It’s that time of year again this Easter. Comet 12P/Pons-Brooks, a chunk of ice and dust around 34 kilometers in size, is on its way to the closest point of its orbit to the sun, which it will reach on 21 April 2024. Vaporizing parts of its icy comet nucleus, it approaches our sun approximately every 71 years, hurling more and more gas and dust into space. The gases, especially the carbon molecule C2, create the green glowing coma that envelops the nucleus. As C2 decays after several hours, the tail rarely glows green. Typical of 12P/Pons-Brooks are its explosive gas eruptions, which produce additional, bright extensions and thus create these filigree structures.
The comet is best visible now, at the end of March and beginning of April in the early evening directly after sunset, low above the western horizon slightly to the right of Jupiter. Its brightness increases until mid-April and it can be easily seen with binoculars at mag4 under a clear sky. However, like most comets, it is strikingly green and has a beautiful tail in astrophotos, but it is less spectacular with the naked eye or binoculars and can usually only be seen as a bright diffuse patch of light