APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

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APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by APOD Robot » Wed Apr 29, 2020 4:06 am

Image The Ion Tail of New Comet SWAN

Explanation: Newly discovered Comet SWAN has already developed an impressive tail. The comet came in from the outer Solar System and has just passed inside the orbit of the Earth. Officially designated C/2020 F8 (SWAN), this outgassing interplanetary iceberg will pass its closest to the Earth on May 13, and closest to the Sun on May 27. The comet was first noticed in late March by an astronomy enthusiast looking through images taken by NASA's Sun-orbiting SOHO spacecraft, and is named for this spacecraft's Solar Wind Anisotropies (SWAN) camera. The featured image, taken from the dark skies in Namibia in mid-April, captured Comet SWAN's green-glowing coma and unexpectedly long, detailed, and blue ion-tail. Although the brightness of comets are notoriously hard to predict, some models have Comet SWAN becoming bright enough to see with the unaided eye during June.

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by shaileshs » Wed Apr 29, 2020 4:18 am

It looks so beautiful. One thing I'm wondering - Closest to Earth on May 13 (so good chance we can see it during our night time), closest to Sun around May 27 (means we can't see it in our night time) but then someone predicts it'll be brightest in June means it'll get brighter after going around Sun and on it's way back we can see it with unaided eye ? Thanks to everyone in advance for their answers/comments.

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Chris Peterson » Wed Apr 29, 2020 4:44 am

shaileshs wrote:
Wed Apr 29, 2020 4:18 am
It looks so beautiful. One thing I'm wondering - Closest to Earth on May 13 (so good chance we can see it during our night time), closest to Sun around May 27 (means we can't see it in our night time) but then someone predicts it'll be brightest in June means it'll get brighter after going around Sun and on it's way back we can see it with unaided eye ? Thanks to everyone in advance for their answers/comments.
It's a nighttime object over that entire period, including when it's at its perihelion.
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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Ann » Wed Apr 29, 2020 4:45 am

It's a very beautiful object.

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by orin stepanek » Wed Apr 29, 2020 12:45 pm

Pretty :D
CometSwan_Rhemann_960.jpg
I like pretty 8-)
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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by neufer » Wed Apr 29, 2020 4:31 pm

Click to play embedded YouTube video.

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Joe Stieber » Wed Apr 29, 2020 5:01 pm

shaileshs wrote:
Wed Apr 29, 2020 4:18 am
It looks so beautiful. One thing I'm wondering - Closest to Earth on May 13 (so good chance we can see it during our night time), closest to Sun around May 27 (means we can't see it in our night time) but then someone predicts it'll be brightest in June means it'll get brighter after going around Sun and on it's way back we can see it with unaided eye ? Thanks to everyone in advance for their answers/comments.
While it's technically true that C/2020 F8 will be a nighttime object from mid-May into June 2020, here at my 40°N latitude, it will be above the horizon mostly in the daytime while hugging the horizons at the end of evening twilight and the beginning of morning twilight. For example, at perihelion on May 27, F8 sets about three hours after the sun and rises about three hours before the sun. At that time of the year, twilight is almost two hours long, so it won't be well placed high in a dark sky, but not necessarily impossible or even difficult to see depending on how the brightness actually develops. There are a number of southern hemisphere magnitude estimates from April 28 & 29 in the 5.x range. That’s encouraging.

Peak brightness should be around May 20/21, between its closest approach to earth (May 13) and perihelion (May 27), then it should start to fade, continuing to do so into June. I don’t know why the APOD text seems to imply that C/2020 F8 will reach unaided eye brightness in June, do they really mean May? Of course, the usual disclaimer about comet brightness projections applies.

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Chris Peterson » Wed Apr 29, 2020 5:10 pm

Joe Stieber wrote:
Wed Apr 29, 2020 5:01 pm
shaileshs wrote:
Wed Apr 29, 2020 4:18 am
It looks so beautiful. One thing I'm wondering - Closest to Earth on May 13 (so good chance we can see it during our night time), closest to Sun around May 27 (means we can't see it in our night time) but then someone predicts it'll be brightest in June means it'll get brighter after going around Sun and on it's way back we can see it with unaided eye ? Thanks to everyone in advance for their answers/comments.
While it's technically true that C/2020 F8 will be a nighttime object from mid-May into June 2020, here at my 40°N latitude, it will be above the horizon mostly in the daytime while hugging the horizons at the end of evening twilight and the beginning of morning twilight. For example, at perihelion on May 27, F8 sets about three hours after the sun and rises about three hours before the sun. At that time of the year, twilight is almost two hours long, so it won't be well placed high in a dark sky, but not necessarily impossible or even difficult to see depending on how the brightness actually develops. There are a number of southern hemisphere magnitude estimates from April 28 & 29 in the 5.x range. That’s encouraging.

Peak brightness should be around May 20/21, between its closest approach to earth (May 13) and perihelion (May 27), then it should start to fade, continuing to do so into June. I don’t know why the APOD text seems to imply that C/2020 F8 will reach unaided eye brightness in June, do they really mean May? Of course, the usual disclaimer about comet brightness projections applies.
Models which treat the comet as a sort of ideal object (that is, one which follows a simple outgasing model) put the peak brightness around the first week of June. Peak brightness seldom coincides with perihelion for most comets. What the comet actually ends up doing, of course, is largely unpredictable.
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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Boomer12k » Wed Apr 29, 2020 8:26 pm

Wonderful image...

