ASTRONOMY - Red Spider Planetary Nebula from Webb

 2026 February 3

Red Spider Planetary Nebula from Webb
Image Credit: ESA/Webb, NASA & CSA, J. H. Kastner (RIT)

Explanation: Oh what a tangled web a planetary nebula can weave. The Red Spider Planetary Nebula shows the complex structure that can result when a normal star ejects its outer gases and becomes a white dwarf star. Officially tagged NGC 6537, this two-lobed symmetric planetary nebula houses one of the hottest white dwarfs ever observed, probably as part of a binary star system. Internal winds flowing out from the central stars, have been measured in excess of 1,000 kilometers per second. These winds expand the nebula, flow along the nebula's walls, and cause waves of hot gas and dust to collide. Atoms caught in these colliding shocks radiate light shown in the featured false-color infrared picture by the James Webb Space Telescope. The Red Spider Nebula lies toward the constellation of the Archer (Sagittarius). Its distance is not well known but has been estimated by some to be about 4,000 light-years.

SANTé/MEDECINE - Tout savoir sur le coeur - 11 - Opérations du cœur

À gauche, la valve mitrale a été remplacée par une valve artificielle. Cette opération est souvent nécessaire en cas de malformation de la valve auriculo-ventriculaire ou suite à une insuffisance valvulaire (défaut de fermeture de la valve). À droite, un pontage coronarien permet de contourner une artère coronaire bouchée et d'apporter du sang riche en oxygène au muscle cardiaque, grâce à un vaisseau greffé. Ce vaisseau greffé provient souvent de la jambe.

© 2018 Patrick Lynch

ASTRONOMY -The Bay of Rainbows

 2026 February 12

The Bay of Rainbows
Image Credit & Copyright: Olaf Filzinger

Explanation: Dark, smooth regions that cover the Moon's familiar face are called by Latin names for oceans and seas. That naming convention is historical, though it may seem a little ironic to denizens of the space age who recognize the Moon as a mostly dry and airless world, and the smooth, dark areas as lava-flooded impact basins. For example, this telescopic lunar vista, looks over the expanse of the northwestern Mare Imbrium, or Sea of Rains and into the Sinus Iridum, the Bay of Rainbows. Ringed by the Jura Mountains (montes), the bay is about 250 kilometers across. Seen after local sunrise, the mountains form part of the Sinus Iridum impact crater wall. Their rugged sunlit arc is bounded at the top by Cape (promontorium) Laplace reaching nearly 3,000 meters above the bay's surface. At the bottom of the arc is Cape Heraclides, depicted by Giovanni Cassini in his 1679 telescope-based drawings mapping the moon, as a moon maiden seen in profile with long, flowing hair.

SANTé/MEDECINE - Tout savoir sur le coeur humain - 10 - Infarctus dans le ventricule gauche

Si une artère coronaire est obstruée, l'irrigation du myocarde en sang diminue localement. Les cellules musculaires manquent d'oxygène et sont affaiblies. Si la situation se prolonge, elle risque de provoquer un infarctus du myocarde, ou crise cardiaque. Certaines régions du muscle cardiaque sont nécrosées : elles sont colorées en sombre en bas de l'illustration. Plus les lésions sont étendues, plus les chances de survie sont minces.

© Patrick J. Lynch, CC by-sa 2.5

ASTRONOMY - A Year of Sunspots

 2026 February 11

A Year of Sunspots
Image Credit: NASA, SDO; Processing & Copyright: Şenol Şanli & Uğur İkizler; Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)

Explanation: How many sunspots can you see? The central image shows the many sunspots that occurred in 2025, month by month around the circle, and all together in the grand central image. Each sunspot is magnetically cooled and so appears dark -- and can last from days to months. Although the featured images originated from NASA's Solar Dynamics Observatory, sunspots can be easily seen with a small telescope or binoculars equipped with a solar filter. Very large sunspot groups like recent AR 4366 can even be seen with eclipse glasses. Sunspots are still counted by eye, but the total number is not considered exact because they frequently change and break up. Last year, 2025, coincided with a solar maximum, the period of most intense magnetic activity during its 11-year solar cycle. Our Sun remains unpredictable in many ways, including when it ejects solar flares that will impact the Earth, and how active the next solar cycle will be.

