2013 May 13

Partial Solar Eclipse with Airplane
* Image Credit & Copyright: Phillip Calais

Explanation:
It was just eight minutes after sunrise, last week, and already there were four things in front of the Sun. The largest and most notable was Earth's Moon, obscuring a big chunk of the Sun's lower limb as it moved across the solar disk, as viewed from Fremantle, Australia. This was expected as the image was taken during a partial solar eclipse -- an eclipse that left sunlight streaming around all sides of the Moon from some locations. Next, a band of clouds divided the Sun horizontally while showing interesting internal structure vertically. The third intervening body might be considered to be the Earth's atmosphere, as it dimmed the Sun from its higher altitude brightness while density fluctuations caused the Sun's edges to appear to shimmer. Although closest to the photographer, the least expected solar occulter was an airplane. Quite possibly, passengers on both sides of that airplane were contemplating the unusual view only visible out the eastern-facing windows.

https://apod.nasa.gov/apod/ap130513.html

2023 October 8

Plane, Clouds, Moon, Spots, Sun
* Image Credit & Copyright: Doyle and Shannon Slifer

Explanation:
What's that in front of the Sun? The closest object is an airplane, visible just below the Sun's center and caught purely by chance. Next out are numerous clouds in Earth's atmosphere, creating a series of darkened horizontal streaks. Farther out is Earth's Moon, seen as the large dark circular bite on the upper right. Just above the airplane and just below the Sun's surface are sunspots. The main sunspot group captured here, AR 2192, was in 2014 one of the largest ever recorded and had been crackling and bursting with flares since it came around the edge of the Sun a week before. This show of solar silhouettes was unfortunately short-lived. Within a few seconds the plane flew away. Within a few minutes the clouds drifted off. Within a few hours the partial solar eclipse of the Sun by the Moon was over. Fortunately, when it comes to the Sun, even unexpected alignments are surprisingly frequent. Perhaps one will be imaged this Saturday when a new partial solar eclipse will be visible from much of North and South America.

https://apod.nasa.gov/apod/ap231008.html

2020 June 24

Inverted City Beneath Clouds
* Image Credit & Copyright: Mark Hersch

Explanation:
How could that city be upside-down? The city, Chicago, was actually perfectly right-side up. The long shadows it projected onto nearby Lake Michigan near sunset, however, when seen in reflection, made the buildings appear inverted. This fascinating, puzzling, yet beautiful image was captured by a photographer in 2014 on an airplane on approach to Chicago's O'Hare International Airport. The Sun can be seen both above and below the cloud deck, with the latter reflected in the calm lake. As a bonus, if you look really closely -- and this is quite a challenge -- you can find another airplane in the image, likely also on approach to the same airport.

https://apod.nasa.gov/apod/ap200624.html

2025 August 10

Snapshot of alien captured on surveillance camera!
* Image Credit: Leading Safety Officer Rainer Zufall
https://www.rainerzufall.com/termine/

Explanation:
Since yesterday, Saturday, we have certainty that they live among us ALIENS! This unique photo of a surveillance camera at an emergency exit of the Goddart Space Flight Center is the unequivocal evidence. Both management and staff of the facility are now puzzling over what the obviously intended attempt to enter the facility was supposed to achieve, perhaps the extraterrestrial spaceman wanted to borrow a cup of fuel or had the crew run out of milk? Astronomers and astrobiologists suspect the origin of the nocturnal visitor in the area of NGC 6334, also known as "The Cat's Paw Nebula"
https://defcon.social/@grobi/114890269801928650

Dawn of the Crab
* Image and Text Credit: Bradley E. Schaefer
https://www.lsu.edu/physics/people/faculty/schaefer.php

Explanation:
One of the all-time historic skyscapes occured in July 1054, when the Crab Supernova blazed into the dawn sky. Chinese court astrologers first saw the Guest Star on the morning of 4 July 1054 next to the star Tianguan (now cataloged as Zeta Tauri). The supernova peaked in late July 1054 a bit brighter than Venus, and was visible in the daytime for 23 days. The Guest Star was so bright that every culture around the world inevitably discovered the supernova independently, although only nine reports survive, including those from China, Japan, and Constantinople. This iPhone picture is from Signal Hill near Tucson on the morning of 26 July 2025, faithfully re-creates the year 1054 Dawn of the Crab, showing the sky as seen by Hohokam peoples. The planet Venus, as a stand-in for the supernova, is close to the position of what is now the Crab Nebula supernova remnant. Step outside on a summer dawn with bright Venus, and ask yourself "What would you have thought in ancient times when suddenly seeing the Dawn of the Crab?"

