[Solar System] Submission 142093 – Bruce Charlier

On the 7th and 8th June 2024, Earth passed through the elliptical and highly inclined orbital plane of comet 12P/Pons-Brooks – a Halley-type comet with an orbital period of 71 years. In the preceding weeks, the comet had been putting on a good show for southern observers with daily changes in its well-developed ion tail and its fan-shaped dust tail - getting higher in the sky each day although becoming more distant. As Earth approached the orbital plane of the comet, the dust tail began to form an anti-tail where it appeared in front of the comet's coma and increasingly opposite to the blue ion tail. On passing through the orbital plane over those two days in early June, the anti-tail then appeared as a prominent spike surrounded by a more diffuse area, pointing directly geometrically opposite to the ion tail and yielding the view captured here. This unique perspective shows the disc of dust shed off in the comet’s wake as seen side on, where the larger dust particles are more concentrated closer to the plane of travel thus forming the prominent spike. The bluish ion tail shows a well-developed structure and the linear streams leaving the nucleus have quickly become contorted by the solar wind as they move away. The green glow of the comet's coma comes from the dissociation of diatomic carbon molecules, although this is being viewed through the dust tail here such that it is somewhat obscured. Timing was crucial in capturing this image - I only had around 1.5hrs of astronomical night before the comet was too low in the west to image. This image shows the position of the comet as it was at 06.13 UTC on the 7th June 2024 against the background of stars in Lepus, including towards the top of the image NGC 2196 – a spiral galaxy ~100 million light years away. 13 x 2 mins each RGB subs, Takahashi TOA130 with 35 reducer giving f5.4 and a focal length of 698, AP1200 GTO mount, ASI62000mm Pro CMOS camera, Chroma RGB filters, imaged from my observatory at Star Field, Wairarapa, NZ