APOD: Stickney Crater (2018 May 05)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 3182
Joined: Fri Dec 04, 2009 3:27 am

APOD: Stickney Crater (2018 May 05)

Post by APOD Robot » Sat May 05, 2018 4:05 am

Image Stickney Crater

Explanation: Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons in 1877. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon. This stunning, enhanced-color image of Stickney and surroundings was recorded by the HiRISE camera onboard the Mars Reconnaissance Orbiter as it passed within some six thousand kilometers of Phobos in March of 2008. Even though the surface gravity of asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material slid down inside the crater walls over time. Light bluish regions near the crater's rim could indicate a relatively freshly exposed surface. The origin of the curious grooves along the surface is mysterious but may be related to the crater-forming impact.

<< Previous APOD This Day in APOD Next APOD >>

Boomer12k
:---[===] *
Posts: 2220
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Stickney Crater (2018 May 05)

Post by Boomer12k » Sat May 05, 2018 8:15 am

Wonderful Image...and intriguing...

:---[===] *

User avatar
orin stepanek
Plutopian
Posts: 4540
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: Stickney Crater (2018 May 05)

Post by orin stepanek » Sat May 05, 2018 10:45 am

Wondering the composition of the Silvery material? :shock:
Orin

Smile today; tomorrow's another day!

User avatar
Ann
4725 Å
Posts: 8799
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Stickney Crater (2018 May 05)

Post by Ann » Sat May 05, 2018 11:30 am

orin stepanek wrote:
Sat May 05, 2018 10:45 am
Wondering the composition of the Silvery material? :shock:
(Relatively) fresh ice?

Ann
Color Commentator

barobins@telusplanet.net

Re: APOD: Stickney Crater (2018 May 05)

Post by barobins@telusplanet.net » Sat May 05, 2018 12:43 pm

What would happen to Earth's moon if a large object similar to what hit Phobos hit our Moon?? Would that cause tidal waves on Earth?? Would we be in the path of any debris that would be dislodged from the Moon? IF we have a colony on the Moon would we have time to get them off and out of danger??

heehaw

Re: APOD: Stickney Crater (2018 May 05)

Post by heehaw » Sat May 05, 2018 1:51 pm

barobins@telusplanet.net wrote:
Sat May 05, 2018 12:43 pm
What would happen to Earth's moon if a large object similar to what hit Phobos hit our Moon?? Would that cause tidal waves on Earth?? Would we be in the path of any debris that would be dislodged from the Moon? IF we have a colony on the Moon would we have time to get them off and out of danger??
An academic question, in your lifetime and mine: https://en.wikipedia.org/wiki/Sentry_(m ... ng_system)

User avatar
Chris Peterson
Abominable Snowman
Posts: 13757
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Stickney Crater (2018 May 05)

Post by Chris Peterson » Sat May 05, 2018 2:07 pm

orin stepanek wrote:
Sat May 05, 2018 10:45 am
Wondering the composition of the Silvery material? :shock:
The surface of Phobos consists of rock- primarily silicates. There may be ice in the interior, but there is no ice on the surface and the regolith is not hydrated. The reflectivity of the surface material is very low- Phobos is really a lump of coal in appearance. The outer few meters is weathered regolith, which is naturally dark. Anything which exposes underlying material will create lighter areas. That includes impacts and landslides. The image has been enhanced so that we can see detail and structure. The natural albedo range, which is low, has been stretched to approximately 100%. In other words, what you're seeing as "silvery" may be as dark as fresh asphalt in reality.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Chris Peterson
Abominable Snowman
Posts: 13757
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Stickney Crater (2018 May 05)

Post by Chris Peterson » Sat May 05, 2018 2:10 pm

barobins@telusplanet.net wrote:
Sat May 05, 2018 12:43 pm
What would happen to Earth's moon if a large object similar to what hit Phobos hit our Moon?? Would that cause tidal waves on Earth?? Would we be in the path of any debris that would be dislodged from the Moon? IF we have a colony on the Moon would we have time to get them off and out of danger??
Keep in mind that the object which hit Phobos only created a crater 9 km across. Such objects hit the Moon every few thousand years. That has no effect on Earth at all. A collision of that size might produce a few lunar meteorites on Earth. No tidal effects, no impacts. Nor would it cause any problems for a colony on the Moon unless the impact was very close to that colony.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Rick357
Asternaut
Posts: 1
Joined: Sat May 05, 2018 2:18 pm

Re: APOD: Stickney Crater (2018 May 05)

Post by Rick357 » Sat May 05, 2018 2:23 pm

Ablation. The 'moon' went through atmosphere oriented so the left side was exposed to the atmospheric erosion - the crater rim is significantly rounded with trailing tendrils of ablative channels, and the right side was protected in the lee of direction of the motion - the crater rim is sharp and pristine looking.

