(C) Daily Kos This story was originally published by Daily Kos and is unaltered. . . . . . . . . . . Comet C/2023 P1 (Nishimura) makes closest approach to Earth [1] ['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.'] Date: 2023-09-11 Comet C/2023 P1 (Nishimura), a recently discovered comet, it putting on a show in the pre-dawn skies. It is currently about 0.84 AU from Earth, 0.33 AU from the Sun (1 AU = average Sun-Earth distance = 150 million km). Closest approach to earth is tomorrow, Sep 12, perihelion (closest approach to the Sun) is on Sep 17. It is one of the brighter comets, current at magnitude 4, it is sporting a nice long tail, but it is difficult to see due to its proximity to the Sun and the low elevation angle in the sky before sunrise. A pair of binoculars and clear skies will help. x Comet Nishimura C/2023 P1 2023 sep. 8 4.48 UT 10x60sec Zeiss-Milvus f-135/2.5 Nikon Z50mod ISO 400 Michael Jäger pic.twitter.com/rDcQflTuQD — Michael Jäger (@Komet123Jager) September 9, 2023 Here is the path across the morning sky of Comet C/2023 P1 (Nishimura) as seen from the USA. It should not be difficult to locate, near the Leo constellation in the East, but it will be low in the dawn sky, so observability will be challenging depending upon local conditions. After Sep 17, it will be visible only from the southern hemisphere after sunset. From the northern hemisphere, it will appear to the left of the setting sun. Here is the predicted light curve of Comet C/2023 P1 (Nishimura) and the actual measured values so far. Current apparent magnitude is below 4 (lower is brighter). In theory, objects with mag 6 and lower are visible to the naked eye, but currently the comet is low on the horizon during the early morning hours, so visibility depends on local conditions. Binoculars will help. A long exposure shot with a good camera and a tripod will help image the tail. Here are some vital stats on Comet C/2023 P1 (Nishimura) - Parameter Value Date Closest approach 0.838 AU from Earth Sep 12, 2023 09:20 Perihelion 0.225 AU from Sun Sep 17, 2023 Aphelion 114 AU 110 AU 1800 2200 Orbital Period ~435 years inbound ~407 years outbound Previous Perihelion - July 1588 Magnitude ~6 ~3.3 ~2.7 Sep 3, 2023 Sep 12, 2023 Sep 17, 2023 Origins Comet C/2023 P1 (Nishimura) has a period of ~435 years and last visited the inner solar system in 1588. Its orbit extends out to 114 AU, far beyond the orbit of Neptune and Pluto. Its orbit is steeply inclined relative to the ecliptic by about 132 degrees. Here is a map of the inner solar system and the path of Comet C/2023 P1 (Nishimura) over the next few weeks. Discovery Comet C/2023 P1 (Nishimura) was discovered by Japanese amateur astronomer Hideo Nishimura quite recently on Aug 12, 2023, when the comet was 1.0 AU from the Sun. Pre-discovery images from Jan 19, 24, and 25, 2023 from PanSTARRS were subsequently identified. Nishimura has discovered or co-discovered 3 comets, 23 Novas and 17 variable stars. https://www.cometchaser.de/discoverystories/Comet-discoverers.html Image credit: Hideo Nishimura Some notable images This first image was posted on the NASA APOD site today. It was taken in eastern Slovakia by Petr Horálek / Institute of Physics in Opava. This beautiful image of comet C/2023 P1 Nishimura was taken by Jeremy Perez, art director and photographer in Flagstaff, AZ. x C/2023 P1 (Nishimura) Saturday morning from Cinder Hills Overlook/Sunset Crater. Too early in the morning for good sense and tough to spot as it rose. Twilight really hit it hard, but the tail was still decently long—about 6 degrees in this pic. pic.twitter.com/30Ec7DIunD — Jeremy Perez (@jperez1690) September 10, 2023 Comet C/2023 P1 (Nishmura) over Stonehenge. x Comet Nishimura (C/2023 P1) over Stonehenge. ☄️ Discovered last month by amateur astronomer Hideo Nishimur, the comet will reach its closest point to Earth tomorrow (12 Sept). If you’re an early riser, you may be able to catch a glimpse before sunrise. 📷: Nick Bull pic.twitter.com/j9a3YMsa41 — Stonehenge (@EH_Stonehenge) September 11, 2023 The Color Green Here is some info for those with an interest in physics and chemistry. The green color is seen in the coma of most comets, but not in their tails. It is due to emissions from quad-bond Diatomic carbon (aka dicarbon) molecules. 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. 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, seen as green by our eyes. Epilogue I hope you get a chance to see this icy visitor from the outer parts of the solar system. It will not be easily visible after the next few days. If you don’t get a chance to see it, we can always watch vicariously through the eyes and cameras of others. Check out theskylive.com/… and starwalk.space/… for more info on how to see the comet. Please post any images you have already captured of the comet. 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