Comet 12P/Pons-Brooks is brightening and can be seen in the western sky after sunset with a good pair of binoculars and good viewing conditions (dark and clear).
Discovered in 1385, Comet Pons-Brooks returns every 71 years. Its ion tail, visible in deep camera exposures, is pushed by solar wind and points away from the Sun. The comet may brighten enough to be visible during the April 8 solar eclipse!
The green color seen in the coma of most comets, but not in their tails, is due to emissions from Diatomic carbon C2 (aka dicarbon) molecules.
Sunlight heats the comet’s ice and organic material to produce C2 molecules, which break apart in ~2 days before they reach the tail. C2 is excited by solar UV radiation and emits mostly in infrared but its triplet state radiates at 518 nm (d3Πg → a3Πu transition below).
#Comet#12P#PonsBrooks last night. Proper tail now, even with my unguided 10 year old P&S (Canon G7 X, 240x5s, ISO 800, 100mm EFL, aligned on the comet and stacked with hacky #gmic scripts and tortured in #gimp)
#Timelapse of the frames used for that #Comet#12P#PonsBrooks shot up thread. So many more satellites, a few years ago I'd expect maybe 3-4 or in a shot like this. Doesn't really affect anything in this case (unlike the airplanes, which were bright enough to show up in a 240 frame average after stretching) but definitely noticeable https://flic.kr/p/2pH2hqi
#Comet#12P#PonsBrooks (very faintly visible, upper left) over the #Moon last night. This is a somewhat fake composite of 100 4 second frames, aligned separately on the stars, moon and foreground. Too close to twilight to get much of the comet
#Comet#12P#PonsBrooks (bottom center) below the #Moon last night, a bit later, more exposure and more frames than the previous shot. Again somewhat fake: Composite of the same stack aligned separately on the moon and stars.
Also visible: #Jupiter, Callisto, Ganymede, maybe Europa if you squint at the glare around Jupiter, and #Uranus (relatively bright blueish object almost directly above Jupiter) #Astrophotography#Astrodon