APOD Wall Calendar 2015 General: All Topics

APOD Wall Calendar
2015
General: All Topics
This image:
© Fred Vanderhaven
A Solar Filament Erupts
Credit: NASA's GSFC, SDO AIA Team
Explanation: What's happened to our Sun? Nothing very unusual -- it just threw a filament. At the end of last month, 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 shot electrons 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 ultraviolet image. If you missed this auroral display please do not despair -- over the next two years our Sun will
be experiencing a solar maximum of activity which promises to produce more CMEs that induce more Earthly auroras. APOD: 2012 September 17
2014
January
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December
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June
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From the Northern to the Southern Cross
© Nicholas Buer
Explanation: There is a road that connects the Northern to the Southern Cross but you have to be at the right place and time to see it. The road, as pictured above, is actually the central band of
our Milky Way Galaxy; the right place, in this case, is dark Laguna Cejar in Salar de Atacama of Northern Chile; and the right time was in early October, just after sunset. Many sky wonders were
captured then, including the bright Moon, inside the Milky Way arch; Venus, just above the Moon; Saturn and Mercury, just below the Moon; the Large and Small Magellanic Clouds satellite
galaxies, on the far left; red airglow near the horizon on the image left; and the lights of small towns at several locations across the horizon. One might guess that composing this 30-image
panorama would have been a serene experience, but for that one would have required earplugs to ignore the continued brays of wild donkeys. APOD: 2014 January 27
January 2015
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Monday
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Quadrantids meteor shower
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Earth closest to Sun
Quadrantids meteor shower
The Pleiades Deep and Dusty
Explanation: The well known Pleiades star cluster is slowly destroying part of a passing cloud of gas and dust. The Pleiades is the brightest open cluster of stars on Earth's sky and can be seen from
almost any northerly location with the unaided eye. The passing young dust cloud is thought to be part of Gould's belt, an unusual ring of young star formation surrounding the Sun in the local Milky
Way Galaxy. Over the past 100,000 years, part of Gould's belt is by chance moving right through the older Pleiades and is causing a strong reaction between stars and dust. Pressure from the stars' light
significantly repels the dust in the surrounding blue reflection nebula, with smaller dust particles being repelled more strongly. A short-term result is that parts of the dust cloud have become
filamentary and stratified, as seen in the above deep-exposure image. Image Credit & Copyright: David Lane. APOD: 2014 February 25 .
February 2015
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Dawn approaches Ceres
Saturday
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Jupiter brightest
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Venus nearest Mars
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Globules in the Running Chicken Nebula
© Fred Vanderhaven
Explanation: The eggs from this chicken may form into stars. The above pictured emission nebula, cataloged as IC 2944, is called the Running Chicken Nebula for the shape of its greater appearance.
The image was taken recently from Siding Spring Observatory in Australia and presented in scientifically assigned colors. Seen near the center of the image are small, dark molecular clouds rich in
obscuring cosmic dust. Called Thackeray's Globules for their discoverer, these "eggs" are potential sites for the gravitational condensation of new stars, although their fates are uncertain as they are
also being rapidly eroded away by the intense radiation from nearby young stars. Together with patchy glowing gas and complex regions of reflecting dust, these massive and energetic stars form the
open cluster Collinder 249. This gorgeous skyscape spans about 70 light-years at the nebula's estimated 6,000 light-year distance. APOD: 2014 March 5
March 2015
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Total Solar Eclipse
Equinox
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Saturn in Blue and Gold
Credit: Cassini Imaging Team
Explanation: Why is Saturn partly blue? The above picture of Saturn approximates what a human would see if hovering close to the giant ringed world. The above picture was taken in 2006 March by
the robot Cassini spacecraft now orbiting Saturn. Here Saturn's majestic rings appear directly only as a thin vertical line. The rings show their complex structure in the dark shadows they create on the
image left. Saturn's fountain moon Enceladus, only about 500 kilometers across, is seen as the bump in the plane of the rings. The northern hemisphere of Saturn can appear partly blue for the same
reason that Earth's skies can appear blue -- molecules in the cloudless portions of both planet's atmospheres are better at scattering blue light than red. When looking deep into Saturn's clouds,
however, the natural gold hue of Saturn's clouds becomes dominant. It is not known why southern Saturn does not show the same blue hue -- one hypothesis holds that clouds are higher there. It is
also not known why Saturn's clouds are colored gold. Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA. APOD: 2014 April 13 .
