Astronomy Picture of the Day – Sentinels of the Arctic

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

Sentinels of the Arctic
Image Credit & Copyright: Niccolò Bonfadini

 

Explanation: Who guards the north? Judging from the above photograph, possibly giant trees covered in snow and ice. The featured picture was taken a few winters ago in Finnish Lapland where weather can include sub-freezing temperatures and driving snow. Surreal landscapes sometimes result, where common trees become cloaked in white and so appear, to some, as watchful aliens. Far in the distance, behind this uncommon Earthly vista, is a more common sight — a Belt of Venus that divided a darkened from sunlit sky as the Sun rose behind the photographer. Of course, in the spring, the trees thaw and Lapland looks much different.

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Astronomy Picture of the Day – A Solar Filament Erupts

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

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 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. Over the past week the number of sunspots visible on the Sun unexpectedly dropped to zero, causing speculation that the Sun has now passed a very unusual solar maximum, the time in the Sun’s 11-year cycle when it is most active.

Astronomy Picture of the Day – Pluto Resolved

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 July 15

Pluto Resolved
Image Credit & Copyright: NASA, Johns Hopkins Univ./APL, Southwest Research Inst.

 

Explanation: New Horizons has survived its close encounter with Pluto and has resumed sending back images and data. The robotic spacecraft reported back on time, with all systems working, and with the expected volume of data stored. Featured here is the highest resolution image of Pluto taken before closest approach, an image that really brings Pluto into a satisfying focus. At first glance, Pluto is reddish and has several craters. Toward the image bottom is a surprisingly featureless light-covered region that resembles an iconic heart, and mountainous terrain appears on the lower right. This image, however, is only the beginning. As more images and data pour in today, during the coming week, and over the next year, humanity’s understanding of Pluto and its moons will likely become revolutionized.

Astronomy Picture of the Day – New Horizons Passes Pluto and Charon

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 July 14


New Horizons Passes Pluto and Charon
Image Credit & Copyright: NASA, Johns Hopkins Univ./APL, Southwest Research Inst.

 

Explanation: Will the New Horizons spacecraft survive its closest approach to Pluto and return useful images and data? Humanity will know in a few hours. Regardless of how well it functions, New Horizon’s rapid speed will take it whizzing past Pluto and its moons today, with the time of closest approach being at 11:50 UT (7:50 am EDT). To better take images and data, though, the robotic spacecraft was preprogrammed and taken intentionally out of contact with the Earth until about 1:00 am UT July 15, which corresponds to about 9:00 pm EDT on July 14. Therefore, much of mankind will be holding its breath through this day, hoping that the piano-sized spacecraft communicates again with ground stations on Earth. Hopefully, at that time, New Horizons will begin beaming back new and enlightening data about a world that has remained remote and mysterious since its discovery 85 years ago. Featured above is a New Horizons composite image of the moon Charon (left) and Pluto (right) taken 3 days ago, already showing both worlds in unprecedented detail.

Astronomy Picture of the Day – New Horizons Launch to Pluto

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 July 12

New Horizons Launch to Pluto
Image Credit & Copyright: Ben Cooper

 

Explanation: Destination: Pluto. The New Horizons spacecraft roared off its launch pad at Cape Canaveral in Florida, USA in 2006 toward adventures in the distant Solar System. The craft is the fastest spaceships ever launched by humans, having passed the Moon only nine hours after launch, and Jupiter only a year later. After spending almost a decade crossing the Solar System, New Horizons will fly past Pluto on Tuesday. Pluto, officially a planet when New Horizons launched, has never been visited by a spacecraft or photographed up close. After Pluto, the robot spaceship will visit one or more Kuiper Belt Objects orbiting the Sun even further out than Pluto. Pictured, the New Horizons craft launches into space atop a powerful Atlas V rocket.

