In essence, coronagraphs work by creating a false eclipse in space and revealing the Sun's faint corona. What this means for us is that for a few brief minutes during the eclipse totality, observers on Earth will be seeing more or less exactly what our telescopes are seeing in space—and that might include a comet!

Historically, comets have been seen during eclipses. During the eclipse of 1882 a very bright Kreutz sungrazer was seen next to the Sun, and in 2008 it seems that Miloslav Druckmuller might have fortuitously imaged a SOHO sungrazer. So we're not talking of something unprecedented here, but we're going to need a lot of luck.

Slim Odds



There are several possible wrinkles this year in our quest to see an eclipse comet. First, we can't predict when sungrazing comets will come along, and if we're really lucky, we'd only get maybe a day's advance notice that one will be near the Sun during the eclipse. SOHO/LASCO discovers a new comet every three days on average throughout the year, but some some months are better/worse than others for reasons relating to viewing geometry, and as luck would have it August is one of the worst months. Numerically, I'd say we have around a 5 percent chance of a comet being near the Sun during totality. Not great, but not zero!

The second wrinkle is that even if we have a comet near the Sun, it could be really faint and at the very least, technically challenging to observe. I've put together the image below that shows the general area in which a generic Kreutz-group comet would be found. The image assumes a south-facing observer in Tennessee, but the geometry will change only minimally for other locations. The position of the track will not change relative to where Mars and Venus are, so they are good guides. Barring an exceptionally bright comet, any sungrazers near the Sun will be fainter than Mars or Venus, so if you can't see those then a comet is unlikely. For experienced observers, I'll be producing ephemerides should a comet happen along. Details on that in a moment.