ASTRONOMY - Colors of the Moon

 2022 May 15

Colors of the Moon
Image Credit & Copyright: Marcella Giulia Pace

Explanation: What color is the Moon? It depends on the night. Outside of the Earth's atmosphere, the dark Moon, which shines by reflected sunlight, appears a magnificently brown-tinged gray. Viewed from inside the Earth's atmosphere, though, the moon can appear quite different. The featured image highlights a collection of apparent colors of the full moon documented by one astrophotographer over 10 years from different locations across Italy. A red or yellow colored moon usually indicates a moon seen near the horizon. There, some of the blue light has been scattered away by a long path through the Earth's atmosphere, sometimes laden with fine dust. A blue-colored moon is more rare and can indicate a moon seen through an atmosphere carrying larger dust particles. What created the purple moon is unclear -- it may be a combination of several effects. The last image captures the total lunar eclipse of 2018 July -- where the moon, in Earth's shadow, appeared a faint red -- due to light refracted through air around the Earth. Today there is not only another full moon but a total lunar eclipse visible to observers in North and South America -- an occurrence that may lead to some unexpected lunar colorings.

ASTRONOMY - Ice Halos by Moonlight

 2022 May 14

Ice Halos by Moonlight
Image Credit & Copyright: Alan Dyer, Amazingsky.com, TWAN

Explanation: An almost full moon on April 15 brought these luminous apparitions to a northern spring night over Alberta Canada. On that night, bright moonlight refracted and reflected by hexagonal ice crystals in high clouds created a complex of halos and arcs more commonly seen by sunlight in daytime skies. While the colors of the arcs and moondogs or paraselenae were just visible to the unaided eye, a blend of exposures ranging from 30 seconds to 1/20 second was used to render this moonlit wide-angle skyscape. The Big Dipper at the top of the frame sits just above a smiling and rainbow-hued circumzenithal arc. With Arcturus left and Regulus toward the right the Moon is centered in its often spotted 22 degree halo. May 15 will also see the bright light of a Full Moon shining in Earth's night skies. Tomorrow's Full Moon will be dimmed for a while though, as it slides through Earth's shadow in a total lunar eclipse.

ASTRONOMY - The Milky Way's Black Hole

 2022 May 13

The Milky Way's Black Hole
Image Credit: X-ray - NASA/CXC/SAO, IR - NASA/HST/STScI; Inset: Radio - Event Horizon Telescope Collaboration

Explanation: There's a black hole at the center of the Milky Way. Stars are observed to orbit a very massive and compact object there known as Sgr A* (say "sadge-ay-star"). But this just released radio image (inset) from planet Earth's Event Horizon Telescope is the first direct evidence of the Milky Way's central black hole. As predicted by Einstein's Theory of General Relativity, the four million solar mass black hole's strong gravity is bending light and creating a shadow-like dark central region surrounded by a bright ring-like structure. Supporting observations made by space-based telescopes and ground-based observatories provide a wider view of the galactic center's dynamic environment and an important context for the Event Horizon Telescope's black hole image. The main panel image shows the X-ray data from Chandra and infrared data from Hubble. While the main panel is about 7 light-years across, the Event Horizon Telescope inset image itself spans a mere 10 light-minutes at the center of our galaxy, some 27,000 light-years away.

ASTRONOMY - Young Stars of NGC 346

 2022 May 12

Young Stars of NGC 346
Image Credit: NASA, ESA - acknowledgement: Antonella Nota (ESA/STScI) et al.,

Explanation: The massive stars of NGC 346 are short lived, but very energetic. The star cluster is embedded in the largest star forming region in the Small Magellanic Cloud, some 210,000 light-years distant. Their winds and radiation sweep out an interstellar cavern in the gas and dust cloud about 200 light-years across, triggering star formation and sculpting the region's dense inner edge. Cataloged as N66, the star forming region also appears to contain a large population of infant stars. A mere 3 to 5 million years old and not yet burning hydrogen in their cores, the infant stars are strewn about the embedded star cluster. In this false-color Hubble Space Telescope image, visible and near-infrared light are seen as blue and green, while light from atomic hydrogen emission is red.

