As regions are stressed by severe drought, communities considering how to stretch their water supply increasingly turn to the option of reclaiming wastewater. As Grady explains in this video, that idea faces both technological and psychological challenges. But neither, it turns out, is insurmountable. (Video and image credit: Practical Engineering)
Beautiful colors, subtle flows, and sudden fractals animate Thomas Blanchard’s “Sensations,” which, like his other short films, is entirely CGI-free. It’s a lovely exploration of droplets, liquid lenses, Marangoni effects, and fingering instabilities. (Video and image credit: T. Blanchard)
Since Voyager 2 visited Uranus in 1986, scientists have debated the odd ice giant’s heat balance. The other giant planets of our solar system — Jupiter, Saturn, and Neptune — all emit much more heat than they absorb from the sun, indicating that they have strong internal heat sources. Voyager 2’s measurements from Uranus indicated only weak heat emissions.
But a new study indicates that Uranus does, in fact, have an internal heat source contributing to its heat flux. The study combined observations with a global model of Uranus across the planet’s full 84-year orbit and concluded that Uranus emits 12.5% more internal heat than it absorbs from the sun. That suggests that Uranus may not be so different from its fellow giants, but the planet’s large seasonal variations and differences across hemispheres raise plenty of questions about the planet’s interior structure. (Image credit: NASA; research credit: X. Wang et al.; via Gizmodo)
These glowing wisps are the visible remains of a star that went supernova about 7,000 years ago. Today the supernova remnant is known as the Veil Nebula and is visible only through telescopes. In the image, red marks hydrogen gas and blue marks oxygen. First carried by shock waves, these remains of a former star now serve as seed material for other stars and planetary systems to form. (Image credit: A. Alharbi; via APOD)
Wind and water can form sandy ripples in a matter of minutes. Most will be erased, but some can grow to meter-scale and beyond. What distinguishes these two fates? Researchers used a laser scanner to measure early dune growth in the Namib Desert to see. They found that the underlying surface played a big role in whether sand gathered or disappeared from a given spot. Surfaces like gravel, rock, or moistened sand were better for starting a dune than loose sand was. Each of these surface types affected how much sand the wind could carry off, as well as whether grains bounced or stuck where they landed. Every trapped sand grain made the surface a little rougher, increasing the chances of trapping the next sand grain. Over time, the gathering sand forms a bump that affects the wind flow nearby, further shaping the proto-dune. As long as the wind isn’t strong enough to scour the surface clean, it will keep gathering sand as the process continues. (Image credit: M. Gheidarlou; research credit: C. Rambert et al.; via Eos)
Dissonance — the discomfort we feel when two or more musical notes feel mismatched — is more than just a subjective measure. In this video, Henry of Minute Physics delves into some of the physics involved in dissonance, first with simple sine waves and then with musical instruments. Our ears — and our brains — seem most troubled when two notes (and their overtones) are close but not quite matching in frequency. And, as Henry explains, the peaks and valleys between those agreements lead to many of the musical systems we have today. (Video and image credit: Minute Physics)
Where sea and sand meet, Gaia’s spine rises. Photographer Satheesh Nair captured this striking image in western Australia, where wind and wave action have dragged a dune into vertebrae-like cusps. Notice how the size and shape of the curves differs between the under- and above-water sections. Those differences reflect the differing forces that shape them — just water for one set, water and air for the other. (Image credit: S. Nair/IAPOTY; via Colossal)
Raging wildfires send plumes of smoke up into the atmosphere; that smoke is made up of tiny particles that can serve as seeds — nucleation sites — where water vapor can freeze and form clouds. To understand wildfire’s effect on cloud growth, researchers sampled air from the troposphere (the atmosphere’s lowest layer) both in and around wildfire smoke.
The team found that smoke increased the number of nucleating particles up to 100 times higher than the background air, but the exact make-up of the smoke varied significantly by fire. Smoke particles were mostly organic, though inorganic ones appeared as well. The temperature of a fire, as well as what materials it was burning, made a big difference; the fire where they measured the highest particle concentrations included lots of unburned plant material, thought to be carried aloft by turbulence around the fire. (Image credit: K. Barry; research credit: K. Barry et al.; via Eos)
Begun in 1238, Alhambra Palace in Grenada, Spain is a monument to Islamic architecture and clever engineering. Despite sitting far above the city, the Alhambra was fed by the river, diverted from upstream along a canal. Within the palace itself, this water was used for heated flooring, steam rooms, baths, and even a fountain that told the time. This Primal Space video breaks down how engineers pressurized the water lines, moved water into and around the palace, and how wonders like the palace’s fountains worked. As impressive as the engineering is, though, it’s worth remembering that the Alhambra’s engineers were not creating new technologies: multiple older civilizations also used aqueducts, water wheels, and siphons to similar effect. (Video and image credit: Primal Space)
Scientists are still debating exactly what shifts nature from chemical and physical reactions to living cells. But vesicles — small membrane-bound pockets of fluid carrying critical molecules — are a commonly cited ingredient. Vesicles help cluster important organic molecules together, increasing their chances of combining in the ways needed for life. Now scientists are suggesting that Titan, Saturn’s moon, could form vesicles of its own.
On Earth, molecules known as amphiphiles feature a hydrophilic (water-loving) end and a hydrophobic (water-fearing) one. When dispersed in water, amphiphiles crowd at the surface, placing their hydrophilic end in the water and their hydrophobic end outward toward the air. On Titan, the Cassini mission revealed organic nitrile molecules that behave similarly with methane rather than water.
Their two-sided structure means that these molecules — like Earth’s amphiphiles — will gather at the surface of Titan’s liquids. When methane rain falls on the Titan’s seas, the impact creates aerosol droplets that slowly settle back to the liquid surface. When that happens, the droplet’s molecular monolayer and the lake’s monolayer meet, enclosing the droplet’s contents in a double-layer of molecules that prevent contact between the droplet and the lake.
Within that newly-formed vesicle, all kinds of molecules can bump shoulders, creating new opportunities for complex chemistry. (Image credit: Titan – ESA/NASA/JPL/University of Arizona, illustration – C. Mayer and C. Nixon; research credit: C. Mayer and C. Nixon; via Gizmodo)
