A Glorious Voyage to the Sun
Summer is nearly upon us, marking the onset of hot sunny days under crystal-clear skies. What better way to usher in the new season than observing, up-close, the reason for the season — our star, the Sun. We are now in the midst of a particularly fabulous year for catching the Sun spewing amazing activity our way!
While we could never survive a trip to the Sun, being incinerated long before reaching our destination, we can observe the Sun in fine detail from telescopes on Earth and in space, and even right here in Raleigh through an observing extension of the Astronomy & Space Observation Lab at the Nature Research Center (NRC).
Today, NRC astronomers Dr. Rachel Smith and Dr. Patrick Treuthardt conducted the first successful public solar observing of 2013. Under bright blue skies on the 4th floor terrace of the NRC, we observed gorgeous solar prominences, sunspots, and granulation features on the Sun through our Coronado 90-mm solar telescope — an instrument specially designed to filter all wavelengths of light with the exception of Hydrogen-alpha (“H-alpha”), rendering safely to our eyes the Sun as a glorious orange sphere of hydrogen gas. Observing the Sun in H-alpha also delineates the complex layer of the Sun called the chromosphere, where many interesting manifestations of solar activity can be observed.
The image below, taken last year with the Coronado telescope, illustrates many of the highlights from today’s observing which we can observe weekly on clear days, during solar viewing at the NRC:
1. Solar prominences: These are seen extending beyond the edge, or limb, of the Sun (they look like “peach fuzz” lining the surface, above). Prominences are complex clouds or streams of gas above the chromosphere — the layer of the Sun we observe in Hydrogen-Alpha. A prominence can form in one day, and stable ones can last for several months. While these prominences appear small compared to the surface, they in fact extend thousands of miles into space (note that about 100 Earths could fit across the surface of the Sun, and about 1 million Earths could fill it up!). The red loops of the solar prominences are comprised of hot plasma made of hydrogen and helium which flow along the twists and turns generated by the Sun’s magnetic field.
2. Filaments. These are prominences seen against the surface of the Sun. In H-alpha, they appear as darker, worm-like structures on the face of the image.
3. Sunspots. These are dark spots seen on the surface of the Sun. They contain strong magnetic fields which emerge through the solar surface and cool the area from about 6000 to 4200 degrees-C, and appear as a dark spot against the brighter, hotter photosphere. A large sunspot, along with a few smaller ones, can be seen in the image above. Sunspots take about 27 days to make a complete rotation as seen from Earth, and last from days to weeks.
4. Plage. These are patchy surface brightenings seen in H-alpha, and are visible local to the large sunspot in the image above. These are associated active regions of the surface, and are associated with vertically-emerging or reconnecting magnetic field lines.
5. Granulation. This appearance gives the surface a mottled appearance, and is the result of convection operating below the photosphere, producing columns of gas reaching several hundred miles in diameter just below the photosphere. The granular appearance is due to convection currents resulting from the heating and cooling of the gas columns.
The layers of the Sun highlighted above are shown here:
Viewing the Sun through specialized filters is very exciting indeed, but there are also sophisticated scientific missions currently ongoing to study solar activity and space weather. The years 2013-2014 are predicted to be an exciting period of solar maximum — years when sunspots, and consequently solar activity and space weather, are at their most prevalent:
Solar astronomers are very interested in studying these periods of high solar activity, as they inform the evolutionary process of stars and solar systems, they could have a long-term effect on life on Earth, and not to mention the short-term effects on modern technology. While no data to date predict a near-future catastrophic event stemming from space weather, the following image illustrates possible infrastructure that could be affected by such events:
With NASA’s fleet of solar missions currently monitoring the Sun, we should feel very prepared for this next round of solar activity, and as an astronomer I am particularly excited to observe evidence of this both directly at the NRC and through online resources stemming from the state-of-the-art solar instruments now in operation. These include the Solar Dynamics Observatory (SDO) (mission to understand the Sun’s influence on Earth and near-Earth space), Solar and Heliospheric Observatory (SoHO) (mission to study the Sun’s core, surface and wind), and Solar Terrestrial Relations Observatory (STEREO) (mission to study specific emissions of the Sun through stereoscopic images), among others.These missions continue to provide new information and fantastic visualizations of the Sun, in unprecedented and awe-inspiring detail.
The video below from the Solar Dynamics Observatory is, in my view, one of the best illustrations of the awesomeness of our Sun — the only star, as far as we know, which supports a living planet. In this video you will see a magnificent solar flare — a sudden brightening of the solar surface related to a gigantic release of energy, equivalent to billions of megatons of TNT — as it flows, like a dance, over the magnetic field lines emanating from the surface. The beautiful display of “coronal rain” results from interactions of solar material with the magnetic field.
In 5 billion years or so the Sun will expand to become a Red Giant and in its death throes will likely swallow up the Earth (humans will be long gone by this time). In the meantime, we can marvel at this giant burning ball of gas — the reason for the season, and our existence.
Please join us for weekly solar observing at the NRC (weather permitting)! We are now testing new equipment to enhance the observing experience, and we hope you will join in our ongoing observing experimentation! Click here for the weekly schedule.
REMEMBER! NEVER LOOK AT THE SUN WITH YOUR BARE EYES, OR THROUGH ANY GLASSES OR LENSES NOT SPECIFICALLY DESIGNED FOR SOLAR OBSERVING!