+ Crab Nebula:
https://en.wikipedia.org/wiki/SN_1054
https://apod.nasa.gov/apod/ap011227.html
+ Zeta Tauri:
https://www.star-facts.com/tianguan-zeta-tauri/
http://stars.astro.illinois.edu/sow/zetatau.html
+ Astrophysics:
https://ui.adsabs.harvard.edu/abs/2003LNP...598..195P/abstract

+ History:
https://ui.adsabs.harvard.edu/abs/2003LNP...598....7G/abstract
https://www.kyohaku.go.jp/eng/learn/home/dictio/shoseki/sadaie/
https://www.nytimes.com/1978/07/18/archives/old-text-is-linked-to-1054-supernova-scientific-journal-tells-of.html
+ Hystorical Chinese Astrology:
https://www.lehigh.edu/~dwp0/Assets/images/astroorigins.pdf
+ Cultural:
https://www.britannica.com/topic/Hohokam-culture
https://www.nps.gov/articles/000/signal-hill-petroglyphs.htm

+ Education:
https://spaceplace.nasa.gov/supernova/en/

https://apod.nasa.gov/apod/ap250808.html

"Why not take to the air right away?"

2020 February 9

To Fly Free in Space
* Image Credit: NASA, STS-41B
https://www.nasa.gov/
https://www.nasa.gov/mission/sts-41b/

Explanation:
What would it be like to fly free in space? At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was living the dream -- floating farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an "untethered space walk" during Space Shuttle mission 41-B in 1984. The MMU worked by shooting jets of nitrogen and was used to help deploy and retrieve satellites. With a mass over 140 kilograms, an MMU is heavy on Earth, but, like everything, is weightless when drifting in orbit. The MMU was later replaced with the SAFER backpack propulsion unit.
https://en.wikipedia.org/wiki/Manned_Maneuvering_Unit

https://apod.nasa.gov/apod/ap200209.html

Tardigrades in space

From Wikipedia

The use of tardigrades in space, first proposed in 1964 because of their extreme tolerance to radiation, began in 2007 with the FOTON-M3 mission in low Earth orbit, where they were exposed to space's vacuum for 10 days, and reanimated, just by rehydration, back on Earth. In 2011, tardigrades were on board the International Space Station on STS-134. In 2019, a capsule containing tardigrades was on board the Israeli lunar lander Beresheet which crashed on the Moon.

Tardigrades are small arthropods able to tolerate extreme environments. Many live in tufts of moss, such as on rooftops, where they get repeatedly dried out and rewetted. Others live in the Arctic or atop mountains, where they are exposed to cold. When dried, they go into a cryptobiotic 'tun' state in which metabolism is suspended. They have been described as the toughest animals on Earth.
Their DNA is protected from damage, such as by radiation, by Dsup proteins.

In 1964, R.M. May and colleagues proposed that the tardigrade Macrobiotus areolatus would be a suitable model organism for space experiments because of its exceptional radiation tolerance.

In 2001, R. Bertolani and colleagues proposed tardigrades as a model for a study of animal survival in space. As terrestrial experiments on tardigrades proceeded, knowledge of their survival abilities grew, enabling K.I. Jönsson in 2007, and then other researchers such as Daiki Horikawa in 2008 and Roberto Guidetti in 2012, to present evidence that they would resist desiccation, radiation, heat, and cold, suiting them for astrobiological studies.

In 2008, F. Ono and colleagues suggested that tardigrades might be able to survive a journey through space on a meteorite, enabling panspermia, the transfer of life from one planet to another. [...]
More in ALT-Text
https://en.wikipedia.org/wiki/Tardigrades_in_space

By contributors to Wikimedia projects

Tardigrades,

known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär 'little water bear'. In 1776, the Italian biologist Lazzaro Spallanzani named them Tardigrada, which means 'slow walkers'.

They live in diverse regions of Earth's biosphere – mountaintops, the deep sea, tropical rainforests, and the Antarctic. Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions – such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation – that would quickly kill most other forms of life. Tardigrades have survived exposure to outer space.

There are about 1,500 known species in the phylum Tardigrada, a part of the superphylum Ecdysozoa. The earliest known fossil is from the Cambrian, some 500 million years ago. They lack several of the Hox genes found in arthropods, and the middle region of the body corresponding to an arthropod's thorax and abdomen. Instead, most of their body is homologous to an arthropod's head.