MUSIC - Mozart - The Magic Flute – Queen of the Night aria (Diana Damrau, The Royal Opera)

"Queen of the night"

ART FRACTAL - Julius Horsthuis - Fractale en 3D

ulius Horsthuis est un explorateur de l’infini. Au centre même des fractales, il nous laisse observer le monde se former, évoluer puis disparaître sous nos yeux. Expédition en terres d’inconnues, forgées par les équations.

L'artboratoire

ASTRONOMY - Gravity's Grin

 2022 May 11

Gravity's Grin
Image Credit: X-ray - NASA / CXC / J. Irwin et al. ; Optical - NASA/STScI

Explanation: Albert Einstein's general theory of relativity, published over 100 years ago, predicted the phenomenon of gravitational lensing. And that's what gives these distant galaxies such a whimsical appearance, seen through the looking glass of X-ray and optical image data from the Chandra and Hubble space telescopes. Nicknamed the Cheshire Cat galaxy group, the group's two large elliptical galaxies are suggestively framed by arcs. The arcs are optical images of distant background galaxies lensed by the foreground group's total distribution of gravitational mass. Of course, that gravitational mass is dominated by dark matter. The two large elliptical "eye" galaxies represent the brightest members of their own galaxy groups which are merging. Their relative collisional speed of nearly 1,350 kilometers/second heats gas to millions of degrees producing the X-ray glow shown in purple hues. Curiouser about galaxy group mergers? The Cheshire Cat group grins in the constellation Ursa Major, some 4.6 billion light-years away.

ASTRONOMY - Firefall by Moonlight

 2022 May 10

Firefall by Moonlight
Image Credit & Copyright: Tara Mostofi

Explanation: On certain dates in February, an elusive firefall can be spotted at sunset in Yosemite National Park, when water flows, the weather cooperates and the direction to the setting Sun is just right. Often photographed from vantage points below, at the right moment the park's seasonal Horsetail Fall is isolated in the shadows of the steep walls of El Capitan. Then, still illuminated with rays of reddened sunlight the waterfall briefly takes on a dramatic, fiery appearance. But a Horsetail firefall can be photographed by moonlight too. Even more elusive by moonlight, the firefall effect can also be seen when a bright Moon sets at the right direction along the western horizon. And skies were clear enough for this well-planned imaging of an ephemeral Horsetail firefall, lit by a bright gibbous Moon setting in the early morning hours of April 15.

ASTRONOMY - A Martian Eclipse: Phobos Crosses the Sun

2022 May 9

A Martian Eclipse: Phobos Crosses the Sun
Video Credit: NASA, JPL-Caltech, ASU MSSS, SSI

Explanation: What's that passing in front of the Sun? It looks like a moon, but it can't be Earth's Moon, because it isn't round. It's the Martian moon Phobos. The featured video was taken from the surface of Mars a month ago by the Perseverance rover. Phobos, at 11.5 kilometers across, is 150 times smaller than Luna (our moon) in diameter, but also 50 times closer to its parent planet. In fact, Phobos is so close to Mars that it is expected to break up and crash into Mars within the next 50 million years. In the near term, the low orbit of Phobos results in more rapid solar eclipses than seen from Earth. The featured video is shown in real time -- the transit really took about 40 seconds,as shown. The videographer -- the robotic rover Perseverance (Percy) -- continues to explore Jezero Crater on Mars, searching not only for clues to the watery history of the now dry world, but evidence of ancient microbial life. 

ASTRONOMY - NGC 3572 and the Southern Tadpoles

 2022 May 6

NGC 3572 and the Southern Tadpoles
Image Credit & Copyright: Carlos Taylor

Explanation: This cosmic skyscape features glowing gas and dark dust clouds along side the young stars of NGC 3572. A beautiful emission nebula and star cluster it sails far southern skies within the nautical constellation Carina. Stars from NGC 3572 are toward top center in the telescopic frame that would measure about 100 light-years across at the cluster's estimated distance of 9,000 light-years. The visible interstellar gas and dust is part of the star cluster's natal molecular cloud. Dense streamers of material within the nebula, eroded by stellar winds and radiation, clearly trail away from the energetic young stars. They are likely sites of ongoing star formation with shapes reminiscent of the Tadpoles of IC 410 better known to northern skygazers. In the coming tens to hundreds of millions of years, gas and stars in the cluster will be dispersed though, by gravitational tides and by violent supernova explosions that end the short lives of the massive cluster stars.