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by neufer » Wed Apr 29, 2020 10:11 pm

Chris Peterson wrote:
Wed Apr 29, 2020 5:10 pm

What the comet actually ends up doing, of course, is largely unpredictable.
https://en.wikipedia.org/wiki/Halley%27s_Comet wrote:
Click to play embedded YouTube video.
<<In 1687, Sir Isaac Newton published his Philosophiæ Naturalis Principia Mathematica, in which he outlined his laws of gravity and motion. His work on comets was decidedly incomplete. Although he had suspected that two comets that had appeared in succession in 1680 and 1681 were the same comet before and after passing behind the Sun (he was later found to be correct; see Newton's Comet), he was unable to completely reconcile comets into his model.

Ultimately, it was Newton's friend, editor and publisher, Edmond Halley, who, in his 1705 Synopsis of the Astronomy of Comets, used Newton's new laws to calculate the gravitational effects of Jupiter and Saturn on cometary orbits. Having compiled a list of 24 comet observations, he calculated that the orbital elements of a second comet that had appeared in 1682 were nearly the same as those of two comets that had appeared in 1531 (observed by Petrus Apianus) and 1607 (observed by Johannes Kepler). Halley thus concluded that all three comets were, in fact, the same object returning about every 76 years, a period that has since been found to vary between 74 and 79 years. After a rough estimate of the perturbations the comet would sustain from the gravitational attraction of the planets, he predicted its return for 1758. While he had personally observed the comet around perihelion in September 1682, Halley died in 1742 before he could observe its predicted return.

Halley's prediction of the comet's return proved to be correct, although it was not seen until 25 December 1758, by Johann Georg Palitzsch, a German farmer and amateur astronomer. It did not pass through its perihelion until 13 March 1759, the attraction of Jupiter and Saturn having caused a retardation of 618 days. This effect was computed prior to its return (with a one-month error to 13 April) by a team of three French mathematicians, Alexis Clairaut, Joseph Lalande, and Nicole-Reine Lepaute. The confirmation of the comet's return was the first time anything other than planets had been shown to orbit the Sun. It was also one of the earliest successful tests of Newtonian physics, and a clear demonstration of its explanatory power. The comet was first named in Halley's honour by French astronomer Nicolas-Louis de Lacaille in 1759.

Some scholars have proposed that first-century Mesopotamian astronomers already had recognized Halley's Comet as periodic. This theory notes a passage in the Bavli Talmud that refers to "a star which appears once in seventy years that makes the captains of the ships err."

Researchers in 1981 attempting to calculate the past orbits of Halley by numerical integration starting from accurate observations in the seventeenth and eighteenth centuries could not produce accurate results further back than 837 due to a close approach to Earth in that year. It was necessary to use ancient Chinese comet observations to constrain their calculations.>>
Art Neuendorffer

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Chris Peterson » Wed Apr 29, 2020 10:28 pm

neufer wrote:
Wed Apr 29, 2020 10:11 pm
Chris Peterson wrote:
Wed Apr 29, 2020 5:10 pm
What the comet actually ends up doing, of course, is largely unpredictable.
https://en.wikipedia.org/wiki/Halley%27s_Comet wrote: Researchers in 1981 attempting to calculate the past orbits of Halley by numerical integration starting from accurate observations in the seventeenth and eighteenth centuries could not produce accurate results further back than 837 due to a close approach to Earth in that year. It was necessary to use ancient Chinese comet observations to constrain their calculations.>>
Of course, I'm talking about what the comet does in terms of its brightness and outgasing, not its orbit, which is typically more predictable, or predictable over a reasonably long period. This comet, however, has an eccentricity near one, so its orbital period is at least thousands, possibly millions of years (possibly even hyperbolic, never to return). It's orbit will continue to be modified by its activity. Only after it moves away from the Sun, becomes largely inactive, and can be tracked for weeks or months will its orbit be known with some accuracy. Quite different from a short period comet like Halley, with its orbit regularly perturbed by Jupiter, and to a lesser degree, Saturn.
Chris

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by neufer » Wed Apr 29, 2020 11:15 pm

Chris Peterson wrote:
Wed Apr 29, 2020 10:28 pm

Of course, I'm talking about what the comet does in terms of its brightness and outgasing, not its orbit, which is typically more predictable, or predictable over a reasonably long period. This comet, however, has an eccentricity near one, so its orbital period is at least thousands, possibly millions of years (possibly even hyperbolic, never to return). It's orbit will continue to be modified by its activity. Only after it moves away from the Sun, becomes largely inactive, and can be tracked for weeks or months will its orbit be known with some accuracy. Quite different from a short period comet like Halley, with its orbit regularly perturbed by Jupiter, and to a lesser degree, Saturn.
Of course, I'm talking about the chaotic motion of those Bill Haley dancers:
Swinging Mitch Feigenbaum and his partner.
Art Neuendorffer

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Re: APOD: The Ion Tail of New Comet SWAN (2020 Apr 29)

Post by Chris Peterson » Wed Apr 29, 2020 11:43 pm

neufer wrote:
Wed Apr 29, 2020 11:15 pm
Chris Peterson wrote:
Wed Apr 29, 2020 10:28 pm

Of course, I'm talking about what the comet does in terms of its brightness and outgasing, not its orbit, which is typically more predictable, or predictable over a reasonably long period. This comet, however, has an eccentricity near one, so its orbital period is at least thousands, possibly millions of years (possibly even hyperbolic, never to return). It's orbit will continue to be modified by its activity. Only after it moves away from the Sun, becomes largely inactive, and can be tracked for weeks or months will its orbit be known with some accuracy. Quite different from a short period comet like Halley, with its orbit regularly perturbed by Jupiter, and to a lesser degree, Saturn.
Of course, I'm talking about the chaotic motion of those Bill Haley dancers:
Swinging Mitch Feigenbaum and his partner.
Of course... eccentric to the point of being hyperbolic.
Chris

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