April 2015
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Monday
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Wednesday
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Total Lunar Eclipse
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Lyrids Meteor Shower
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Lyrids Meteor Shower
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A Scorpius Sky Spectacular
Explanation: If Scorpius looked this good to the unaided eye, humans might remember it better. Scorpius more typically appears as a few bright stars in a well-known but rarely pointed out zodiacal
constellation. To get a spectacular image like this, though, one needs a good camera, color filters, and a digital image processor. To bring out detail, the above image not only involved long duration
exposures taken in several colors, but one exposure in a very specific red color emitted by hydrogen. The resulting image shows many breathtaking features. Vertically across the image left is part of the
plane of our Milky Way Galaxy. Visible there are vast clouds of bright stars and long filaments of dark dust. Jutting out diagonally from the Milky Way in the image center are dark dust bands known as the
Dark River. This river connects to several bright stars on the right that are part of Scorpius' head and claws, and include the bright star Antares. Above and right of Antares is an even brighter planet Jupiter.
Numerous red emission nebulas and blue reflection nebulas are visible throughout the image. Scorpius appears prominently in southern skies after sunset during the middle of the year. Image Credit &
Copyright: Stéphane Guisard, TWAN. 2014 May 4 .
May 2015
Sunday
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Monday
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Tuesday
Wednesday
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Eta Aquariids Meteor Shower
Eta Aquariids Meteor Shower
Thursday
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Saturn brightest
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Image Credit: NASA, JPL-Caltech, MSSS
Martian Anniversary Selfie
Explanation: June 24th 2014 marked the
first full Martian year of the Curiosity
Rover's exploration of the surface of
the Red Planet. That's 687 Earth days or
669 sols since its landing on August 5,
2012. To celebrate, consider this selfportrait of the car-sized robot posing
next to a rocky outcrop dubbed
Windjana, its recent drilling and
sampling site. The mosaicked selfie was
constructed with frames taken this April
and May using the rover's Mars Hand
Lens Imager (MAHLI), intended for
close-up work and mounted at the end
of the rover's robotic arm. The MAHLI
frames used exclude sections that show
the arm itself and so MAHLI and the
robotic arm are not seen. Famous for
panoramic views, the rover's Mastcam
is visible though, on top of the tall mast
staring toward the left and down at the
drill hole. APOD: 2014 June 27
June 2015
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Solstice
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Venus nearest Jupiter
Auroras over Northern Canada
Explanation: Gusting solar winds and blasts of charged particles from the Sun resulted in several rewarding nights last December for those anticipating auroras. The above image captured dramatic
auroras stretching across a sky near the town of Yellowknife in northern Canada. The auroras were so bright that they not only inspired awe, but were easily visible on an image exposure of only 1.3
seconds. A video taken concurrently shows the dancing sky lights evolving in real time as tourists, many there just to see auroras, respond with cheers. The conical dwellings on the image right are
teepees, while far in the background, near the image center, is the constellation of Orion. Image Credit & Copyright: Kwon, O Chul (TWAN). APOD: 2014 July 14 .
July 2015
Sunday
Monday
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Venus nearest Jupiter
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Earth furthest from Sun
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New Horizons passes Pluto
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Delta Aquariids Meteor Shower
Delta Aquariids Meteor Shower
Venus near Jupiter
M74: The Perfect Spiral
Credit: NASA, ESA, and the Hubble Heritage (STScI / AURA)- ESA / Hubble Collaboration
Acknowledgment: R. Chandar (Univ. Toledo) and J. Miller (Univ. Michigan)
Explanation: If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 32 million light-years away toward the constellation Pisces,
M74 presents a gorgeous face-on view. Classified as an Sc galaxy, the grand design of M74's graceful spiral arms are traced by bright blue star clusters and dark cosmic dust lanes. Constructed from
image data recorded in 2003 and 2005, this sharp composite is from the Hubble Space Telescope's Advanced Camera for Surveys. Spanning about 30,000 light-years across the face of M74, it
includes exposures recording emission from hydrogen atoms, highlighting the reddish glow of the galaxy's large star-forming regions. Recently, many astronomers are tracking a bright supernova
that has been seen in M74. APOD: 2013 August 11 .
August 2015
Sunday
Monday
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Perseids Meteor Shower
Perseids Meteor Shower
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Venus nearest Mars
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Venus nearest Mars
M2-9: Wings of a Butterfly Nebula
Credit: Hubble Legacy Archive, NASA, ESA - Processing: Judy Schmidt
Explanation: Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9
pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes. The expended gas frequently forms an impressive display called
a planetary nebula that fades gradually over thousand of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but
incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance.
Much remains unknown about the physical processes that cause planetary nebulae. APOD: 2013 September 15 .
