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Explanation: 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...

Explanation: 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...

Explanation: 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...

For a few years now, it has been blindingly obvious that New York had over-promised and over-committed on impossible “climate” goals that could not be achieved. In various posts I have referred to this as an approaching “cliff,” or perhaps as the “green energy wall.” It has been entertaining to ponder what the final disaster might look like. This week has had a lot of developments. Most interesting is the growing split among the governing Democrats between, on the one hand, those who see disaster coming and are looking for some kind of graceful exit and, on the other hand,...

Explanation: 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...

Explanation: 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...

Explanation: Do young stars blow bubbles? The larger view shows a stellar field observed with the Cerro Tololo Inter-American Observatory in Chile, and the inset highlights HD 61005, a star like our Sun, only 120 light-years away. Much younger than the Sun, at just about 100 million years old, it blows a fast and dense stellar wind that pushes out the cooler dust and gas that surrounds it, forming a bubble called an astrosphere. The star-blown bubble was detected with the Chandra X-ray Observatory, and it has a diameter roughly 200 times the Earth-Sun distance. Our Sun has a bubble...

Explanation: Earlier this week, Earth’s shadow swept across the full Moon in the year’s only total lunar eclipse. This stunning sequence combines images showing the Moon’s path across the night sky. Each lunar image captures our planet’s shadow gradually engulfing the Moon, culminating in its red glow. Sunlight scatters and refracts as it passes through Earth’s atmosphere toward the Moon. Shorter wavelength light (blue and green) scatters more efficiently, leaving red, orange, and yellow hues to paint the lunar surface. Tsé Bit'a'í (”rock with wings”, also known as Shiprock), located in Navajo Nation, provides a powerful volcanic foreground central to...

Explanation: 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,...

Explanation: 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...

Explanation: 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...

Explanation: 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...

Explanation: 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....

Explanation: 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...

Explanation: 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,...

Explanation: 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...

Explanation: 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...

Explanation: 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...

Explanation: 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...

Explanation: 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...