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).
The green color seen in the coma of most comets, but not in their tails, is due to emissions from quad-bond Diatomic carbon (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.
Diatomic carbon C2 is a green, gaseous inorganic chemical. It is unstable at ambient temp. and pressure (it polymerizes).
It is found in flames, comets, stars and the interstellar medium.
From https://www.pnas.org/doi/10.1073/pnas.2113315118 -
"This work shows that, to break the quadruple bond of C2 using sunlight, the molecule must absorb two photons and undergo two “forbidden” transitions." (spin conservation and the Born–Oppenheimer approx).
Comet C/2023 E1 ATLAS is currently swinging by the inner solar system and is at its brightest around magnitude 9, visible in the northern sky using telescopes.
This image was captured on July 9, few days after Perihelion on July 1, by Austria-based comet hunter and astrophotographer Dan Bartlett.
The green color seen in the coma of Comet C/2023 E1 (ATLAS) and other comets, but not in their tails, is due to emissions from quad-bond Diatomic carbon (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.