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2019 April 9 Moon Occults Saturn Image Credit & Copyright: Cory Schmitz Explanation: Sometimes Saturn disappears. It doesn’t really go away, though, it just disappears from view when our Moon moves in front. Such a Saturnian eclipse was visible along a small swath of Earth — from Brazil to Sri Lanka — near the end of last month. The featured color image is a digital fusion of the clearest images captured by successive videos of the event taken in red, green, and blue, and taken separately for Saturn and the comparative bright Moon. The exposures were taken from South Africa just before occultation — and also just before sunrise. When Saturn re-appeared on the other side of the Moon almost two hours later, the Sun…

2019 April 8 AZURE Vapor Tracers over Norway Image Credit & Copyright: Yang Sutie Explanation: What’s happening in the sky? The atmosphere over northern Norway appeared quite strange for about 30 minutes last Friday when colorful clouds, dots, and plumes suddenly appeared. The colors were actually created by the NASA-funded Auroral Zone Upwelling Rocket Experiment (AZURE) which dispersed gas tracers to probe winds in Earth’s upper atmosphere. AZURE’s tracers originated from two short-lived sounding rockets launched from the Andøya Space Center in Norway. The harmless gases, trimethylaluminum and a barium/strontium mixture, were released into the ionosphere at altitudes of 115 and 250 km. The vapor trails were observed dispersing from several ground stations. Mapping how AZURE’s vapors dispersed should increase humanity’s understanding of how the…

2019 April 7 A Scorpius Sky Spectacular Image Credit & Copyright: Stéphane Guisard, TWAN 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 featured 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…

2019 April 6 ISS from Wallasey Image Credit & Copyright: Richard Addis Explanation: After sunset on March 28, the International Space Station climbed above the western horizon, as seen from Wallasey, England at the mouth of the River Mersey. Still glinting in the sunlight some 400 kilometers above planet Earth, the fast moving ISS was followed by hand with a small backyard telescope and high frame rate digital camera. A total of 2500 frames were recorded during the 7 minute long visible ISS passage and 100 of them captured images of the space station. These are the four best frames showing remarkable details of the ISS in low Earth orbit. Near the peak of its track, about 60 degrees above the horizon, the ISS was…

2019 April 5 Pan-STARRS Across the Sky Image Credit: R. White (STScI) and the PS1 Science Consortium Explanation: This astronomical sky spanning view is a mosaic from the Pan-STARRS observatory. The images were recorded with its 1.8 meter telescope at the summit of Haleakala on planet Earth’s island of Maui. In fact, Earth’s north celestial pole is centered in this across-the-sky projection. A declination of -30 degrees, the southern horizon limit as seen from the Hawaiian Valley Isle, defines the circular outer edge. Crowded starfields and cosmic dust clouds along the plane of our Milky Way galaxy stretch across the scene with the bright bulge of the galactic center at the bottom. Compiled over four years, the image data represent the second edition of data…

2019 April 4 Messier 2 Image Credit: ESA/Hubble & NASA, G. Piotto et al. Explanation: After the Crab Nebula, M1, this giant star cluster is the second entry in 18th century astronomer Charles Messier’s famous list of things with are not comets. M2 is one of the largest globular star clusters now known to roam the halo of our Milky Way galaxy. Though Messier originally described it a nebula without stars, this stunning Hubble image resolves stars across the central 40 light-years of M2. Its population of stars numbers close to 150,000, concentrated within a total diameter of around 175 light-years. About 55,000 light-years distant toward the constellation Aquarius, this ancient denizen of the Milky Way, also known as NGC 7089, is 13 billion years…

2019 April 3 Wisps Surrounding the Horsehead Nebula Image Credit & Copyright: Mario Zauner Explanation: The famous Horsehead Nebula in Orion is not alone. A deep exposure shows that the dark familiar shaped indentation, visible just below center, is part of a vast complex of absorbing dust and glowing gas. To bring out details of the Horsehead’s pasture, an amateur astronomer used a backyard telescope in Austria to accumulate and artistically combine 7.5 hours of images in the light of Hydrogen (red), Oxygen (green), and Sulfur (blue). The resulting spectacular picture details an intricate tapestry of gaseous wisps and dust-laden filaments that were created and sculpted over eons by stellar winds and ancient supernovas. The Flame Nebula is visible just to the left of the…

2019 April 2 Space Station Silhouette on the Moon Image Credit & Copyright: Eric Holland Explanation: What’s that unusual spot on the Moon? It’s the International Space Station. Using precise timing, the Earth-orbiting space platform was photographed in front of a partially lit gibbous Moon last month. The featured image was taken from Palo Alto, California, USA with an exposure time of only 1/667 of a second. In contrast, the duration of the transit of the ISS across the entire Moon was about half a second. A close inspection of this unusually crisp ISS silhouette will reveal the outlines of numerous solar panels and trusses. The bright crater Tycho is visible on the lower left, as well as comparatively rough, light colored terrain known as…

2019 April 1 Astronaut Kicks Lunar Field Goal Image Credit: NASA, Apollo 15 Team Explanation: Score three points for NASA. With time running out late in Apollo 15’s mission to the Moon in 1971, Astronaut David Scott prepared to split the uprights and bring about yet another dramatic end-of-the-mission victory for NASA. Scott used a special lunar football designed for the rugged games held on the Moon. R1-D1, a predecessor to R2-D2, cheered from the sideline. Happy April Fools’ Day from the folks at APOD. In reality, Astronaut Scott placed a drill that measured how temperature changed with lunar depth. The foreground device actually detected high-energy particles that escaped from the Sun.

2019 March 31 Markarian’s Chain of Galaxies Image Credit & Copyright: Sergio Kaminsky Explanation: Across the heart of the Virgo Cluster of Galaxies lies a striking string of galaxies known as Markarian’s Chain. The chain, pictured here, is highlighted on the right with two large but featureless lenticular galaxies, M84 and M86. Prominent to their lower left is a pair of interacting galaxies known as The Eyes. The home Virgo Cluster is the nearest cluster of galaxies, contains over 2000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies surrounding our Milky Way Galaxy. The center of the Virgo Cluster is located about 70 million light years away toward the constellation of Virgo. At least seven galaxies in…