Tardigrades are usually about 0.5 mm (0.02 in) long when fully grown. They are short and plump, with four pairs of legs, each ending in claws (usually four to eight) or sticky pads. Tardigrades are prevalent in mosses and lichens and can readily be collected and viewed under a low-power microscope, making them accessible to students and amateur scientists. Their clumsy crawling and their well-known ability to survive life-stopping events have brought them into science fiction and popular culture including items of clothing, statues, soft toys and crochet patterns. [...]

https://en.wikipedia.org/wiki/Tardigrade

2023 May 21

Tardigrade in Moss
* Image Credit & Copyright: Nicole Ottawa & Oliver Meckes / Eye of Science / Science Source Images
https://www.sciencesource.com/

Explanation:
Is this an alien? Probably not, but of all the animals on Earth, the tardigrade might be the candidate. That's because tardigrades are known to be able to go for decades without food or water, to survive temperatures from near absolute zero to well above the boiling point of water, to survive pressures from near zero to well above that on ocean floors, and to survive direct exposure to dangerous radiations. The far-ranging survivability of these extremophiles was tested in 2011 outside an orbiting space shuttle. Tardigrades are so durable partly because they can repair their own DNA and reduce their body water content to a few percent. Some of these miniature water-bears almost became extraterrestrials in 2011 when they were launched toward to the Martian moon Phobos, and again in 2021 when they were launched toward Earth's own moon, but the former launch failed, and the latter landing crashed. Tardigrades are more common than humans across most of the Earth. Pictured here in a color-enhanced electron micrograph, a millimeter-long tardigrade crawls on moss.

https://apod.nasa.gov/apod/ap230521.html

"Before going to bed, we dedicate ourselves once again to the works of Judy W. Ross. Because in an anniversary year, all those involved and supporters should receive the recognition they deserve."

2003 October 17

Astronomy Quilt of the Week
* Credit & Copyright: Judy W. Ross, Point Roberts, WA

Explanation:
Demonstrating her mastery of a traditional astronomical imaging technique quilter and astronomy enthusiast Judy Ross has produced this spectacular composition of "Astronomy Quilt Piece of the Week". Her year-long effort resulted in an arrangement for a six by seven foot quilt consisting of 52 individual pieces (11 inches by 8 inches), one for each week, which she reports were inspired by her steady diet of APOD's daily offerings. Some of the pieces are based on actual pictures, such as the Hubble Space Telescope's view of planet forming AB Aurigae or Bill Keel's image of the nearby Pinwheel Galaxy. Others, with titles like the Blue Carpet Nebula and Duck Contemplates Black Hole, are from her own creative imaginings.

"After a somewhat clumsy and obviously drunk young man has just vomited on the carpet in the entrance area, in order to enable him to recover quickly, sufficient fresh air was provided and we now make a pleasant fire in the fireplace."

2021 March 3

Stars over an Erupting Volcano
* Image Credit & Copyright: Giuseppe Vella
https://www.instagram.com/Peppe.vella_photography/

Explanation:
Mt. Etna has been erupting for hundreds of thousands of years. Located in Sicily, Italy, the volcano produces lava fountains over one kilometer high. Mt. Etna is not only one of the most active volcanoes on Earth, it is one of the largest, measuring over 50 kilometers at its base and rising nearly 3 kilometers high. Pictured erupting last month, a lava plume shoots upwards, while hot lava flows down the volcano's exterior. Likely satellite trails appear above, while ancient stars dot the sky far in the distance. This volcanic eruption was so strong that nearby airports were closed to keep planes from flying through the dangerous plume. The image foreground and background were captured consecutively by the same camera and from the same location.

https://apod.nasa.gov/apod/ap210303.html

"How about a little manual work for a change to really come down from the stress of the day? Let's be inspired by the quilting of Judy W. Ross and make ourselves comfortable with a cup of tea."

2004 November 25

What the Hubble Saw
* Credit & Copyright: Judy W. Ross, Point Roberts, WA

Explanation:
In this striking 41 inch by 38 inch quilt, astronomy enthusiast Judy Ross has interpreted some of the Hubble Space Telescope's best galactic and extragalactic vistas. Featured in past APODs, clockwise from the lower right are; the Red Rectangle Nebula, NGC 2392, the Sleeping Beauty Galaxy, V838 Monocerotis - the Milky Way's most mysterious star, and supernova remnant N49 - the cosmic debris from an exploded star. Of course, quilts have been used historically to represent astronomical concepts. And while inspired by the images of the cosmos that she incorporates into her quilts, Ross reports that she is still a little daunted by the intricacies of the Cat's Eye Nebula revealed by the Hubble's sharp vision.
https://quiltindex.org/

https://apod.nasa.gov/apod/ap041125.html

"To all conspiracy theoists and myth hunters among us: This is NOT proof that Supersonic aircraft are not descended from mammals!"

