Faculty Voice: Watching the total eclipse — when 99.9% just isn’t good enough

The sun's faint atmosphere, known as the corona, is always present. The brightness of the light emitting from the sun's main disk often hides this faint atmosphere. The uneclipsed sun is 100,000 to a million times brighter than the corona.

Imagine being in a dark room, looking at a phone. When the brightness is low, the screen is visible just fine. However, outside in bright sunlight, a phone's screen brightness must increase for anything to be seen. And even then, it's hard to see what's on the screen. If the automatic screen brightness adjustment is disabled, the screen isn't visible until the brightness is adjusted.

Viewers witnessing an eclipse experience a similar effect when they look at the corona, which is significantly fainter than the main disc of the sun.

Consider that when 99% of the sun is eclipsed, 1% of the sun is still showing. The sun is 100,000 times brighter than the corona, so even that 1% sliver of sun is at least 1,000 times brighter than the corona.

Similarly, if the sun is at 99.9% partial eclipse, 1/1,000 of the sun is still visible. That's still 100 times brighter than the corona. That's still too much light to experience the glory of a total solar eclipse. Outside the path of totality - even at 99.9% partial eclipse, it will NOT get dark.

Those who witness the full awesomeness of a total solar eclipse within the PoT are in for a treat. Here are a few things PoT viewers will experience firsthand:

• Temperature and wind changes.
• Behavioral changes in animals.
• Shadow bands.
• Dramatic changes in brightness and darkness.
• Baily's beads (beads of sunlight caused by the moon's topography right before totality).
• Diamond ring effects.
• Chromosphere and prominences.
• The main attraction: the corona.
• Sunset colors around the horizon.
• Bright stars and planets.