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NASA Astronomy Picture of the Day:

The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the orange emission nebula at the far right of the featured picture. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will surely alter its appearance. The emission nebula's orange color is caused by electrons recombining with protons to form hydrogen atoms. Toward the lower left of the image is the Flame Nebula, an orange-tinged nebula that also contains intricate filaments of dark dust.

Photo by Daniel Stern

Coral (Favia favus), Ras Muhammad National Park, Red Sea, Egypt. This species of stony corals is massive and forms thickly encrusting dome-shaped colonial corals. There is a great diversity of form even among the same species. The corallites project slightly above the surface of the coral and each has its own wall. The septa and costae linked to the corallite wall are well developed and covered by fine teeth. The polyps only extend and feed during the night. Each one has a small number of tapering tentacles which often have a darker coloured tip; these are called stinger tentacles, or sweeper tentacles. They use these to sweep the water to see if any other coral is in its area; if so, then they begin to sting the other coral. This is commonly known as coral war. Each coral is trying to make sure it has enough room around it so it can continue to grow and have more surface area for its offspring.

Diego Delso, CC BY-SA 4.0, via Wikimedia Commons. View source.

NASA Astronomy Picture of the Day:

Its surface is the most densely cratered in the Solar System -- but what's inside? Jupiter's moon Callisto is a battered ball of dirty ice that is larger than the planet Mercury. It was visited by NASA's Galileo spacecraft in the 1990s and 2000s, but the recently reprocessed featured image is from a flyby of NASA's Voyager 2 in 1979. The moon would appear darker if it weren't for the tapestry of light-colored fractured surface ice created by eons of impacts. The interior of Callisto is potentially even more interesting because therein might lie an internal layer of liquid water. This potential underground sea is a candidate to harbor life -- similar with sister moons Europa and Ganymede. Callisto is slightly larger than Luna, Earth's Moon, but because of its high ice content is slightly less massive. ESA's JUICE and NASA's Europa Clipper missions are now headed out to Jupiter to better investigate its largest moons.

A real-life "Rosie the Riveter" operating a hand drill at a Vultee factory in Nashville, working on an A-31 Vengeance dive bomber. Today is Labor Day in the United States.

Alfred T. Palmer, Public domain, via Wikimedia Commons. View source.

W. H. H. MacKellar is the most likely originator of this expression based on the 1939 citation in “The Rotarian”. Gil Stern popularized a version beginning in 1967. Other attributions have been made but there is not strong support for them. Read more

No man is an island,
Entire of itself.
Each is a piece of the continent,
A part of the main.
If a clod be washed away by the sea,
Europe is the less.
As well as if a promontory were.
As well as if a manor of thine own
Or of thine friend's were.
Each man's death diminishes me,
For I am involved in mankind.
Therefore, send not to know
For whom the bell tolls,
It tolls for thee.

John Donne, (1572 - 1631), was a leading English poet, scholar, soldier and secretary of the Metaphysical school and dean of St. Paul’s Cathedral, London. Donne is often considered the greatest love poet in the English language. He is also noted for his religious verse and treatises and for his sermons, which rank among the best of the 17th century. Donne was born of Roman Catholic parents when practice of that religion was illegal in England. His poetical works include sonnets, love poems, religious poems, Latin translations, epigrams, elegies, songs and satires. He is also known for his sermons.

Source: Devotions Upon Emergent Occasions, Meditation XVII

NASA Astronomy Picture of the Day:

What created this unusual planetary nebula? Dubbed the Pillow Nebula and the Flying Carpet Nebula, NGC 7027 is one of the smallest, brightest, and most unusually shaped planetary nebulas known. Given its expansion rate, NGC 7027 first started expanding, as visible from Earth, about 600 years ago. For much of its history, the planetary nebula has been expelling shells, as seen in blue in the featured image by the Hubble Space Telescope. In modern times, though, for reasons unknown, it began ejecting gas and dust (seen in brown) in specific directions that created a new pattern that seems to have four corners. What lies at the nebula's center is unknown, with one hypothesis holding it to be a close binary star system where one star sheds gas onto an erratic disk orbiting the other star. NGC 7027, about 3,000 light years away, was first discovered in 1878 and can be seen with a standard backyard telescope toward the constellation of the Swan (Cygnus).

Formula 1, Dutch Grand Prix 2024: Carlos Sainz jr (ESP, Scuderia Ferrari). Today is this year's Grand Prix.

Steffen Prößdorf, CC BY-SA 4.0, via Wikimedia Commons. View source.