September 2015
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Partial Solar Eclipse
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Equinox
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Total Lunar Eclipse
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Horsehead and Orion Nebulas
© Roberto Colombari & Federico Pelliccia
Explanation: The dark Horsehead Nebula and the glowing Orion Nebula are contrasting cosmic vistas. Adrift 1,500 light-years away in one of the night sky's most recognizable constellations, they
appear in opposite corners of the above stunning mosaic. The familiar Horsehead nebula appears as a dark cloud, a small silhouette notched against the long red glow at the lower left. Alnitak is the
easternmost star in Orion's belt and is seen as the brightest star to the left of the Horsehead. Below Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. The
magnificent emission region, the Orion Nebula (aka M42), lies at the upper right. Immediately to its left is a prominent reflection nebula sometimes called the Running Man. Pervasive tendrils of
glowing hydrogen gas are easily traced throughout the region. APOD: 2013 October 29 .
October 2015
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Mars nearest Jupiter
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Orionids Meteor Shower
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Venus nearest Jupiter
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Venus nearest Jupiter
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Venus near Mars & Jupiter
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Orionids Meteor Shower
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Credit: ESA / Rosetta / MPS for OSIRIS Team; MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Rosetta's Rendezvous
Explanation: On 2014 August 3rd, the Rosetta spacecraft's
narrow angle camera captured this stunning image of the
nucleus of Comet 67P/Churyumov-Gerasimenko. After 10
years and 6.5 billion kilometers of travel along gravity assist
trajectories looping through interplanetary space, Rosetta had
approached to within 285 kilometers of its target. The curious
double-lobed shape of the nucleus is revealed in amazing detail
at an image resolution of 5.3 meters per pixel. About 4
kilometers across, the comet nucleus is presently just over 400
million kilometers from Earth, between the orbits of Jupiter
and Mars. Now the first spacecraft to achieve a delicate orbit
around a comet, Rosetta will swing to within 50 kilometers and
closer in the coming weeks, identifiying candidate sites for
landing its probe Philae later in 2014. APOD: 2014 August 7
November 2015
Sunday
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Venus nearest Mars
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Leonids Meteor Shower
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Leonids Meteor Shower
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Quantum Streampunk Fantasy Fractal Landscape
© Jos Leys (Mathematical Imagery), Ultra Fractal
Explanation: What strange world is this? Pictured above is no real place but rather a purely mathematical visualization of a generalization of a fractal into three dimensions. Classical fractal
diagrams are typically confined to the two dimensions inherent in the complex number plane, demarking regions where an iterative function diverges. Recently explored additions expand the
Mandelbrot set of fractals to three dimensions with prescriptions dubbed Mandelbox and Mandelbulb sets. The results are often visually stunning creations of virtual worlds with limitless detail,
some of which you can fly through. Pictured above is one such mathematical fantasy, possibly reminiscent of some sort of steam-punkian, quantum-mechanical landscape. Image Credit &
Copyright: Jos Leys (Mathematical Imagery), Ultra Fractal. APOD: 2013 December 30 .
December 2015
Sunday
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Monday
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Tuesday
Wednesday
Thursday
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Saturday
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Moon near Venus
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Geminids Meteor Shower
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Geminids Meteor Shower
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Solstice
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Saturn's Iapetus: Painted Moon
Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Explanation: What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark as coal, while others are as bright as ice. The composition of the dark material is unknown, but
infrared spectra indicate that it possibly contains some dark form of carbon. Iapetus also has an unusual equatorial ridge that makes it appear like a walnut. To help better understand this seemingly
painted moon, NASA directed the robotic Cassini spacecraft orbiting Saturn to swoop within 2,000 kilometers in 2007. Pictured above, from about 75,000 kilometers out, Cassini's trajectory allowed
unprecedented imaging of the hemisphere of Iapetus that is always trailing. A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of
similar size. The dark material is seen increasingly coating the easternmost part of Iapetus, darkening craters and highlands alike. Close inspection indicates that the dark coating typically faces the moon's
equator and is less than a meter thick. A leading hypothesis is that the dark material is mostly dirt leftover when relatively warm but dirty ice sublimates. An initial coating of dark material may have been
effectively painted on by the accretion of meteor-liberated debris from other moons. This and other images from Cassini's Iapetus flyby are being studied for even greater clues. Image Credit: Cassini
Imaging Team, SSI, JPL, ESA, NASA. APOD: 2012 January 13 .
2016
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Since June 1995, Astronomy Picture of the Day® (APOD) has featured a different image or photograph of our
fascinating universe along with a brief explanation written by a professional astronomer. The website was
created by and continues to be edited by Robert J. Nemiroff and Jerry T. Bonnell.
http://apod.nasa.gov/
This free downloadable calendar features images that have appeared on APOD. Moon phases and
astronomical event dates are in UTC. The editors thank the many astrophotographers and professional
astronomers whose images are submitted to and appear on APOD. The presentation of Astronomy Picture
of the Day ® from NASA is a service of ASD at NASA / GSFC & Michigan Tech. U.
The creation of APOD is supported, in part, by a grant from NASA, and by virtual space explorers like you.