Halloween and the Ghost Head Nebula

Halloween’s origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With a modern calendar however, even though Halloween occurs tomorrow, the real cross-quarter day will occur next week. Another cross-quarter day is Groundhog Day. Halloween’s modern celebration retains historic roots in dressing to scare away the spirits of the dead. Perhaps a fitting tribute to this ancient holiday is this view of the Ghost Head Nebula taken with the Hubble Space Telescope. Similar to the icon of a fictional ghost, NGC 2080 is actually a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way Galaxy. The Ghost Head Nebula spans about 50 light-years and is shown in representative colors. via NASA http://ift.tt/2fjzIda

Propeller Shadows on Saturn’s Rings

What created these unusually long shadows on Saturn’s rings? The dark shadows — visible near the middle of the image — extend opposite the Sun and, given their length, stem from objects having heights up to a few kilometers. The long shadows were unexpected given that the usual thickness of Saturn’s A and B rings is only about 10 meters. After considering the choppy but elongated shapes apparent near the B-ring edge, however, a leading theory has emerged that some kilometer-sized moonlets exist there that have enough gravity to create even larger vertical deflections of nearby small ring particles. The resulting ring waves are called propellers, named for how they appear individually. It is these coherent groups of smaller ring particles that are hypothesized to be casting the long shadows. The featured image was taken by the robotic Cassini spacecraft currently orbiting Saturn. The image was captured in 2009, near Saturn’s equinox, when sunlight streamed directly over the ring plane and caused the longest shadows to be cast. via NASA http://ift.tt/2eFVy6g

Clouds Near Jupiters South Pole from Juno

What’s happening near the south pole of Jupiter? Recent images sent back by NASA’s robotic Juno spacecraft are showing an interesting conglomeration of swirling clouds and what appear to be white ovals. Juno arrived at Jupiter in July and is being placed into a wide, looping orbit that will bring it near the gas giant — and over its poles — about twice a month. The featured image is a composite taken by JunoCam and post-processed by a digitally savvy citizen scientist. White ovals have been observed elsewhere on Jupiter and are thought to be giant storm systems. They have been observed to last for years, while typically showing Category 5 wind speeds of around 350 kilometers per hour. Unlike Earthly cyclones and hurricanes where high winds circle regions of low pressure, white ovals on Jupiter show rotational directions indicating that they are anticylones — vortices centered on high pressure regions. Juno will continue to orbit Jupiter over thirty more times while recording optical, spectral, and gravitational data meant to help determine Jupiter’s structure and evolution. via NASA http://ift.tt/2eHnAz7

Eagle Aurora over Norway

What’s that in the sky? An aurora. A large coronal mass ejection occurred on our Sun five days before this 2012 image was taken, throwing a cloud of fast moving electrons, protons, and ions toward the Earth. Although most of this cloud passed above the Earth, some of it impacted our Earth’s magnetosphere and resulted in spectacular auroras being seen at high northern latitudes. Featured here is a particularly photogenic auroral corona captured above Grotfjord, Norway. To some, this shimmering green glow of recombining atmospheric oxygen might appear as a large eagle, but feel free to share what it looks like to you. Although now past Solar Maximum, our Sun continues to show occasional activity creating impressive auroras on Earth visible only last week. via NASA http://ift.tt/2eu9S4j

M45: The Pleiades Star Cluster

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 even from the heart 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 image was a long duration exposure taken last month from Namibia and covers a sky area many times the size of the full moon. Also known as the Seven Sisters and M45, the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus). A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six stars visible to the unaided eye. The actual number of visible Pleiades stars, however, may be more or less than seven, depending on the darkness of the surrounding sky and the clarity of the observer’s eyesight. via NASA http://ift.tt/2el3RF8

The Antlia Cluster of Galaxies

Galaxies dot the sky in this impressively wide and deep image of the Antlia Cluster. The third closest cluster of galaxies to Earth after Virgo and Fornax, the Antlia cluster is known for its compactness and its high fraction of elliptical galaxies over (spirals. Antlia, cataloged as Abell S0636, spans about 2 million light years and lies about 130 million light years away toward the constellation of the Air Pump (Antlia). The cluster has two prominent galaxy groups – bottom center and upper left — among its over 200 galactic members, but no single central dominant galaxy. The vertical red ribbon of gas on the left is thought related to the foreground Antlia supernova remnant and not associated with the cluster. The featured image composite, taken from New Zealand, resulted from 150+ hours of exposures taken over six months. via NASA http://ift.tt/2egQ4iQ

Cylindrical Mountains on Venus

What could cause a huge cylindrical mountain to rise from the surface of Venus? Such features that occur on Venus are known as coronas. Pictured here in the foreground is 500-kilometer wide Atete Corona found in a region of Venus known as the Galindo. The featured image was created by combining multiple radar maps of the region to form a computer-generated three-dimensional perspective. The series of dark rectangles that cross the image from top to bottom were created by the imaging procedure and are not real. The origin of massive coronas remains a topic of research although speculation holds they result from volcanism. Studying Venusian coronas help scientists better understand the inner structure of both Venus and Earth. via NASA http://ift.tt/2e9hMOr

Herschel s Orion

This dramatic image peers within M42, the Orion Nebula, the closest large star-forming region. Using data at infrared wavelengths from the Herschel Space Observatory, the false-color composite explores the natal cosmic cloud a mere 1,500 light-years distant. Cold, dense filaments of dust that would otherwise be dark at visible wavelengths are shown in reddish hues. Light-years long, the filaments weave together bright spots that correspond to regions of collapsing protostars. The brightest bluish area near the top of the frame is warmer dust heated by the hot Trapezium cluster stars that also power the nebula’s visible glow. Herschel data has recently indicated ultraviolet starlight from the hot newborn stars likely contributes to the creation of carbon-hydrogen molecules, basic building blocks of life. This Herschel image spans about 3 degrees on the sky. That’s about 80 light-years at the distance of the Orion Nebula. via NASA http://ift.tt/2efmMkj

Galaxies from the Altiplano

The central bulge of our Milky Way Galaxy rises over the northern Chilean Atacama altiplano in this postcard from planet Earth. At an altitude of 4500 meters, the strange beauty of the desolate landscape could almost belong to another world though. Brownish red and yellow tinted sulfuric patches lie along the whitish salt flat beaches of the Salar de Aguas Calientes region. In the distance along the Argentina border is the stratovolcano Lastarria, its peak at 5700 meters (19,000 feet). In the clear, dark sky above, stars, nebulae, and cosmic dust clouds in the Milky Way echo the colors of the altiplano at night. Extending the view across extragalactic space, the Large and Small Magellanic Clouds, satellite galaxies of the Milky Way, shine near the horizon through a faint greenish airglow. via NASA http://ift.tt/2dP2QJ4

Penumbral Lunar Eclipse

Does this Moon look a little different to you? Although shown in spectacular detail, the full face of Earth’s most familiar satellite appears slightly darker than usual, in particular on the upper left, because it is undergoing a penumbral lunar eclipse. The image was captured in Hong Kong, China, on September 16 when the Moon crossed through part of Earth’s shadow — but not the darkest where the Earth shades the entire Sun. A lunar eclipse can only occur during a full moon, and many know this particular full moon as the Harvest moon for its proximity to northern harvests. The next full moon will occur this coming Sunday. Some cultures refer to it as a Leaf Falling Moon, named for its proximity to northern autumn. The second full moon of the same month (“moonth”) is sometimes called a Blue moon; meanwhile, this month features a rare second new moon, an event known to some as a Black moon. via NASA http://ift.tt/2e14PWe