Seeing the Sun in a New Light
April 21, 2010 will be remembered as the day we saw the sun in a new light. NASA showcased the Solar Dynamics Observatory (SDO) 'first light' imagery of the sun, photographs that are 10 times the clarity of a household high definition television. After decades of solar physics research, the advanced instrumentation aboard the SDO will answer many mysteries about our nearest star and will no doubt uncover new questions. Already, solar physicists are examining whether long-standing solar theories are holding true, and the SDO's sheer power will help scientists protect the Earth against potentially paralyzing space weather. In this multicolored image, multiple wavelengths of extreme ultraviolet light (EUV) from the SDO's AIA (Atmospheric Imaging Assembly) instrument have been overlaid, highlighting solar plasma at temperatures of 60,000 Kelvin (glowing in red) to over 1 million Kelvin (blue and green). The high definition of this instrument means very tiny magnetic structures can be resolved. The AIA is continually filming the sun, tracking energetic events like coronal mass ejections (CMEs) and flares.
A Prominence Erupts
As part of the NASA SDO first light release, the spacecraft was lucky to capture the eruption of a prominence, a huge arc of plasma expanding into space from the solar surface (the photosphere) high into the solar atmosphere (the corona). Typically, solar prominences measure ten times the diameter of Earth. In this series of images from a prominence eruption movie, SDO captured very fine detail in plasma structure; magnetic field lines knotting together as the prominence expanded, climbing high above the sun's limb.
An Internal Struggle
The SDO isn't only keeping tabs on the dynamics of the solar atmosphere, it is able to measure oscillations inside the sun, gaining a better idea about how sunspots form, flares are triggered and how energy flows through the solar body. The HMI (Helioseismic and Magnetic Imager) instrument is gathering data about this seismic activity (a method known as "helioseismology") and magnetic polarity. As the sun is a jumble of tightly wound magnetic fields, north and south magnetic poles can be found dotted all over the solar surface. Tracking magnetic polarity as the magnetic field pushes through the solar surface will ultimately help solar physicists understand what makes the sun tick, aiding space weather prediction methods.
As a solar flare or CME erupts, a vast amount of energy is released, rapidly heating solar plasma. By studying the lower corona in EUV wavelengths, heating mechanisms can be studied and tracked. As shown here, the solar surface is covered in loops of magnetism filled with million degree plasma, a fertile region for explosive events.
Our Variable Star
The Extreme ultraviolet Variability Experiment (EVE) on the SDO is being used to detect ultraviolet light across many frequencies. Understanding how this radiation fluctuates will help space weather scientists see how it influences our atmosphere, heating the thermosphere of the Earth and changing our ionosphere. Changes in the ionosphere are known to impact global communications, so understanding how EUV emission varies is critical.
BIG PIC: Diving Deep into a Solar Prominence (SDO First Light)