Sunrise, sunset. It’s been going on for billions of years.
Artists of all sorts rely on seeing and recording light. Good light is ethereal, difficult to master in art but when done well, draws us into the work.
This light, this source of inspiration, comes from our lucky star, the Sun. It’s as reliable as, well, the Sun. On closer inspection, this reliable and inspirational source of light isn’t what it seems. It’s billions of H-bombs all going off at once all the time! Still, we admire its light and bask in its warmth, sometimes too long and feel the sting of sunburn. That seems the worst it can do.
In the Greek moral story about Icarus, he gets too close to the Sun and his wings of feathers and wax come apart. Icarus falls into the sea and drowns. The moral is to not be complacent, or reckless. Use your noggin! We have come a long way in that respect, at least when it comes to the Sun.
We have examined the Sun, up close from afar by using telescopes and instruments to measure the Sun’s magnetic fields, temperatures, plasma/ion winds. We send spacecraft to study the Sun from closer distances, knowing full well to protect them. No melting circuits please. The closer we get the scarier our Sun becomes. Our consistent, placid Sun when seen up close is a maelstrom. Let’s dive into the Sun in our star proof space capsule.
Even before takeoff we are in the Sun’s influence. Visible light, some infrared and ultraviolet bathes us as we prepare. Earth’s atmosphere and magnetic field do a wonderful job of protecting us from x-rays, gamma rays, ultraviolet, and the Sun’s plasma wind of electrons and protons. After takeoff things change a lot. All those nasty things are attacking our craft. Fortunately, even if we were not in an impervious cocoon their density is low so exposure in less protected craft is tolerable but cumulative.
We exist in the Sun’s tenuous atmospheric wind called the heliosphere, a region stretching from the Sun to beyond Pluto. When we are just a few million miles from the Sun we enter the corona, and the temperature rises like a shot! It’s gets as hot as 3 million degrees kelvin in the corona. Plasma in the corona is twisted and loopy, due to twisted magnetic fields. We next slip through the transition region, where helium becomes fully ionized, like steam from boiling water. Still in the atmosphere we dive into the chromosphere, where blade-shaped spicules of plasma form and dissipate, like bubbles in boiling water.
Then we hit paydirt, the photosphere. This is the most visible part of our Sun where sunspots, solar prominences, filaments, and granules appear to form. More on that next time.
What’s in the Sky?
August 12; after 1am; northeast: The grand Perseid meteor shower peaks. The last quarter Moon interferes a bit.