Blue Danube Analemma
Explanation: The Sun’s annual waltz through planet Earth’s sky forms a graceful curve known as an analemma. The analemma’s figure 8 shape is tipped vertically at far right in this well-composed fisheye view from Budapest, Hungary. Captured at a chosen spot on the western bank of the Danube river, the Sun’s position was recorded at 11:44 Central European Time on individual exposures over days spanning 2015 July 23 to 2016 July 4. Of course, on the northern summer solstice the Sun is at the top of the curve, but at the midpoints for the autumn and spring equinoxes. With snow on the ground, the photographer’s shadow and equipment bag also appear in the base picture used for the composite panorama, taken on 2016 January 7. On that date, just after the winter solstice, the Sun was leaving the bottom of the beautiful curve over the blue Danube.
Image Credit & Copyright: György Soponyai
Perseid Meteors Over China
Explanation: Comet dust rained down on planet Earth in August 2013, streaking through dark skies in the annual Perseid meteor shower. While enjoying the anticipated space weather above Zhangbei Prairie, Hebei Province, China, astronomer Xiang Zhan recorded a series of 10 second long exposures spanning four hours on the night of August 12/13 using a wide angle lens. Combining frames which captured 68 meteor flashes, he produced the above composite view of the Perseids of summer. Although the sand-sized comet particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky in the eponymous constellation Perseus. The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance.
The Perseid meteor shower will burst into light this August (2016), as Earth passes through the long trail left by Comet Swift-Tuttle — and this month, it’s slated to put on a spectacular show.
Image Credit & Copyright: Xiang Zhan (Beijing Planetarium)
M2-9: Wings of a Butterfly Nebula
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 thousands 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.
Image Credit: Hubble Legacy Archive, NASA, ESA – Processing: Judy Schmidt
Color the Universe
Explanation: Wouldn’t it be fun to color in the universe? If you think so, please accept this famous astronomical illustration as a preliminary substitute. You, your friends, your parents or children, can print it out or even color it digitally. While coloring, you might be interested to know that even though this illustration has appeared in numerous places over the past 100 years, the actual artist remains unknown. Furthermore, the work has no accepted name — can you think of a good one? The illustration, first appearing in a book by Camille Flammarion in 1888, is used frequently to show that humanity’s present concepts are susceptible to being supplanted by greater truths.
Image Credit: Unknown
Juno Approaching Jupiter
Explanation: Approaching over the north pole after nearly a five-year journey, Juno enjoys a perspective on Jupiter not often seen, even by spacecraft from Earth that usually swing by closer to Jupiter’s equator. Looking down toward the ruling gas giant from a distance of 10.9 million kilometers, the spacecraft’s JunoCam captured this image with Jupiter’s night side and orbiting entourage of four large Galilean moons on June 21. JunoCam is intended to provide close-up views of the gas giant’s cloudy zoned and belted atmosphere and on July 4 (July 5 UT) Juno is set to burn its main engine to slow down and be captured into its own orbit. If all goes well, it will be the first spacecraft to orbit the poles of Jupiter, skimming to within 5,000 kilometers of the Jovian cloud tops during the 20 month mission.
Image Credit: NASA, JPL, Juno Mission
Explanation: These three bright nebulae are often featured in telescopic tours of the constellation Sagittarius and the crowded star fields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula left of center, and colorful M20 near the bottom of the frame The third, NGC 6559, is right of M8, separated from the larger nebula by dark dust lanes. All three are stellar nurseries about five thousand light-years or so distant. The expansive M8, over a hundred light-years across, is also known as the Lagoon Nebula. M20’s popular moniker is the Trifid. In the composite image, narrowband data records ionized hydrogen, oxygen, and sulfur atoms radiating at visible wavelengths. The mapping of colors and range of brightness used to compose this cosmic still life were inspired by Van Gogh’s famous Sunflowers. Just right of the Trifid one of Messier’s open star clusters, M21, is also included on the telescopic canvas.
Image Credit & Copyright: Andrew Campbell
Sunrise Solstice over Stonehenge
Explanation: Today the Sun reaches its northernmost point in planet Earth’s sky. Called a solstice, the date traditionally marks a change of seasons — from spring to summer in Earth’s Northern Hemisphere and from fall to winter in Earth’s Southern Hemisphere. The featured image was taken during the week of the 2008 summer solstice at Stonehenge in United Kingdom, and captures a picturesque sunrise involving fog, trees, clouds, stones placed about 4,500 years ago, and a 4.5 billion year old large glowing orb. Even given the precession of the Earth’s rotational axis over the millennia, the Sun continues to rise over Stonehenge in an astronomically significant way.
Image Credit & Copyright: Max Alexander, STFC, SPL
The Horsehead Nebula in Infrared from Hubble
Explanation: While drifting through the cosmos, a magnificent interstellar dust cloud became sculpted by stellar winds and radiation to assume a recognizable shape. Fittingly named the Horsehead Nebula, it is embedded in the vast and complex Orion Nebula (M42). A potentially rewarding but difficult object to view personally with a small telescope, the above gorgeously detailed image was taken in 2013 in infrared light by the orbiting Hubble Space Telescope in honor of the 23rd anniversary of Hubble’s launch. The dark molecular cloud, roughly 1,500 light years distant, is cataloged as Barnard 33 and is seen above primarily because it is backlit by the nearby massive star Sigma Orionis. The Horsehead Nebula will slowly shift its apparent shape over the next few million years and will eventually be destroyed by the high energy starlight.
Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Valles Marineris: The Grand Canyon of Mars
Explanation: Mars will look good in Earth’s skies over the next few days — but not this good. To get a view this amazing, a spacecraft had to actually visit the red planet. Running across the image center, though, is one the largest canyons in the Solar System. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth’s Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled. Several geologic processes have been identified in the canyon. The featured mosaic was created from over 100 images of Mars taken by Viking Orbiters in the 1970s. Tomorrow, Mars and Earth will pass the closest in 11 years, resulting in the red planet being quite noticeable toward the southeast after sunset.
Image Credit: Viking Project, USGS, NASA
Rainbow Airglow over the Azores
Explanation: Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however — like an approaching storm — may cause noticeable rippling in the Earth’s atmosphere. These gravity waves are oscillations in air analogous to those created when a rock is thrown in calm water. The long-duration exposure nearly along the vertical walls of airglow likely made the undulating structure particularly visible. OK, but where do the colors originate? The deep red glow likely originates from OH molecules about 87-kilometers high, excited by ultraviolet light from the Sun. The orange and green airglow is likely caused by sodium and oxygen atoms slightly higher up. The featured image was captured during a climb up Mount Pico in the Azores of Portugal. Ground lights originate from the island of Faial in the Atlantic Ocean. A spectacular sky is visible through this banded airglow, with the central band of our Milky Way Galaxy running up the image center, and M31, the Andromeda Galaxy, visible near the top left.
Image Credit & Copyright: Miguel Claro (TWAN); Rollover Annotation: Judy Schmidt