The edges of this flame are black. No camera trickery, no special effects. What’s going on here is down to some interesting science and some excited electrons.
When you burn sodium it emits a monochromatic yellow/orange light. This happens because when sodium heats up, electrons in the atom’s orbitals become excited and they jump up to a higher energy level. When they drop back down to their original energy level they release a photon of light of a specific wavelength, which for sodium is yellow/orange.
As well emitting photons, sodium atoms also absorb photons of the same wavelength. That means if you have a light source emitting the same monochromatic light (like the sodium street lamp which we have here) the sodium atoms in the flame will absorb the light making the flame look dark.
For more flame filled visuals and a more detailed explantation of this phenomenon, check out our latest video https://www.youtube.com/watch?v=Kn2OyQh6o7U
The first image ever taken of a supermassive black hole
For the first time ever, humanity can gaze at an actual photograph of a supermassive black hole. It’s an achievement that took supercomputers, eight telescopes stationed on five continents, hundreds of researchers, and vast amounts of data to accomplish. The results from this project were announced today.
Photo credit: The Event Horizon Telescope
Today, we’re expressing gratitude for the opportunity to rove on Mars (#ThanksOppy) as we mark the completion of a successful mission that exceeded our expectations.
Our Opportunity Rover’s last communication with Earth was received on June 10, 2018, as a planet-wide dust storm blanketed the solar-powered rover’s location on the western rim of Perseverance Valley, eventually blocking out so much sunlight that the rover could no longer charge its batteries. Although the skies over Perseverance cleared, the rover did not respond to a final communication attempt on Feb. 12, 2019.
As the rover’s mission comes to an end, here are a few things to know about its opportunity to explore the Red Planet.
Opportunity launched on July 7, 2003 and landed on Mars on Jan. 24, 2004 for a planned mission of 90 Martian days, which is equivalent to 92.4 Earth days. While we did not expect the golf-cart-sized rover to survive through a Martian winter, Opportunity defied all odds as a 90-day mission turned into 15 years!
The Opportunity caught its own silhouette in this late-afternoon image taken in March 2014 by the rover’s rear hazard avoidance camera. This camera is mounted low on the rover and has a wide-angle lens.
Opportunity’s achievements, including confirmation water once flowed on Mars. Opportunity was, by far, the longest-lasting lander on Mars. Besides endurance, the six-wheeled rover set a roaming record of 28 miles.
This chart illustrates comparisons among the distances driven by various wheeled vehicles on the surface of Earth’s moon and Mars. Opportunity holds the off-Earth roving distance record after accruing 28.06 miles (45.16 kilometers) of driving on Mars.
Opportunity was created to be the mechanical equivalent of a geologist walking from place to place on the Red Planet. Its mast-mounted cameras are 5 feet high and provided 360-degree two-eyed, human-like views of the terrain. The robotic arm moved like a human arm with an elbow and wrist, and can place instruments directly up against rock and soil targets of interest. The mechanical “hand” of the arm holds a microscopic camera that served the same purpose as a geologist’s handheld magnifying lens.
After an airbag-protected landing craft settled onto the Red Planet’s surface and opened, Opportunity rolled out to take panoramic images. These images gave scientists the information they need to select promising geological targets that tell part of the story of water in Mars’ past. Since landing in 2004, Opportunity has captured more than 200,000 images. Take a look in this photo gallery.
From its perch high on a ridge, the Opportunity rover recorded this image on March 31, 2016 of a Martian dust devil twisting through the valley below. The view looks back at the rover’s tracks leading up the north-facing slope of “Knudsen Ridge,” which forms part of the southern edge of “Marathon Valley
Among the mission’s scientific goals was to search for and characterize a wide range of rocks and soils for clues to past water activity on Mars. In its time on the Red Planet, Opportunity discovered small spheres of the mineral hematite, which typically forms in water. In addition to these spheres that a scientist nicknamed “blueberries,” the rover also found signs of liquid water flowing across the surface in the past: brightly colored veins of the mineral gypsum in rocks, for instance, which indicated water flowing through underground fractures.
The small spheres on the Martian surface in this close-up image are near Fram Crater, visited by the Opportunity rover in April 2004.
For more about Opportunity’s adventures and discoveries, see: https://go.nasa.gov/ThanksOppy.
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Same but different: Spiral Galaxies NGC6935 and NGC6937 [OC] [1528x1081]
Our planet seen from Saturn, captured by the Cassini spacecraft
Image credit: NASA
M43 - Part of the same star-forming complex as the Great Orion Nebula (M42)
From an excellent post by Jason Davis
From Washington, D.C., the rings would only fill a portion of the sky, but appear striking nonetheless. Here, we see them at sunrise.
From Guatemala, only 14 degrees above the equator, the rings would begin to stretch across the horizon. Their reflected light would make the moon much brighter.
From Earth’s equator, Saturn’s rings would be viewed edge-on, appearing as a thin, bright line bisecting the sky.
At the March and September equinoxes, the Sun would be positioned directly over the rings, casting a dramatic shadow at the equator.
At midnight at the Tropic of Capricorn, which sits at 23 degrees south latitude, the Earth casts a shadow over the middle of the rings, while the outer portions remain lit.
via x