The Green Flash
"Given a clear path to the horizon — such as over the ocean — this means that there’s a slight region of space just above the reddened Sun where only the shorter wavelength light is visible!
And when that happens, in addition to the normal color gradient that comes with a sunset, you can also get a small, separate region above the disk of the Sun that appears yellow, green, or even blue! (And much fainter than the rest of the Sun!)”
During sunset, the Sun appears to redden, dim, and eventually sink below the horizon. Every once in a while, a rare phenomenon emerges along with it: a green flash, where a greenish-colored beam of light appears just over the Sun. What causes it? One of the most beautiful natural phenomena our planet has to offer, explained in glorious detail.
This infrared image shows a kilometer-high volcanic vortex swirling over the Bardarbunga eruption. The bright red at the bottom is lava escaping the fissure, whereas the yellow and white regions show rising hot gases. Although the vortex looks similar to a tornado, it is actually more like a dust devil or a so-called fire tornado. All three of these vortices are driven by a heat source near the ground that generates buoyant updrafts of air. As the hot gases rise, cooler air flows in to replace them. Any small vorticity in that ambient air gets amplified as it’s drawn to the center, the same way an ice skater spins faster when she pulls her arms in. With the right conditions, a vortex can form. Unlike a harmless dust devil, though, this vortex is likely filled with sulphur dioxide and volcanic ash and would pose a serious hazard to aviation. (Image credit: Nicarnica Aviation; source video; via io9)
By Dwayne Godwin and Jorge Cham
Scientists have created the first map of a colossal supercluster of galaxies known as Laniakea, the home of Earth’s Milky Way galaxy and many others. This computer simulation, a still from a Nature journal video, depicts the giant supercluster, with the Milky Way’s location shown as a red dot.
The scientists responsible for the new 3D map suggest that the newfound Laniakea supercluster of galaxies may even be part of a still-larger structure they have not fully defined yet.
“We live in something called ‘the cosmic web,’ where galaxies are connected in tendrils separated by giant voids,” said lead study author Brent Tully, an astronomer at the University of Hawaii at Honolulu.
Galaxies are not spread randomly throughout the universe. Instead, they clump in groups, such as the one Earth is in, the Local Group, which contains dozens of galaxies. In turn, these groups are part of massive clusters made up of hundreds of galaxies, all interconnected in a web of filaments in which galaxies are strung like pearls. The colossal structures known as superclusters form at the intersections of filaments.
The giant structures making up the universe often have unclear boundaries. To better define these structures, astronomers examined Cosmicflows-2, the largest-ever catalog of the motions of galaxies, reasoning that each galaxy belongs to the structure whose gravity is making it flow toward.
"We have a new way of defining large-scale structures from the velocities of galaxies rather than just looking at their distribution in the sky," Tully said.
The new 3D map developed by Tully and colleagues shows that the Milky Way galaxy resides in the outskirts of the Laniakea Supercluster, which is about 520 million light-years wide. The supercluster is made up of about 100,000 galaxies with a total mass about 100 million billion times that of the sun.
The name Laniakea was suggested by Nawa’a Napoleon, who teaches Hawaiian language at Kapiolani Community College in Hawaii. The name is meant to honor Polynesian navigators who used their knowledge of the heavens to make long voyages across the immensity of the Pacific Ocean.
"We live in the Local Group, which is part of the Local Sheet next to the Local Void — we wanted to come up with something a little more exciting than ‘Local,’" Tully told Space.com.
This supercluster also includes the Virgo cluster and Norma-Hydra-Centaurus, otherwise known as the Great Attractor. These new findings help clear up the role of the Great Attractor, which is a problem that has kept astronomers busy for 30 years. Within the Laniakea Supercluster, the motions of galaxies are directed inward, as water flows in descending paths down a valley, and the Great Attractor acts like a large flat-bottomed gravitational valley with a sphere of attraction that extends across the Laniakea Supercluster.
Tully noted Laniakea could be part of an even larger structure.
"We probably need to measure to another factor of three in distance to explain our local motion," Tully said. "We might find that we have to come up with another name for something larger than we’re a part of — we’re entertaining that as a real possibility."
The scientists detailed their findings in the Sept. 4 issue of the journal Nature.
I love this.
Seeing a supernovae within hours of the explosion
For the first time ever, scientists have gathered direct evidence of a rare Wolf-Rayet star being linked to a specific type of stellar explosion known as a Type IIb supernova. Peter Nugent of the Lawrence Berkeley National Laboratory says they caught this star – a whopping 360 million light years away – just a few hours after it exploded.
occupancy: Solar corona, photographed by SOHO, 15th June 2014.
40 images, inverted, over 11 hours. 10 images per gif.
Image credit: NASA/SOHO. Animation: AgeOfDestruction.
It was only a matter of time.
A prototype laser turret attached to a test aircraft.
Prepare yourself for a future filled with real-life pew pew! The Defense Advanced Research Projects Agency is working with Lockheed Martin to test “a new beam control turret… to give 360-degree coverage…
The otherworldly beauty of microscopic organisms
Marine diatoms are one of the smallest creatures on Earth. UK-based biologist Klaus Kemp and filmographer Matthew Killip teamed up to showcase these minuscule organisms’ diverse beauty.
Diatoms are single-celled organisms found in oceans all over the world. There are estimated to be 100,000 species of these micron-sized creatures in existence, and they play a crucial role as one of the main food sources for marine organisms, including fish, molluscs and tunicates, such as sea squirts.
Once you get them under the microscope, the diatoms will reveal the incredible glass shells that contain their tiny bodies. During the Victorian era - the second half of the 19th century - scientists would pop them under their microscopes and lay them out in complex and beautiful arrangements, and UK-based biologist Klaus Kemp is one of the last remaining scientists on Earth to keep the practice alive.
Filmographer Matthew Killip made a documentary about Kemp, as the master of diatom art, and these stunning images were the result. Killip explains how the film came to be over at Neatorama:
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