Astronomy Picture of the Day

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 July 7

 The Milky Way from a Malibu Sea Cave
Image Credit & Copyright: Jack Fusco

 
Explanation: What’s happening outside this cave? Nothing unexpected – it’s just the central band of our Milky Way Galaxy passing by. As the Earth turns, the band of our Galaxy appears to rotate and shift along the horizon. The featured image was taken by a photographer who professes a passion for locating sea caves, and who found this spectacular grotto in Leo Carrillo State Park near Malibu, California, USA. After some planning, he timed this single shot image through the 10-meter high cave entrance to show the Milky Way far in the distance. In the foreground, several rocks about one meter across are visible. Visible in the background starscape are millions of stars including the relatively bright and orange Antares, situated just to the right of the image center.

Astronomy Picture of the Day – Colorful Clouds Near Rho Ophiuchi

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 July 6

Colorful Clouds Near Rho Ophiuchi
Image Credit & Copyright: Markus Noller (Deep-Sky-Images)

 

Explanation: Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark. Antares, a red supergiant and one of the brighter stars in the night sky, lights up the yellow-red clouds on the lower center of the featured image. Rho Ophiuchi lies at the center of the blue nebula on the left. The distant globular cluster M4 is visible to the upper right of center. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum.

Astronomy Picture of the Day – Crystals on Mars

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 July 3

Crystals on Mars
Image Credit: NASA, JPL-Caltech, MSSS Explanation: This extreme close-up, a mosaic from the Mars Hand Lens Imager (MAHLI) on the Curiosity rover, spans a breathtaking 5 centimeters. It captures what appear to be elongated crystal shapes formed by the precipitation of minerals dissolved in water, a likely result of the evaporation of ancient lake or river from the Martian surface. Brushed by a dust removal tool and illuminated by white LEDs, the target rock named Mojave was found on the Pink Cliffs outcrop of the Pahrump Hills at the base of Mount Sharp. The MAHLI images were acquired on Curiosity’s sol 809, known on planet Earth as November 15, 2014. Of course, the inset 1909 Lincoln Cent image is provided for a comparison scale. Covered with Mars dust itself, the penny is a MAHLI calibration target attached to the rover.

Astronomy Picture of the Day – An Unusual Mountain on Asteroid Ceres

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 June 30

An Unusual Mountain on Asteroid Ceres
Image Credit: NASA, JPL-Caltech, UCLA, MPS/DLR/IDA

 

Explanation: What created this large mountain on asteroid Ceres? No one is yet sure. As if in anticipation of today being Asteroid Day on Earth, the robotic spacecraft Dawn in orbit around Ceres took the best yet image of an unusually tall mountain on the Asteroid Belt’s largest asteroid. Visible at the top of the featured image, the exceptional mountain rises about five kilometers up from an area that otherwise appears pretty level. The image was taken about two weeks ago from about 4,400 kilometers away. Although origin hypotheses for the mountain include volcanism, impacts, and plate tectonics, clear evidence backing any of these is currently lacking. Also visible across Ceres’ surface are some enigmatic light areas: bright spots whose origin and composition that also remain an active topic of investigation. Even though Dawn is expected to continue to orbit Ceres, officially dubbed a dwarf planet, for millions of years, the hydrazine fuel used to point Dawn’s communications antenna toward Earth is expected to run out sometime next year.

Astronomy Picture of the Day – Star Trails above Table Mountain

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2015 June 25

Star Trails above Table Mountain
Image Credit & Copyright:Eric Nathan

 

 

Explanation: Stars trail above and urban lights sprawl below in this moonlit nightscape from Cape Town, South Africa, planet Earth. The looming form of Table Mountain almost seems to hold terrestrial lights at bay while the stars circle the planet’s South Celestial Pole. This modern perspective on the natural night sky was captured in June 2014, the scene composed of over nine hundred, stacked 30 second exposures. The stunning result was chosen as the winner in the Against the Lights category, a selection from over 800 entries in The World at Night’s 2015 International Earth and Sky Photo Contest.