mercredi 11 février 2015

Giant Filament Seen on the Sun












NASA - Solar Dynamics Observatory (SDO) patch.

February 11, 2015


A dark, snaking line across the lower half of the sun in this Feb. 10, 2015 image from NASA's Solar Dynamics Observatory (SDO) shows a filament of solar material hovering above the sun's surface. SDO shows colder material as dark and hotter material as light, so the line is, in fact, an enormous swatch of colder material hovering in the sun's atmosphere, the corona. Stretched out, that line – or solar filament as scientists call it – would be more than 533,000 miles long. That is longer than 67 Earths lined up in a row. Filaments can float sedately for days before disappearing. Sometimes they also erupt out into space, releasing solar material in a shower that either rains back down or escapes out into space, becoming a moving cloud known as a coronal mass ejection, or CME. SDO captured images of the filament in numerous wavelengths, each of which helps highlight material of different temperatures on the sun. By looking at such features in different wavelengths and temperatures, scientists learn more about what causes these structures, as well as what catalyzes their occasional eruptions.

Launched on Feb. 11, 2010 aboard a ULA Atlas V rocket from Cape Canaveral Air Force Station, Fla., NASA's Solar Dynamics Observatory is designed to study the causes of solar variability and its impacts on Earth. The spacecraft's long-term measurements give solar scientists in-depth information to help characterize the interior of the sun, the sun's magnetic field, the hot plasma of the solar corona, and the density of radiation that creates the ionosphere of the planets. The information is used to create better forecasts of space weather needed to protect aircraft, satellites and astronauts living and working in space.

SDO: Year 5

Video above:

February 11, 2015 marks five years in space for NASA's Solar Dynamics Observatory, which provides incredibly detailed images of the whole sun 24 hours a day. Capturing an image more than once per second, SDO has provided an unprecedentedly clear picture of how massive explosions on the sun grow and erupt ever since its launch on Feb. 11, 2010. The imagery is also captivating, allowing one to watch the constant ballet of solar material through the sun's atmosphere, the corona.

In honor of SDO's fifth anniversary, NASA has released a video showcasing highlights from the last five years of sun watching. Watch the movie to see giant clouds of solar material hurled out into space, the dance of giant loops hovering in the corona, and huge sunspots growing and shrinking on the sun's surface.

The imagery is an example of the kind of data that SDO provides to scientists. By watching the sun in different wavelengths – and therefore different temperatures – scientists can watch how material courses through the corona, which holds clues to what causes eruptions on the sun, what heats the sun's atmosphere up to 1,000 times hotter than its surface, and why the sun's magnetic fields are constantly on the move.

Five years into its mission, SDO continues to send back tantalizing imagery to incite scientists' curiosity. For example, in late 2014, SDO captured imagery of the largest sun spots seen since 1995 as well as a torrent of intense solar flares. Solar flares are bursts of light, energy and X-rays. They can occur by themselves or can be accompanied by what's called a coronal mass ejection, or CME, in which a giant cloud of solar material erupts off the sun, achieves escape velocity and heads off into space. In this case, the sun produced only flares and no CMEs, which, while not unheard of, is somewhat unusual for flares of that size. Scientists are looking at that data now to see if they can determine what circumstances might have led to flares eruptions alone.

Goddard built, operates and manages the SDO spacecraft for NASA's Science Mission Directorate in Washington, D.C. SDO is the first mission of NASA's Living with a Star Program. The program's goal is to develop the scientific understanding necessary to address those aspects of the sun-Earth system that directly affect our lives and society.

For more information about Solar Dynamics Observatory (SDO), visit: http://www.nasa.gov/mission_pages/sdo/main/

Image, Video, Text, Credits: NASA/SDO.

Greetings, Orbiter.ch

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