http://www.acme.com/jef/apod/ The Astronomy Picture of the Day is a wonderful web site that puts up a different astronomy-related picture every day. However, the site does not have an RSS feed. This page fixes that deficiency. ]]> en-us Fri, 13 Mar 2026 13:06:30 GMT ACME Labs custom shell script jef@mail.acme.com webmaster@mail.acme.com http://www.acme.com/jef/apod/apod.GIF http://www.acme.com/jef/apod/ http://apod.nasa.gov/apod/ap260312.html Thu, 12 Mar 2026 13:06:00 GMT ]]> http://apod.nasa.gov/apod/ap260311.html Wed, 11 Mar 2026 13:06:13 GMT Is this a cosmic monster ready to devour an unsuspecting galaxy? Thankfully, that is not the case. The red “monster” shown in the featured image is Cometary Globule CG 4, 1,300 light-years away in the Constellation Puppis. CG 4 is a molecular cloud, where hydrogen becomes cold enough to form molecules that can be brought together by gravity to create stars. The shape of CG 4 resembles that of a comet, but its head is 1.5 light-year in diameter and its tail is 8 light-years long; for comparison, the distance from the Earth to the sun is only 8 light-minutes. Astronomers believe that the tail of a cometary globule could have been shaped by a nearby supernova explosion or by irradiation from hot, massive stars. Indeed, CG 4 and other nearby globules point away from the Vela Supernova Remnant, at the center of the Gum Nebula. The edge-on spiral galaxy, ESO 257-19, is more than a hundred million light-years beyond CG 4, and is completely safe from the “monster”. ]]> http://apod.nasa.gov/apod/ap260310.html Tue, 10 Mar 2026 13:06:00 GMT Are lasers from giant telescopes being used to defend the Earth? No. Lasers shot from telescopes are now commonly used to help increase the accuracy of astronomical observations. In some directions, Earth atmosphere-induced fluctuations in starlight can indicate how the air mass over a telescope is changing, but in other directions, no bright star exists. In these directions, astronomers can create an artificial star with a laser. Subsequent observations of the artificial laser guide star can reveal information so detailed about the changing blurring effects of the Earth's atmosphere that much of it can be removed by rapidly flexing a telescope's mirror. Such adaptive optics techniques allow high-resolution ground-based observations of real stars, planets, and nebulas. Pictured here, telescopes at Paranal Observatory in Chile study a colorful sky filled with green airglow and the Magellanic Clouds on the left, red airglow on the right, and the majestic central band of our Milky Way Galaxy arching across the center. ]]> http://apod.nasa.gov/apod/ap260309.html Mon, 09 Mar 2026 13:06:00 GMT What's going on inside the head of this nebula? Dubbed the Exposed Cranium Nebula for its similarity to the human brain, what created the nebula remains a mystery. One thought is that the Cranium Nebula, also known as PMR 1, is a planetary nebula surrounding a white dwarf star. In this mode, the outer atmosphere was expelled when the original Sun-like star ran out of central nuclear fuel and contracted. A competing thought is that the central star is much more massive, possibly a Wolf-Rayet star, that is ejecting gas and dust via turbulent stellar winds. Adding to the intrigue is the dark vertical central division and the thin outer gaseous shell. The featured image was taken by the Webb Space Telescope in mid- infrared light, while a second image, included as a rollover, is in near-infrared. Future observations may reveal if this brainy system will quietly just fade from view or, many years from now, suddenly erupt in a powerful supernova. ]]> http://apod.nasa.gov/apod/ap260308.html Sun, 08 Mar 2026 13:06:02 GMT Yes, but can your tree do this? Pictured is a visual coincidence between the dark branches of a nearby tree and bright glow of a distant aurora. The beauty of the aurora -- combined with how it seemed to mimic a tree right nearby -- mesmerized the photographer to such a degree that he momentarily forgot to take pictures. When viewed at the right angle, it seemed that this tree had aurora for leaves. Fortunately, before the aurora morphed into a different overall shape, he came to his senses and captured the awe-inspiring momentary coincidence. Typically triggered by solar explosions, aurora are caused by high energy electrons impacting the