ASTRONOMY - In Green Company: Aurora over Norway

 2026 February 10

In Green Company: Aurora over Norway
Image Credit & Copyright: Max Rive

Explanation: Raise your arms if you see an aurora. With those instructions, two nights went by with, well, clouds -- mostly. On the third night of returning to same peaks, though, the sky not only cleared up but lit up with a spectacular auroral display. Arms went high in the air, patience and experience paid off, and the creative featured image was captured as a composite from three separate exposures. The setting is a summit of the Austnesfjorden (a fjord) close to the town of Svolvear on the Lofoten islands in northern Norway. The year was 2014. This year, our Sun is just passing solar maximum, the peak in its 11-year surface activity cycle. As expected, some spectacular auroras have recently resulted.

ASTRONOMY - Miranda Revisited

 2026 February 9

Miranda Revisited
Image Credit: NASA, JPL, Voyager 2; Processing & License: Flickr: zelario12; Text: Keighley Rockcliffe (NASA GSFC, UMBC CSST, CRESST II)

Explanation: What is Miranda really like? Visually, old images from NASA's Voyager 2 have been recently combined and remastered to result in the featured image of Uranus's 500-kilometer-wide moon. In the late 1980s, Voyager 2 flew by Uranus, coming close to the cratered, fractured, and unusually grooved moon -- named after a character from Shakespeare’s The Tempest. Scientifically, planetary scientists are using old data and clear images to theorize anew about what shaped Miranda's severe surface features. A leading hypothesis is that Miranda, beneath its icy surface, may have once hosted an expansive liquid water ocean which may be slowly freezing. Thanks to the legacy of Voyager 2, Miranda has joined the ranks of Europa, Titan, and other icy moons in the search for water, and, possibly, microbial life, in our Solar System.

SANTé/MEDECINE - Tout savoir sur le coeur humain - 9 - Pseudo-anévrisme du ventricule gauche

Un pseudo-anévrisme, aussi appelé faux anévrisme, est une poche de sang qui se forme près du myocarde. Contrairement aux vrais anévrismes, il ne possède pas d'éléments du myocarde, mais risque de se rompre. Les pseudo-anévrismes du ventricule gauche sont rares, mais il s'agit souvent d'une complication d'un infarctus du myocarde. Ils peuvent aussi survenir après une opération cardiaque ou une infection.

© Patrick J. Lynch, CC by-sa 2.5

ASTRONOMY - Active Sunspot Region 4366 Crosses the Sun

 2026 February 8

Active Sunspot Region 4366 Crosses the Sun
Image Credit & Copyright: Daniel Korona

Explanation: An unusually active sunspot region is now crossing the Sun. The region, labelled AR 4366, is much larger than the Earth and has produced several powerful solar flares over the past ten days. In the featured image, the region is marked by large and dark sunspots toward the upper right of the Sun's disk. The image captured the Sun over a hill in Zacatecas, Mexico, 5 days ago. AR 4366 has become a candidate for the most active solar region in this entire 11-year solar cycle. Active solar regions are frequently associated with increased auroral activity on the Earth. Now reaching the edge, AR 4366 will begin facing away from the Earth during the coming week. It is not known, though, if the active region will survive long enough to reappear in about two weeks' time, as the Sun rotates.

