of the day - 2018 September 1

Aerosol Earth 
Model Visualization Credit: NASA Earth Observatory, GEOS FP, Joshua Stevens

Explanation: On August 23, 2018 the identification and distribution of aerosols in the Earth's atmosphere is shown in this dramatic, planet-wide visualization. Produced in real time, the Goddard Earth Observing System Forward Processing (GEOS FP) model relies on a combination of Earth-observing satellite and ground-based data to calculate the presence of types of aerosols, tiny solid particles and liquid droplets, as they circulate above the entire planet. This August 23rd model shows black carbon particles in red from combustion processes, like smoke from the fires in the United States and Canada, spreading across large stretches of North America and Africa. Sea salt aerosols are in blue, swirling above threatening typhoons near South Korea and Japan, and the hurricane looming near Hawaii. Dust shown in purple hues is blowing over African and Asian deserts. The location of cities and towns can be found from the concentrations of lights based on satellite image data of the Earth at night.