Earth's atmosphere around 150 kilometers up. The unusual Earth-sky collaboration was witnessed in March of 2017 in Iceland. ]]> http://apod.nasa.gov/apod/ap260307.html Sat, 07 Mar 2026 14:06:04 GMT Centered on maximum eclipse, these two total lunar eclipse sequences look almost identical. Yet the one shown on top is composed of images recorded in February 2008, while at the bottom is the recent March 2026 total eclipse of the Moon. Why are they so similar? Because these two total lunar eclipses are from the same Saros cycle. The Saros cycle was discovered historically from observations of the Moon's orbit. With a period of 18 years, 11 and 1/3 days, the cycle predicts when the Sun, Earth, and Moon all return to the same relative geometry for a lunar (or solar) eclipse. Eclipses separated by one Saros period belong to the same numbered Saros series, in this case Saros 133. So expect the next lunar eclipse in Saros 133 to be a repeat of this year's March 3 eclipse. You can watch the next Saros 133 total lunar eclipse on March 13, 2044. ]]> http://apod.nasa.gov/apod/ap260305.html Thu, 05 Mar 2026 14:07:00 GMT ]]> http://apod.nasa.gov/apod/ap260304.html Wed, 04 Mar 2026 14:06:06 GMT What’s looking back at you isn’t a cosmic eye, but Shapley 1, a beautifully symmetric planetary nebula. Shapley 1, also known as the Fine Ring Nebula or PLN 329+2.1, bejewels the southern sky constellation of the Carpenter's Square (Norma). The nebula is the result of a star near the mass of our Sun running out of fuel and shedding its outer layers. Glowing oxygen from those expelled layers makes up the circular halo. The bright central point is actually a binary: a white dwarf, the remaining stellar core after the outer layers are expelled into space, and another star, orbiting each other every 2.9 days. Shapley 1’s annular shape is due to our top-down view of the system and provides insight into the influence of central stars on planetary nebula structures. ]]> http://apod.nasa.gov/apod/ap260303.html Tue, 03 Mar 2026 14:06:02 GMT If you could fly over the North Pole of Mars, what would you see?  Images from ESA’s Mars Express mission in 2019 were compiled into the featured video which shows just such a trip. First you see below you a landscape tinted orange by rusted iron in the fine soil, with some land appearing darker due to exposed rock. Soon the northern polar cap comes into view, mostly white because of its reflective frozen water. Surrounding the polar cap is the North Polar Basin, a layered depression covered with dust and sand. The frames in the featured video were captured during northern Martian Spring when the carbon-dioxide ice is evaporating, leaving the underlying water-ice in the cap. Mars Express continues to study the Martian surface and look for clues about the Red Planet's ancient climate and potential for life. ]]> http://apod.nasa.gov/apod/ap260302.html Mon, 02 Mar 2026 14:06:00 GMT How well do you know the night sky? OK, but how well can you identify famous sky objects in a very deep image? Either way, here is a test: see if you can find some well-known night-sky icons in a deep image filled with filaments of normally faint dust and gas. This image contains the Pleiades star cluster, Barnard's Loop, Orion Nebula, Aldebaran, Betelgeuse, Witch Head Nebula, Eridanus Loop, and the California Nebula. To find their real locations, here is an annotated image version. The reason this task might be difficult is similar to the reason it is initially hard to identify familiar constellations in a very dark sky: the tapestry of our night sky has an extremely deep hidden complexity. The featured composite reveals some of this complexity in a 16 hours of sky exposure in dark skies over Granada, Spain. ]]> http://apod.nasa.gov/apod/ap260301.html Sun, 01 Mar 2026 14:06:00 GMT How does the Moon's appearance change during a total lunar eclipse? The featured time-lapse video was digitally processed to keep the Moon bright and centered during the 5-hour eclipse of 2018 January 31. At first the full moon is visible because only a full moon can undergo a lunar eclipse. Stars move by in the background because the Moon orbits the Earth during the eclipse. The circular shadow of the Earth is then seen moving across the Moon. The light blue hue of the shadow's edge is related to why Earth's sky is blue, while the deep red hue