Tuesday, May 31, 2016
The SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) is the world's most powerful X-ray laser. The two-mile-long linear accelerator is used to produce ultrafast pulses of light (30 femtoseconds) in order to take stop-motion pictures of atoms and molecules in motion. The laser's wavelength (0.151nm) is comparable to that of an atom, which provides extremely high resolution imaging capabilities. Here, a pulse of the X-ray laser can be seen vaporizing 40µm droplets of water. Because of the speed of the interaction, imagery is captured in stop-motion over many repeated experiments and combined to produce a video. A secondary, time-delayed pulsed laser is used to illuminated the scene following the primary X-ray laser interaction.
Source: https://youtu.be/v5bH01qNN0Y PhysOrg
Article: http://phys.org/news/2016-05-movies-droplets-blown-x-ray-laser.html Nature
Physics publication: http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3779.html
Mars will look good in Earth's skies over the next few days -- but not this good. To get a view this amazing, a spacecraft had to actually visit the red planet. Running across the image center, though, is one the largest canyons in the Solar System. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep.
By comparison, the Earth's Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled. Several geologic processes have been identified in the canyon. The featured mosaic was created from over 100 images of Mars taken by Viking Orbiters in the 1970s. Tomorrow, Mars and Earth will pass the closest in 11 years, resulting in the red planet being quite noticeable toward the southeast after sunset.
Image & Info via APODhttp://apod.nasa.gov/apod/astropix.html
Image Credit: Viking Project, USGS, NASA
Monday, May 30, 2016
Why is this aurora strikingly pink? Although much is known about the physical mechanisms that create auroras, accurately predicting the occurrence and colors of auroras remains a topic of investigation. Typically, it is known, the lowest auroras appear green. These occur at about 100 kilometers high and involve atmospheric oxygen atoms excited by fast moving plasma from space.
The next highest auroras -- at about 200 kilometers up -- appear red, and are also emitted by resettling atmospheric oxygen. Some of the highest auroras visible -- as high as 500 kilometers up -- appear blue, and are caused by sunlight-scattering nitrogen ions.
When looking from the ground through different layers of distant auroras, their colors can combine to produce unique and spectacular hues, in this case rare pink hues seen below.
Image & info via APOD
Image Credit & Copyright: Brad Goldpaint (Goldpaint Photography)
Sitting at Saturn’s south pole is a vortex of monstrous proportions. The dark ‘eye’ of this feature is some 8000 km across, or about two thirds the diameter of Earth.
is 10 times more detailed than any previous picture of the polar vortex and shows a level of detail inside the eye that was not previously observable. Earlier images showed towering clouds around the edge of this vortex, but inside the air was thought to be mostly transparent. Here, however, a multitude of features is revealed.
Clouds are produced by convection – warm, rising gases in the atmosphere of Saturn. As they reach higher, and therefore colder, layers of the atmosphere, the gases condense and appear as clouds. At the 10 o’clock position, a stream of upwelling gas has created its own smaller vortex inside the larger one.
This view is an adjusted composite of two frames taken by the
Cassini spacecraft on 14 July 2008. Cassini actually captured the scene from an oblique angle, some 56º below the plane of Saturn’s rings – a far cry from the view directly over the south pole. The orbiter was about 392 000 km from the planet at the time, yet Cassini’s camera still provided a resolution of 2 km per pixel.
Towering eye-walls of cloud are a distinguishing feature of hurricanes on Earth. Like earthly hurricanes, the eye of this storm is composed of warmer gas than the surroundings. However, whereas hurricanes are powered by warm water and move across the surface of our planet, this vortex has no liquid ocean at its base and remains fixed to Saturn’s south pole.
Round, swirling vortices are part of the general circulation in the atmospheres of all four giant, outer planets, and Cassini has spied many mobile ones rolling through Saturn’s clouds at other latitudes. While vortices are often informally referred to as storms, scientists generally reserve that term for bright, short-lived bursts of convection that punch though the clouds, often accompanied by lightning.
In addition to being a thing of beauty, the vortex provides astronomers with a way to look deep into the planet’s atmosphere.Image & info via ESA
Credits: NASA/JPL/Space Science Institutehttp://www.esa.int/Highlights/Week_In_Images_09_13_May_2016