Walter, a young African penguin at the New York Aquarium, loves soap bubbles. In fairness to Walter, so do most people I’ve met. There’s just something that feels a bit magical about these ephemeral rainbow spheres that pop at a (dry) touch.
NASA’s X-59 aircraft is intended to demonstrate supersonic flight without the boom. Although it’s broken into supersonic speeds, we haven’t yet heard its “sonic thump” because, so far, it’s been accompanied by conventional supersonic aircraft, which are louder.
The idea behind the long, skinny X-59 is to create weaker, widely-spaced shocks along the aircraft body. Weaker shocks are easier for atmospheric effects to damp out before they reach the ground, and spacing them out makes it harder for them to “pile up” at the nose and tail to create the strong double shocks that merge into a sonic boom.
Schlieren image of a model X-59 tested at supersonic conditions in a wind tunnel. The model is mounted upside-down. The three dark diagonal lines are shock waves originating from the wind tunnel and can be ignored. The fainter lines coming off parts of the aircraft model are the plane’s shock waves.
NASA is preparing to test the X-59’s in-flight shocks soon, including with in-air schlieren photography like they’ve done in the past for other aircraft. But we’ve already have a glimpse of what to expect, thanks to wind tunnel testing, shown above. Ignore the three dark diagonal lines in the middle of the image (those are from the wind tunnel, not the model aircraft), and focus instead on the thin bright lines coming off the plane. Those are some impressively subtle shock waves!
In cold weather, a new geological feature has shown up at Utah’s Great Salt Lake in the last decade. These salty mirabilite mounds form terraced crystals that resemble Yellowstone’s Mammoth Hot Springs.
Diagram showing how a salt-laden spring pushing upward through the mirabilite layer can then form mounds at the surface when the dissolved mirabilite recrystallizes after the water evaporates.
Mirabilite is hydrated sodium sulfate (as opposed to the sodium chloride of table salt). The structures form when upwelling spring water partially dissolves the layer of mirabilite found beneath the lake bed. That sulfate-laden water rises to the surface, where it freezes into the crystals seen here.
A timelapse showing the formation of mirabilite mounds.
When temperatures rise above freezing, the water in the mirabilite evaporates, leaving behind white, powdery thenardite. (Video credit: Great Salt Lake Institute; image credit: Utah Geological Survey)
In the early twentieth century, Los Angeles had capital and political willpower, but not water. So it built an engineering marvel, the LA Aquaduct, to guide water from the Sierra Nevadas down to the growing city. Grady gets into the literal (and figurative) ups and downs of the project in this Practical Engineering video.
Although the engineering prowess of the aquaduct system is impressive, as Grady points out, the LA Aquaduct’s story is much more complicated than the engineering needed to move water between two points. It’s a story where greed, corruption, politics, cultural impact, environment effects, and climate change all intersect. (Video and image credit: Practical Engineering)
Keeping the water in a reservoir is an obvious challenge for any dam. But for Iraq’s Mosul Dam, it’s especially challenging because the dam was built on a foundation of gypsum, a highly water-soluble mineral. Since it was built, Mosul Dam’s water has been eating away at the underlying bedrock, making sinkholes, forcing gaps, and generally working its way out. That, obviously, creates a huge risk for dam failure and massive downstream flooding.
To get the dam stabilized–at least to a point where Iraqi engineers could keep up with filling the holes as they form–took a massive international engineering project, carried out in the shadow of armed conflict. (Video and image credit: Practical Engineering)
In the Southern Ocean, obstacles are sparse. But the ice-cloaked volcano of Peter I Island is tall enough at over 1600 meters to disrupt the wind. At steady wind speeds between about 18 to 54 kilometers per hour, flowing past the island creates vortices that shed from one side and then the other. The result is a von Karman vortex street like the one seen here, flowing toward the upper right.
The overlaid ripple structures in the cloud layer are reminiscent of gravity waves. Perhaps, the wind’s passage made some lee waves that the vortices distorted? (Image credit: M. Garrison; via NASA Earth Observatory)
Off the coast of Alaska, March 19th, 2026 featured a trio of fascinating clouds. Southwest of Anchorage, a cyclonic polar low twisted up from cold polar air centered over warmer waters. This particular storm boasted tropical-storm-force winds and thunderstorms in its center.
Further west, long cloud streets formed parallel to the wind as cold dry air picked up moisture from warmer polar waters. And, finally, in the bottom left of the image, alternating vortices swirl in the wake of a rocky island, forming a beautiful von Karman vortex street. (Image credit: M. Garrison/NASA Earth Observatory)
Engineering failures always leave us with lessons learned. The failure of Teton Dam in 1976 triggered an overhaul in how we manage dam construction and regulation. As Grady describes in this Practical Engineering video, the earthen dam was built with fundamental flaws that allowed water to carve pathways beneath and through the sediment meant to hold it. Although the dam cost $100 million to build, its failure cost the federal government over three times that in claims. (Video and image credit: Practical Engineering)
In early February 2026, cold weather swept into southern Florida. The cold fronts churned up sediment and cooled shallow waters, making them denser than the warmer waters of the open ocean. That caused the cooled water to sink off the continental shelf, carrying bright sediment with it. The satellite images of swirling sediment remind me of Impressionist paintings. (Image credit: M. Garrison; via NASA Earth Observatory)
Breaking a jet of liquid into droplets lies at the heart of many industrial processes: spray painting, fuel injection, and asthma inhalers, to name a few. Here, researchers are looking at a different method of breaking up a liquid jet: shooting a shock wave along its length. The poster shows five different snapshots of the jet’s response. There are, variously, mists of fine droplets, wavy distortions of the jet, sheets, ligaments, and droplets of many sizes. (Image credit: S. Rao et al.)
Research poster showing black and white images of liquid jets after a shock wave passed along the length of each jet.
