There are a few astronomical events that, even though they recur, are once-in-a-lifetime occasions, separated by too much time for all but the luckiest to see twice. For me, Halley’s Comet in 1986 was such an occasion. I lifted my three-year-old son to the eyepiece of my telescope so he could perhaps say, 76 years later, that he had seen the comet twice! In truth, however, he couldn’t really see it, and doesn’t remember the moment. Ah, well.
There is another such event coming up, perhaps by the end of September and very likely before the end of the year. It is a recurrent nova, T Coronae Borealis. This article does a very good job of explaining what it is and how it works.
I have a couple of things to add to that account. If you’re like me, you may read this sentence
- If people observed these “recurrent novae” when they happened in the past, scientists can compare how light from the system changed in the lead-up to each outburst and look for similar behavior today.
and ask yourself just what that similar behavior might be. Measuring how the brightness of the system changes is the answer. Here is the “light curve” from the last time this nova erupted, in 1946. Brightness increases as you go up the graph.
https://upload.wikimedia.org/wikipedia/commons/thumb/4/44/TCrBLightCurve.png/1280px-TCrBLightCurve.png
And if seeing that the nova will lie between Arcturus and M13 doesn’t do much for you, this diagram might help. It shows the sky from about latitude 37 degrees north, at 9:30 pm on September 20. T Coronae Borealis is in the red “bulls-eye.”
Image from The Sky software, created by Neal Sumerlin
Watch the news for word of this! It should be easily visible, but will fade in a few days. And hope for clear skies!