Posted on Mar 8, 2021

APOD: 2021 March 8 - Three Tails of Comet NEOWISE

Maj William W. 'Bill' Price

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Good morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Three Tails of Comet NEOWISE." Did you get a glimpse of Comet NEOWISE this past summer? I bet it didn't look like this. Taken from Brittany, France, NEOWISE sports not two, but three tails. The white tail is the dust tail, blue tail is the ion tail (or gas tail), but what is causing the red tail? Answer: Sodium. Also called the cometary neutral tail, the source of the sodium atoms and how the neutral tail forms is still a matter of debate. One idea is that the sodium atoms are formed in the coma and pushed out into the neutral tail through radiation pressure. The neutral tail is therefore formed in a similar way to the dust tail, an idea that is supported by the location of the neutral tail between the dust tail and the ion tail.

An alternate idea is that the sodium atoms are created in situ in the tail through either collisions between dust grains or the bombardment of the dust grains with ultraviolet light from the Sun. This releases the sodium atoms in a process called sputtering. In either case, the neutral tail shines due to fluorescence, by absorbing solar photons and re-emitting them at 5,890 angstroms as the sodium atom de-excites.

APOD: 2021 March 8 - Three Tails of Comet NEOWISE

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LTC Stephen F.

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Blue Comet Blues

Provided to YouTube by Universal Music GroupBlue Comet Blues · Bill Haley & His CometsRock'n Roll Stage Show A Geffen Records Release; 1956 UMG Recordings...

Thank you my friend Maj William W. 'Bill' Price for posting the NASA Astronomy Picture of the Day (APOD) is titled "Three Tails of Comet NEOWISE."

Image: Three Tails of Comet NEOWISE - Image Credit & Copyright - Nicolas Lefaudeux

APOD background
"Explanation: What created the unusual red tail in Comet NEOWISE? Sodium. A spectacular sight back in the summer of 2020, Comet NEOWISE, at times, displayed something more than just a surprisingly striated white dust tail and a pleasingly patchy blue ion tail. Some color sensitive images showed an unusual red tail, and analysis showed much of this third tail's color was emitted by sodium. Gas rich in sodium atoms might have been liberated from Comet NEOWISE's warming nucleus in early July by bright sunlight, electrically charged by ultraviolet sunlight, and then pushed out by the solar wind. The featured image was captured in mid-July from Brittany, France and shows the real colors. Sodium comet tails have been seen before but are rare -- this one disappeared by late July. Comet C/2020 F3 (NEOWISE) has since faded, lost all of its bright tails, and now approaches the orbit of Jupiter as it heads back to the outer Solar System, to return only in about 7,000 years."

Blue Comet Blues
https://www.youtube.com/watch?v=ZTiTG660hSg

FYI COL Mikel J. Burroughs SMSgt Lawrence McCarter Lt Col John (Jack) Christensen LTC (Join to see) SCPO Morris Ramsey MAJ Dale E. Wilson, Ph.D. Maj Bill Smith, Ph.D. Sgt Albert Castro PO1 William "Chip" Nagel SSG Stephen Rogerson SSG Samuel Kermon SSG Franklin Briant SP5 Geoffrey Vannerson SMSgt David A Asbury A1C Riley Sanders SSG William Jones CPT (Join to see) SGM Bill Frazer

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LTC Stephen F.

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