APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

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APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by APOD Robot » Wed Jan 12, 2022 5:06 am

Image Comet Leonard Closeup from Australia

Explanation: What does Comet Leonard look like up close? Although we can't go there, imaging the comet's coma and inner tails through a small telescope gives us a good idea. As the name implies, the ion tail is made of ionized gas -- gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun's complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet's nucleus accounts for the tail's complex structure. Following the wind, structure in Comet Leonard's tail can be seen to move outward from the Sun even alter its wavy appearance over time. The blue color of the ion tail is dominated by recombining carbon monoxide molecules, while the green color of the coma surrounding the head of the comet is created mostly by a slight amount of recombining diatomic carbon molecules. Diatomic carbon is destroyed by sunlight in about 50 hours -- which is why its green glow does not make it far into the ion tail. The featured imagae was taken on January 2 from Siding Spring Observatory in Australia. Comet Leonard, presently best viewed from Earth's Southern Hemisphere, has rounded the Sun and is now headed out of the Solar System.

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Ann
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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by Ann » Wed Jan 12, 2022 5:37 am

Nice image!

Note that the blue gas tail seems to be superposed onto the yellow dust tail, i.e., one of these tails is seen directly in front of the other from our position. Normally, the two tails of a comet are seen separately.

phot-mar14-hbs-2[1].jpg
Comet Hale-Bopp, with two tails seen. Image: ESO/E. Slawik

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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by orin stepanek » Wed Jan 12, 2022 12:35 pm

When a comet can no longer produce a tail; does it become an asteroid?
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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by Chris Peterson » Wed Jan 12, 2022 2:02 pm

orin stepanek wrote:
Wed Jan 12, 2022 12:35 pm
When a comet can no longer produce a tail; does it become an asteroid?
The terminology isn't rigorously defined. In common usage, an asteroid is any rocky body above a certain size but not meeting the definition of a planet. There are almost certainly bodies we identify as asteroids that started out as comets. But if there's a good reason to think a rocky body that is devoid of volatiles started out as a comet, we're inclined to refer to it as an extinct comet (or some similar terminology). The distinction can be important given the presumably different history of formation and evolution of comets and asteroids.
Chris

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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by Eclectic Man » Wed Jan 12, 2022 10:30 pm

Chris Peterson wrote:
Wed Jan 12, 2022 2:02 pm
orin stepanek wrote:
Wed Jan 12, 2022 12:35 pm
When a comet can no longer produce a tail; does it become an asteroid?
The terminology isn't rigorously defined. In common usage, an asteroid is any rocky body above a certain size but not meeting the definition of a planet. There are almost certainly bodies we identify as asteroids that started out as comets. But if there's a good reason to think a rocky body that is devoid of volatiles started out as a comet, we're inclined to refer to it as an extinct comet (or some similar terminology). The distinction can be important given the presumably different history of formation and evolution of comets and asteroids.
Asteroid 248370 appears to also be a comet:

http://www.sci-news.com/astronomy/main- ... 10137.html

"(248370) 2005 QN137 is the eighth main-belt asteroid, out of more than half a million asteroids in the main belt, confirmed to not only be active, but to have been active on more than one occasion.

248370) 2005 QN173 was discovered to be active on July 7, 2021 in data obtained by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) survey telescope.

On that date, the object was at a heliocentric distance of 2.39 AU (astronomical units), and exhibited a thin, straight dust tail.

“This behavior strongly indicates that its activity is due to the sublimation of icy material,” said Dr. Henry Hsieh, senior scientist at the Planetary Science Institute.

“As such, it is considered a so-called main-belt comet, and is one of just about 20 objects that have currently been confirmed or are suspected to be main-belt comets, including some that have only been observed to be active once so far.”

“2005 QN173 can be thought of as both an asteroid and a comet, or more specifically, a main-belt asteroid that has just recently been recognized to also be a comet.”
"

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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by Chris Peterson » Wed Jan 12, 2022 11:24 pm

Eclectic Man wrote:
Wed Jan 12, 2022 10:30 pm
Chris Peterson wrote:
Wed Jan 12, 2022 2:02 pm
orin stepanek wrote:
Wed Jan 12, 2022 12:35 pm
When a comet can no longer produce a tail; does it become an asteroid?
The terminology isn't rigorously defined. In common usage, an asteroid is any rocky body above a certain size but not meeting the definition of a planet. There are almost certainly bodies we identify as asteroids that started out as comets. But if there's a good reason to think a rocky body that is devoid of volatiles started out as a comet, we're inclined to refer to it as an extinct comet (or some similar terminology). The distinction can be important given the presumably different history of formation and evolution of comets and asteroids.
Asteroid 248370 appears to also be a comet:

http://www.sci-news.com/astronomy/main- ... 10137.html

"(248370) 2005 QN137 is the eighth main-belt asteroid, out of more than half a million asteroids in the main belt, confirmed to not only be active, but to have been active on more than one occasion.

248370) 2005 QN173 was discovered to be active on July 7, 2021 in data obtained by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) survey telescope.

On that date, the object was at a heliocentric distance of 2.39 AU (astronomical units), and exhibited a thin, straight dust tail.

“This behavior strongly indicates that its activity is due to the sublimation of icy material,” said Dr. Henry Hsieh, senior scientist at the Planetary Science Institute.

“As such, it is considered a so-called main-belt comet, and is one of just about 20 objects that have currently been confirmed or are suspected to be main-belt comets, including some that have only been observed to be active once so far.”

“2005 QN173 can be thought of as both an asteroid and a comet, or more specifically, a main-belt asteroid that has just recently been recognized to also be a comet.”
"
We also talk about "active asteroids", which aren't necessarily the same as comets, depending on formation and origin. There's a lot of overlap in these things.
Chris

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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by Fred the Cat » Thu Jan 13, 2022 12:47 am

Just as long as they aren't too " closeup" to Australia.

We don't need any more thawing. :no:
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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by johnnydeep » Thu Jan 13, 2022 7:10 pm

Ann wrote:
Wed Jan 12, 2022 5:37 am
Nice image!

Note that the blue gas tail seems to be superposed onto the yellow dust tail, i.e., one of these tails is seen directly in front of the other from our position. Normally, the two tails of a comet are seen separately.

phot-mar14-hbs-2[1].jpg
Comet Hale-Bopp, with two tails seen. Image: ESO/E. Slawik

Ann
Hmm, so are my eyes playing tricks on me or does the combination of the tails appear more pink than blue? At least, farther away from the center and end.
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Re: APOD: Comet Leonard Closeup from Australia (2022 Jan 12)

Post by Ann » Thu Jan 13, 2022 7:48 pm

johnnydeep wrote:
Thu Jan 13, 2022 7:10 pm

Hmm, so are my eyes playing tricks on me or does the combination of the tails appear more pink than blue? At least, farther away from the center and end.
I'd say the pink color of the dust tail in this image is a quirk of this particular image. I googled "Comet Leonard" and found several other images of the comet, none of which showed the comet with a pink tail.

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