2007 August 19
(first released 2001 February 21)

A Sonic Boom
* Credit: Ensign John Gay, USS Constellation, US Navy
https://www.navy.mil/
https://en.wikipedia.org/wiki/USS_Constellation_%28CV-64%29

Explanation:
Is this what a sonic boom looks like? When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane, and so accumulate in a cone behind the plane. When this shock wave passes, a listener hears all at once the sound emitted over a longer period: a sonic boom. As a plane accelerates to just break the sound barrier, however, an unusual cloud might form. The origin of this cloud is still debated. A leading theory is that a drop in air pressure at the plane described by the Prandtl-Glauert Singularity occurs so that moist air condenses there to form water droplets. Above, an F/A-18 Hornet was photographed just as it broke the sound barrier. Large meteors and the space shuttle frequently produce audible sonic booms before they are slowed below sound speed by the Earth's atmosphere.
https://www.pbs.org/wgbh/nova/barrier/boom/concept3.html
https://www.phy.ntnu.edu.tw/~hwang/Doppler/Doppler.html
https://www.phy.ntnu.edu.tw/~hwang/airplane/airplane.html
https://www.pbs.org/wgbh/nova/barrier/boom/concept2.html

https://apod.nasa.gov/apod/ap070819.html

2015 December 24

Star Colors and Pinyon Pine
* Image Credit & Copyright: Stan Honda
http://www.stanhonda.com/

Explanation:
Beautiful, luminous decorations on this pinyon pine tree are actually bright stars in the constellation Scorpius and the faint glow of the central Milky Way. Captured in June from the north rim of the Grand Canyon of planet Earth, the shallow, close focus image has rendered pine needles on the tree branch sharp, but blurred the distant stars, their light smeared into remarkably colorful disks. Of course, temperature determines the color of a star. Most of the out-of-focus bright stars of Scorpius show a predominately blue hue, their surface temperatures much hotter than the Sun's. Cooler and larger than the Sun, and noticably redder on the scene, is giant star Antares at the heart of the scorpion. In focused, telescopic views the whitish disk at the upper right would be immediately recognizable though, reflecting the Sun's light as ringed gas giant Saturn.
https://apod.nasa.gov/apod/ap110211.html

https://apod.nasa.gov/apod/ap151224.html

"This type of cloud certainly has nothing natural or close to nature about it, but despite symmetry rather the aesthetics of destruction. Nevertheless spectacular .."

2006 August 22

A Smoke Angel from Airplane Flares
* Credit: Russell E. Cooley IV, USAF
https://www.af.mil/

Explanation:
What type of cloud is that? It is not a naturally occurring one. Looking perhaps a bit like a gigantic owl monster, the cloud pictured above resulted from a series of flares released by an air force jet over the Atlantic Ocean in May. The jet that released the flares, a C-17 Globemaster III, is seen on the right. The flares release smoke and the resulting pattern is sometimes known as a smoke angel. The circular eyes of the above smoke angel are caused by air spiraling off the plane's wings and are known as wingtip vortices.

https://apod.nasa.gov/apod/ap060822.html

@futurebird

"Thank you for accompanying me through space and time!
We are 100 now .. ok with me 101 that's worth a little celebration, isn't it? "

Comet Between Fireworks and Lightning
* Image Credit & Copyright: Antti Kemppainen

Explanation:
Sometimes the sky itself is the best show in town. In January 2007, people from Perth, Australia gathered on a local beach to watch a sky light up with delights near and far. Nearby, fireworks exploded as part of Australia Day celebrations. On the far right, lightning from a thunderstorm flashed in the distance. Near the image center, though, seen through clouds, was the most unusual sight of all: Comet McNaught. The photogenic comet was so bright that it even remained visible though the din of Earthly flashes. Comet McNaught has now returned to the outer Solar System and is now only visible with a large telescope. The featured image is actually a three photograph panorama digitally processed to reduce red reflections from the exploding firework.

https://apod.nasa.gov/apod/ap131110.html

2020 April 5

Color the Universe!
* Image Credit: Unknown

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.
https://en.wikipedia.org/wiki/Flammarion_engraving
https://www.historyofinformation.com/detail.php?id=3329
https://www.youtube.com/watch?v=6zp60ODhbb4
https://gallica.bnf.fr/ark:/12148/bpt6k408619m/f4.image
https://books.google.com/books?id=ScDVAAAAMAAJ&pg=PA163
https://en.wikipedia.org/wiki/Camille_Flammarion
https://apod.nasa.gov/apod/ap010101.html

https://www.thecolor.com/Category/Coloring/Planets.aspx
https://www.huffpost.com/entry/coloring-for-stress_n_5975832

