Just in time for the imminent event of Solar Maximum, when the sun reaches a crescendo in its 11-year cycle of magnetic activity and all the sunspots, solar flares, coronal mass ejections, and other magnetic mayhem that comes with it, Chabot Space & Science Center is opening a new solar exhibition that features the latest in stunning ultraviolet satellite imagery from NASA's Solar Dynamics Observatory!
The exhibition "Touch the Sun" will open on December 22nd—because we figure since the world is NOT ending on December 21st, might as well celebrate.
NASA's Solar Dynamics Observatory, which you will have heard me ramble on about if you're a regular reader of these blogs, is one of the latest and most advanced space-borne solar observatories and has been revealing the wonders of the sun since 2010 as we've never seen them before.
Solar Maximum is in progress as I type and is expected to reach a peak sometime in early 2013. But, as with weather, we won't know exactly when the peak will occur until after it's passed and solar activity begins to relax again, sloping off toward Solar Minimum in the years to come.
The 11-year solar cycle has been known of for a few hundred years now, practically since the time when observers first were able to make routine counts of sunspots using telescopes. Galileo is attributed with being one of the first to make regular observations of sunspots, recording their positions, sizes, shapes, and numbers regularly. After decades of observations by different astronomers a pattern in the rise and fall of sunspot numbers was detected: a fairly regular peak-and-trough pattern over time, with the peak sunspot numbers separated by about 11 years on average.
It was not known at first what sunspots are, but they were eventually identified as effects caused by the presence of strong magnetic fields at the sun's visible surface. Once we began sending scientific instruments into space, outside of Earth's light-obscuring atmosphere, we learned that there is a lot more going on than merely dark spots making cyclical appearances. Observations of the sun's ultraviolet light, X-rays and gamma rays showed us the sun's intensely hot atmosphere and regions of magnetic activity surging up from within the sun -- marking its surface with sunspots on its way out and looping and arcing far outward into space.
The sun is mostly a giant sphere of hydrogen and helium plasma (ionized gas) with an enormous thermonuclear reactor at its core, where pressure and temperature are great enough to cause nuclear fusion, hydrogen nuclei are fused together to form helium nuclei, then release energy in the process -- the same process that powers hydrogen bombs.
Energy liberated at the sun's core makes its way outward, eventually, through various layers of the sun's interior. (One of my opening questions that I put to kids visiting Chabot is, "Why is the sun like an ogre?" Answer: "It has layers." Don't get it? The kids do -- at least, those who have seen the movie Shrek.)
In its final sprint upward to the sun's visible surface, solar plasma rises in enormous, high-speed updrafts called convection cells, with a typical cell being close to the size of a state like California. The motion of all that plasma -- which is essentially electrified gas -- generates magnetic fields, much as the circulating electric current in an electromagnet's coil does.
And that's where sunspots, solar flares, space weather storms and the solar cycle itself come in: they are all effects of the dynamic, ever-lively dance of magnetism generated by the swirling, twisting motions of solar plasma.
Which brings me back to the soon-to-open Touch the Sun exhibition at Chabot.
If you've enjoyed your favorite movie or TV show or a Superbowl game on a nice big high-def plasma TV, you ain't seen nothin' yet. Come experience the biggest and most awesomely stunning plasma display around: the sun. You'll not only get to play with the sun's ogre-like layers, you'll get to play with the stuff of the sun itself: with a 20-inch plasma globe you can pull your own filaments of plasma like electric pizza dough and with a 3-foot "Ferro-fluid" dish you can sculpt your own sunspots with a magnet.
So (punchline alert), come to Chabot on (or after) December 22nd and touch the sun.