ASTRONOMY - Crescent Enceladus

 2026 February 7

Crescent Enceladus
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Peering from the shadows, the Saturn-facing hemisphere of tantalizing inner moon Enceladus poses in this Cassini spacecraft image. North is up in the dramatic scene captured during November 2016 as Cassini's camera was pointed in a nearly sunward direction about 130,000 kilometers from the moon's bright crescent. In fact, the distant world reflects over 90 percent of the sunlight it receives, giving its surface about the same reflectivity as fresh snow. A mere 500 kilometers in diameter, Enceladus is a surprisingly active moon. Data and images collected during Cassini's flybys have revealed water vapor and ice grains spewing from south polar geysers and evidence of an ocean of liquid water hidden beneath the moon's icy crust.

SANTé/MEDECINE - Tout savoir sur le coeur humain - 8 - Anatomie du cœur droit

Le cœur droit reçoit le sang pauvre en oxygène provenant des veines caves qui entre dans l'oreillette droite (ici sur la gauche de l'illustration). Le sang est mis sous pressiondans le ventricule droit et est expulsé du cœur par les artères pulmonaire, pour rejoindre les poumons. Voyez la valve sigmoïde du tronc pulmonaire, formée de trois valvules en « croissants de lune».

© Patrick J. Lynch, CC by-sa 2.5

ASTRONOMY - Supernova Remnant Cassiopeia A

 2026 February 6

Supernova Remnant Cassiopeia A
Image Credit: NASA, ESA, CSA, STScI; D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)

Explanation: Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After only a few million years for the most massive stars, the enriched material is blasted back into interstellar space where star formation can begin anew. The expanding debris cloud known as Cassiopeia A is an example of this final phase of the stellar life cycle. Light from the supernova explosion that created this remnant would have been first seen in planet Earth's sky about 350 years ago, although it took that light 11,000 years to reach us. This sharp NIRCam image from the James Webb Space Telescope shows the still-hot filaments and knots in the supernova remnant. The whitish, smoke-like outer shell of the expanding blast wave is about 20 light-years across. A series of light echoes from the massive star's cataclysmic explosion are also identified in Webb's detailed images of the surrounding interstellar medium.

SANTé/MEDECINE - Tout savoir sur le coeur humain - 7 - La valve tricuspide

La valve auriculo-ventriculaire droite, aussi appelée valve tricuspide, est une valve cardiaque composée de trois cuspides, qui sont des lames d'endocarde. Cette valve est attachée par des cordons de collagène blanc, qui relient les cuspides à la paroi du ventricule. Quand le cœur est relâché, la valve est ouverte, puis elle se ferme quand les ventricules se contractent.

© Patrick J. Lynch, CC by-sa 2.5

ASTRONOMY - Artemis I: Flight Day 13

 2026 January 31

Artemis I: Flight Day 13
Image Credit: NASA, Artemis I

Explanation: On flight day 13 (November 28, 2022) of the Artemis 1 mission, the Orion spacecraft reached its maximum distance from Earth. At over 430,000 kilometers from Earth, its distant retrograde orbit also puts Orion nearly 70,000 kilometers from the Moon. In the same field of view in this video frame from flight day 13, planet and large natural satellite even appear about the same apparent size from the spacecraft's perspective. On flight day 26 (December 11, 2022), the uncrewed spacecraft splashed down on its home world concluding the historic Artemis I mission. The Artemis II mission, carrying 4 astronauts around the moon and back again, will launch no earlier than February 8.

ASTRONOMY - Spiral Galaxy NGC 1512: Wide Field

 2026 February 4

Spiral Galaxy NGC 1512: Wide Field
Image Credit & Copyright: Daniel Stern

Explanation: Most galaxies don't have any rings -- why does this galaxy have three? To begin, a ring that's near NGC 1512's center -- and so hard to see here -- is the nuclear ring which glows brightly with recently formed stars. Next out is a ring of stars and dust appearing both red and blue, called, counter-intuitively, the inner ring. This inner ring connects ends of a diffuse central bar of stars that runs horizontally across the galaxy. Farthest out in this wide field image is a ragged structure that might be considered an outer ring. This outer ring appears spiral-like and is dotted with clusters of bright blue stars. All these ring structures are thought to be affected by NGC 1512's own gravitational asymmetries in a drawn-out process called secular evolution. The featured image was captured last month from a telescope at Deep Sky Chile in Chile.