of the shadow's center is related to why the Sun appears red when near the horizon. Tomorrow night, people living in Eastern Asia, Australia, and much of North America may get to see a Total Blood Moon Lunar Eclipse. Here the term blood refers to the (likely) red color of a fully eclipsed Moon. ]]> http://apod.nasa.gov/apod/ap260228.html Sat, 28 Feb 2026 14:06:05 GMT Fans of the western sky after sunset have lately enjoyed this month's remarkable array of bright planets. Witnessed from some locations, on February 18 planet Mercury even appeared to slide behind the Moon, an event known as a lunar occultation. These two snapshots, taken in early evening skies show before and after telescopic views of the rare disappearance of innermost planet behind young Moon. The top panel finds bright Mercury just visible at the northern (right) edge of the earthshine-illuminated lunar disk. In the bottom panel the bright planet has emerged in darker skies beyond the Moon's sunlit crescent. As seen south of Sallisaw, Oklahoma, planet Earth, this lunar occultation of Mercury lasted only about 3 minutes (video). But you can still check out a parade of planets tonight. ]]> http://apod.nasa.gov/apod/ap260227.html Fri, 27 Feb 2026 14:06:00 GMT Normally faint and elusive, the Jellyfish Nebula is caught in this alluring telescopic field of view. Floating in the interstellar sea, the nebula is anchored right and left by two bright stars, Mu and Eta Geminorum, at the foot of the celestial twins. The Jellyfish Nebula itself is right of center, seen as a brighter arcing ridge of emission with dangling tentacles. In fact, this cosmic jellyfish is part of bubble-shaped supernova remnant IC 443, the expanding debris cloud from a massive star that exploded. Light from the explosion first reached planet Earth over 30,000 years ago. Like its cousin in astrophysical waters the Crab Nebula supernova remnant, the Jellyfish Nebula is known to harbor a neutron star, the ultradense remnant of the collapsed stellar core. An emission nebula cataloged as Sharpless 249 fills the field at the upper left. The Jellyfish Nebula is about 5,000 light-years away. At that distance, this image would be about 300 light-years across. ]]> http://apod.nasa.gov/apod/ap260226.html Thu, 26 Feb 2026 14:06:00 GMT What does the universe look like through infrared goggles? Our eyes can only see visible light, but astronomers want to see more. Today’s APOD shows spiral galaxy IC 5332 as seen by two NASA telescopes: Webb in mid-infrared and Hubble in ultraviolet and visible light. To toggle between the two space-based views just slide your cursor over the image (or follow this link). The Hubble image highlights the spiral arms of the galaxy separated by dark regions, whereas the Webb image reveals a finer, more tangled structure. Interstellar dust scatters and absorbs light from the stars in the galaxy, causing the dark dust lanes in the Hubble image, and then emits heat in infrared light, so dust glows in this Webb image. The Mid-InfraRed Instrument on Webb needs to operate at a chilling temperature of -266ºC (or - 447ºF), otherwise it would detect infrared radiation from the telescope itself. Combining these observations, astronomers connect the “small scale” of gas and stars to the truly large scale of galactic structure and evolution. ]]> http://apod.nasa.gov/apod/ap260225.html Wed, 25 Feb 2026 14:06:06 GMT Ever wonder what it would look like to crack open the Sun? The Egg Nebula, a dying Sun-like star, can unscramble this question. Pictured is a combination of several visible and infrared images of the nebula (also known as RAFGL 2688 or CRL 2688) taken with the Hubble Space Telescope. The star has shed its outer layers, and a bright, hot core (or "yolk") now illuminates the milky "egg white" shells of gas and dust surrounding the center. The central lobes and rings are structures of gas and dust recently ejected into space, with the dust being dense enough to block our view of the stellar core. Light beams emanate from that blocked core, escaping through holes carved in the older ejected material by newer, faster jets expelled from the star’s poles. Astronomers are still trying to figure out what causes the disks, lobes, and jets during this short (only a few thousand years!) phase of the star’s evolution, making this an egg-cellent image to