|Drops of mercury.|
One of them concerns massive volcanic eruptions. In Earth's history, there were times when huge swathes of the Earth erupted in furious volcanic activity -- thousands and thousands of miles of eruptions. If this ever happened in our time, it would be an extinction-level event. So that's one worry: I fear the air will become unbreathable and that it will happen swiftly.
But supernovae (okay, comets too) are my biggest worry. That post I put up recently, asking if readers wanted to worry and suggesting a link to fill this need, led to a story about the possibility of nearby suns going nova. I do worry about this. It would happen so quickly: seven billion humans one moment; a dead planet the next. This is often suggested as a possible reason why the universe may have little opportunity to produce intelligent life -- they get picked off by supernovae before they can really get going.
At this point, let us enter the darkest realm of Keith-worries, stuff that's not likely but worries me anyway. I'm not at all convinced that we know enough about our sun to say that it's going to last another five billion years. That's the standard line from scientists -- but every day you see stories that suggest our understanding of what happens in our own sun is flawed.
One day I was a passenger in a car on the Taconic and I looked up at the sky and was shocked by what I saw. The sun looked exactly like a disc of mercury (similar to the photo above). It was silver and looked like liquid! For a brief moment, I thought the sun had gone nova and this was the instant just before the shock wave hit us. Luckily, I also knew it takes only eight seconds for light to travel from the sun to the Earth -- so as soon as that brief time had elapsed without an impact or a change in the sun's appearance, I knew I had been wrong. I let out a long breath of air: we would live to see another day.
But my heart was still pounding. For a moment there I had really believed a supernova was happening. I wish you could see how the sun looked that day. Then you might understand my reaction. I've never seen a sun like that, before or since.
I worry -- not endlessly, not insanely -- but I worry. Have you ever seen the sun do this trick? And if so, did it also freak you out?