SANTé/MEDECINE - Tout savoir sur le coeur humain - 6 - Échocardiographie d’un cœur normal

Au centre, observez la valve de l'aorte qui empêche le sang de refluer dans le ventricule ; cette valve dite sigmoïde est composée de trois valvules en forme de pochettes. Le ventricule gauche est reconnaissable par sa paroi musculaire plus épaisse.

© Patrick J. Lynch, CC by-sa 2.5

ASTRONOMY - Orion: The Running Man Nebula

2026 February 2

Orion: The Running Man Nebula
Image Credit & Copyright: Robert G. Lyons (Robservatory)

Explanation: What part of Orion is this? Just north of the famous Orion Nebula is a picturesque star forming region in Orion's Sword that contains a lot of intricate dust -- some of which appears blue because it reflects the light of bright embedded stars. The region's popular name is the Running Man Nebula because, looked at from the right, part of the brown dust appears to be running legs. Cataloged as Sharpless 279, the reflection nebula is not only part of the constellation of Orion, but part of the greater Orion molecular cloud complex. Light from the Running Man's bright stars, including 42 Orionis, the bright star closest to the featured image center, is slowly destroying and reshaping the surrounding dust, which will likely be completely gone in about 10 million years. The nebula spans about 15 light years and lies about 1,500 light years away. 

ASTRONOMY - Galle: Happy Face Crater on Mars

2026 February 1

Galle: Happy Face Crater on Mars
Image Credit: NASA, MGS, MSSS

Explanation: Mars has put on a happy face. The Martian crater Galle is famous because it has internal markings that make it look like a face that is both smiling and winking. These markings were originally discovered in the 1970s in pictures taken by the Viking Orbiter. The Mars Global Surveyor (MGS) spacecraft that orbited Mars from 1996 to 2006 captured the featured picture. Happy Face Crater and its iconic features were formed by chance billions of years ago when a city-sized asteroid slammed into the Martian surface. All rocky planets and moons in our Solar System show impact craters, with the highest number of craters found on Earth's Moon and the planet Mercury. Earth and Venus would show the most, though, were it not for weather and erosion. 

SANTé/MEDECINE - Tout savoir sur le coeur humain - 5 - Vue gauche du cœur : les structures internes

Dans cette illustration, le cœur gauche est coloré en rouge et le droit en bleu, en référence aux sangs qui transitent dans leurs cavités : le cœur gauche envoie du sang riche en oxygène dans l'organisme, tandis que le cœur droit reçoit le sang pauvre en oxygène. Trois valves cardiaques sont représentées : les valves auriculo-ventriculaires et la valve du tronc pulmonaire.

© Patrick J. Lynch, CC by-sa 2.5

ASTRONOMY - NGC 1333: Stellar Nursery in Perseus

 2026 January 30

NGC 1333: Stellar Nursery in Perseus
Image Credit & Copyright: Robert Eder

Explanation: NGC 1333 is seen in visible light as a reflection nebula, dominated by bluish hues characteristic of starlight reflected by interstellar dust. A mere 1,000 light-years distant toward the heroic constellation Perseus, it lies at the edge of a large, star-forming molecular cloud. This telescopic close-up spans over two full moons on the sky or just over 15 light-years at the estimated distance of NGC 1333. It shows details of the dusty region along with telltale hints of contrasty red emission from Herbig-Haro objects, jets and shocked glowing gas emanating from recently formed stars. In fact, NGC 1333 contains hundreds of stars less than a million years old, most still hidden from optical telescopes by the pervasive stardust. The chaotic environment may be similar to one in which our own Sun formed over 4.5 billion years ago.