study! ]]> http://apod.nasa.gov/apod/ap260224.html Tue, 24 Feb 2026 14:06:00 GMT Look up this week and see a whole bunch of planets. Just after sunset, looking west (mostly), planets Mercury, Venus, Saturn, and Jupiter will all be visible to the unaided eye simultaneously. If you have a telescope, planets Uranus and Neptune can also be seen. In order up from the horizon, the lineup this week will be Venus (the brightest), Mercury, Saturn, Neptune, Uranus, and Jupiter (second brightest). It doesn't matter where on Earth you live because this early evening planet parade will be visible through clear skies all around the globe. The planets will appear to be nearly in a line because they all orbit the Sun in nearly the same plane: the ecliptic. The featured image shows a similar planet parade that occurred in 2022, captured over the Sydney Opera House in southern Australia. Although visible all week, the planets will be most easily seen together this weekend. ]]> http://apod.nasa.gov/apod/ap260223.html Mon, 23 Feb 2026 14:06:00 GMT Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as large and clear as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen with the unaided eye even from the depths of a light-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident. The featured 18-hour exposure, taken from Bory Tucholskie, Poland covers a sky area several times the size of the full moon. Also known as the Seven Sisters and M45, the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus). A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six of the sister stars visible to the unaided eye. The actual number of Pleiades stars visible, however, may be more or less than seven, depending on the darkness of the surrounding sky and the clarity of the observer's eyesight. ]]> http://apod.nasa.gov/apod/ap260222.html Sun, 22 Feb 2026 14:06:00 GMT What if you saw your shadow on Mars and it wasn't human? Then you might be the Opportunity rover exploring Mars. Opportunity explored the Red Planet from 2004 to 2018, finding evidence of ancient water, and sending breathtaking images across the inner Solar System. Pictured here in 2004, Opportunity looks opposite the Sun into Endurance Crater and sees its own shadow. Two wheels are visible on the lower left and right, while the floor and walls of the unusual crater are visible in the background. Caught in a dust storm in 2018, Opportunity stopped responding, and NASA stopped trying to contact it in 2019 and declared the ground-breaking mission, originally planned for only 92 days, complete. ]]> http://apod.nasa.gov/apod/ap260221.html Sat, 21 Feb 2026 14:06:00 GMT Only two days after the February New Moon's annular eclipse of the Sun, a slender lunar crescent poses above the western horizon after sunset in this wintry twilight skyscape. Its nightside faintly illuminated by earthshine, the young Moon is joined by three bright planets in the mostly clear, early evening skies above the village of Kirazli, Turkiye. Inner planet Venus appears closest to the horizon. Near the beginning of its 2026 performance as planet Earth's evening star, brilliant Venus is seen through the warm sunset glare near picture center. Straight above Venus, innermost planet Mercury is easy to spot as it stands remarkably high above the horizon even as the twilight sky is growing dark. Outer planet Saturn, most distant of the naked-eye planets, is found just left of the Moon's sunlit crescent. ]]> http://apod.nasa.gov/apod/ap260220.html Fri, 20 Feb 2026 14:06:00 GMT "A ghost in the Milky Way…” says Christian Bertincourt, the astrophotographer behind this striking image of Barnard 93 (B93). The 93rd entry in Barnard’s Catalogue of Dark Nebulae, B93 lies within the Small Sagittarius Star Cloud (Messier 24), where its darkness stands in stark contrast to bright stars and gas in the background. In some ways, B93 is really like a ghost, because it contains gas and dust that was dispersed by the deaths of stars, like supernovas. B93 appears as a dark void not because it is empty, but because its dust blocks the light emitted by more distant stars and glowing gas. Like other dark nebulas, some gas from B93, if dense and massive enough, will eventually gravitationally condense to form new stars. If so, then once these stars ignite, B93 will transform from a dark ghost into a brilliant cradle of newborn stars. ]]>