Advanced Imaging


Advanced Imaging Magazine

Updated: January 12th, 2011 09:49 AM CDT

Mission (Not) Impossible

Five-year Solar Dynamics Observatory satellite will investigate causes of the sun’s variability and how it produces space weather that affects us on earth
NASA’s Solar Dynamics Observatory (SDO), which was launched in February, is sending back high-resolution images of the sun. SDO will help scientists learn how solar activity is created and how space weather results from that activity. NASA says it will measure the sun’s interior, magnetic field, the hot plasma of the solar corona, and the irradiance. (Images courtesy NASA unless otherwise noted)
The Earth is superimposed on a solar eruptive prominence as seen in extreme UV light (March 30, 2010) to give a sense of how large these solar eruptions are.
As the arcing loops above an active region began to rotate into a profile view, SDO captured the dynamic, magnetic struggles taking place. Particles spiraling along magnetic field lines trace their paths. Magnetic forces in the active region are connecting, breaking apart, and reconnecting. These images were taken in extreme ultraviolet light.
NASA/ESA/Williams College Eclipse Expedition
On July 11, the new moon passed directly in front of the sun, causing a total solar eclipse in the South Pacific. In this image, the solar eclipse is shown in gray and white from a photo provided by the Williams College Expedition to Easter Island and was embedded with an image of the sun's outer corona taken by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft and shown in red false color. LASCO uses a disk to blot out the bright sun and the inner corona so that the faint outer corona can be monitored and studied. The dark silhouette of the moon was covered with an image of the sun taken in extreme ultraviolet light at about the same time by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory.

By Barry Hochfelder

Everyone remembers the lesson from school: the sun is 149.6 million kilometers (93 million miles) from earth. We know it’s hot (5,500° C or about 9,900° F on the surface, while at the core it’s something on the order of 15 million° C or 27 million° F), almost perfectly round, dense (its mass is almost 330,000 times that of Earth), and about 73 percent hydrogen, 25 percent helium and 2 percent other gasses. And we know that without it, life on earth would cease to exist.

So, what more do we need to know? That’s the job of NASA’s Solar Dynamics Observatory (SDO). Imaging will play a major role as the SDO studies how solar activity is created and how space weather results from that activity. NASA says it will measure the sun’s interior, magnetic field, the hot plasma of the solar corona, and the irradiance.

SDO is one of two groups of mission spacecraft in NASA’s Living With a Star (LWS) program. The other is Geospace Missions Network, consisting of spacecraft in the magnetosphere and ionosphere to define the Geospace response to solar and solar wind input.

Solar wind is a continuous stream of plasma. In addition, the sun periodically releases billions of tons of matter in what are called coronal mass ejections. These are immense clouds of material that, when directed towards earth, can cause large magnetic storms in the magnetosphere and the upper atmosphere. Magnetic storms cause many noticeable effects on and near earth. They include the Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights); communications disruptions, radiation hazards to orbiting astronauts and spacecraft; current surges in power lines; orbital degradation; and corrosion in oil pipelines.

“SDO will improve our understanding of the physics behind the activity displayed by the sun’s atmosphere, which drives space weather in the heliosphere, the region of the sun’s influence, and in planetary environments,” according to a NASA mission guide. “SDO will determine how the sun’s magnetic field is generated, structured and converted into violent solar events that cause space weather. SDO observations start in the interior of the sun where the magnetic field that is the drive for space weather is created. Next, SDO will observe the solar surface to directly measure the magnetic field and the solar atmosphere to understand how magnetic energy is linked to the interior and converted to space weather causing events. Finally, SDO will measure the extreme ultraviolet irradiance of the sun that is a key driver to the structure and composition of the earth’s upper atmosphere.”

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