For Your Contribution:
http://asterisk.apod.com/discuss_apod.php?date=200405

https://apod.nasa.gov/apod/ap200405.html

Eclipses in mythology and culture

from Contributors to Wikimedia projects

Eclipses of the Sun and of the Moon have been described by nearly every culture. In cultures without an astronomical explanation, eclipses were often attributed to supernatural causes or regarded as bad omens.
---
Religious and cultural practices

While solar and lunar eclipses are today understood astronomically as one celestial body shadowing another, their appearance from Earth does not intuitively belie a similar cause for each.
Mark Littmann, Fred Espenak, and Ken Willcox classified solar eclipse mythologies into four distinct genres:

+ A celestial being (usually a monster) attempts to destroy the Sun.
+ The Sun fights with its lover the Moon.
+ The Sun and Moon make love and discreetly hide themselves in darkness.
+ The Sun god grows angry, sad, sick, or neglectful.
---
Abrahamic religions

In the Talmud, solar eclipses are described as ill omens and several events in the Hebrew Bible are said to have occurred during eclipses. Judaism at large has been accepting of the modern astronomical explanation of eclipses and today many rabbis consider eclipses to be reminders of divinity and a time for prayer and introspection.
___
The periodicity of lunar eclipses been deduced by Neo-Babylonian astronomers in the sixth century BCE and the periodicity of solar eclipses was deduced in first century BCE by Greek astronomers, who developed the Antikythera mechanism and had understood the Sun, Moon, and Earth to be spherical celestial bodies since Aristotle. The astronomical understanding of eclipses was thus well understood in the Ancient Near East in which Christianity developed.
___
The New Testament describes the sky as darkening for hours during the crucifixion of Jesus. As the event's lengthy duration and occurrence on the day of a ...
Read more
https://en.wikipedia.org/wiki/Eclipses_in_mythology_and_culture#

2020 June 15

A Ring of Fire Sunrise Solar Eclipse
* Video Credit: Colin Legg & Geoff Sims
https://www.facebook.com/ColinLeggPhotography
https://www.facebook.com/BeyondBeneath
* Music: Peter Nanasi
https://www.peternanasi.com/about

Explanation:
What's rising above the horizon behind those clouds? It's the Sun. Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun. At times, it would be hard for the uninformed to understand what was happening. In an annular eclipse, the Moon is too far from the Earth to block the entire Sun, and at most leaves a ring of fire where sunlight pours out around every edge of the Moon. The featured time-lapse video also recorded the eclipse through the high refraction of the Earth's atmosphere just above the horizon, making the unusual rising Sun and Moon appear also flattened. As the video continues on, the Sun continues to rise, and the Sun and Moon begin to separate. This weekend, a new annular solar eclipse will occur, visible from central Africa, the Arabian Peninsula, and a narrow band across Asia, with much of Earth's Eastern hemisphere being able to see a partial solar eclipse.

https://apod.nasa.gov/apod/ap200615.html

** Note by grobi:
"To upload this video, I converted it and compressed it to a smaller file-size under #linux with the free software ffmpeg and the corresponding command:

'ffmpeg -i video_in.mkv -vcodec libx265 -crf 28 video_out.mp4'

Maybe you would like to post a corresponding video on a scientifically related topic, but it is perhaps too big? Then try ffmpeg."

"Welcome back to the
Space Culture Club
(Feel free to contribute, rather as a reply than using the hashtag)
https://defcon.social/@grobi/114663418339078163 "

2023 September 17

Moon Mountains Magnified during Ring of Fire Eclipse
* Credit & Copyright: Wang Letian (Eyes at Night)
http://www.luckwlt.com/About%20Me.html

Explanation:
What are those dark streaks in this composite image of a solar eclipse? They are reversed shadows of mountains at the edge of the Moon. The center image, captured from Xiamen, China, has the Moon's center directly in front of the Sun's center. The Moon, though, was too far from the Earth to completely block the entire Sun. Light that streamed around the edges of the Moon is called a ring of fire. Images at each end of the sequence show sunlight that streamed through lunar valleys. As the Moon moved further in front of the Sun, left to right, only the higher peaks on the Moon's perimeter could block sunlight. Therefore, thehttps://defcon.social/@grobi/114663418339078163 dark streaks are projected, distorted, reversed, and magnified shadows of mountains at the Moon's edge. Bright areas are called Baily's Beads. Only people in a narrow swath across Earth's Eastern Hemisphere were able to view this full annular solar eclipse in 2020. Next month, though, a narrow swath crossing both North and South America will be exposed to the next annular solar eclipse. And next April, a total solar eclipse will be visible across North America.

https://apod.nasa.gov/apod/ap230917.html