User avatar
Chris Peterson
Abominable Snowman
Posts: 13757
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Stickney Crater (2018 May 05)

Post by Chris Peterson » Sat May 05, 2018 2:25 pm

Rick357 wrote:
Sat May 05, 2018 2:23 pm
Ablation. The 'moon' went through atmosphere oriented so the left side was exposed to the atmospheric erosion - the crater rim is significantly rounded with trailing tendrils of ablative channels, and the right side was protected in the lee of direction of the motion - the crater rim is sharp and pristine looking.
Not likely. This is not a solid body, but some sort of rubble pile with a few meters of fine powder on its surface. And it couldn't have encountered an atmosphere in the last tens of millions of years or longer, meaning most evidence of such an encounter would have long since weathered away.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 14957
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Stickney Crater (2018 May 05)

Post by neufer » Sat May 05, 2018 4:50 pm

http://maia.usno.navy.mil/women_history/hall.html wrote: The Contributions of Women to the United States Naval Observatory: The Early Years.

<<One of the greatest obstacles to professional success for a woman in science in the late 19th and early 20th century, was the pressure put on her by society. Ancient folklore and even the current "scientific" research concluded that women should avoid education. One such "scientific study" conducted by Dr. Edward Clark of Harvard in the late nineteenth century concluded that the intellectual development of a woman would proceed only at the sacrifice of her reproductive organs. If a woman did pursue an education and a career, then married, she was expected to resign her position to become a full-time wife and mother. If an educated woman married a man in the scientific community she was expected to resign her position in order to assist her husband in his career. In fact, the career of a male scientist was usually greatly enhanced by assistance from his wife in the same field, although the woman received little or no credit and compensation for their contributions.

A prime example of this occurred at the USNO with one of our most prominent astronomers, Asaph Hall who discovered the two moons of Mars. Hall was fortunate enough to marry Chloe Angeline Stickney, a woman who had been his mathematics professor in college. During their days together as teacher and student, Hall and his classmates would devise questions and problems that they were convinced Miss Stickney could not solve, yet she never failed to solve them. Angeline Stickney gave up her career to marry Asaph Hall, she took an active interest in her husband's career. In fact it was she who petitioned Captain Gilliss via letter to promote her husband to Professor of Mathematics. Captain Gilliss embraced this suggestion, replying to Mrs. Hall that she could hereafter address her husband as "Professor" Hall. Asaph Hall himself acknowledged the contribution his wife made to his success in astronomy when speaking of his discovery of Demios and Phobos; "The chance of finding a satellite appeared to be very slight, so that I might have abandoned the search had it not been for the encouragement of my wife." However Mr. Hall drew the line when Mrs. Hall demanded a man's wage while she assisted her husband in his computations, when he refused her, she refused to continue that work.>>
Art Neuendorffer

User avatar
Cousin Ricky
Science Officer
Posts: 217
Joined: Mon Aug 26, 2013 4:08 pm
Location: St. Thomas, U.S. Virgin Islands (+18.3, -64.9)

Re: APOD: Stickney Crater (2018 May 05)

Post by Cousin Ricky » Sat May 05, 2018 5:30 pm

APOD Robot wrote:
Sat May 05, 2018 4:05 am
The origin of the curious grooves along the surface is mysterious but may be related to the crater-forming impact.
The grooves do not appear to radiate from Stickney, however; at least not in this photo. Another hypothesis that I’m aware of is that Phobos is getting uncomfortably close to the Roche limit, and the grooves are an effect of tidal stress. Probably more likely is that, since the radiant coincides with Phobos’ leading apex, they are due to multiple smaller impacts over the eons [citation].

JOHN MIOTTEL

Re: APOD: Stickney Crater (2018 May 05)

Post by JOHN MIOTTEL » Sat May 05, 2018 5:40 pm

I finally asked myself what caused the craters - there is no residual impact object like a big rock - I guess the impact object must be ice chunks ??

Crash

User avatar
neufer
Vacationer at Tralfamadore
Posts: 14957
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

LIMTOC: The Stickey Crater

Post by neufer » Sat May 05, 2018 5:58 pm

https://en.wikipedia.org/wiki/Stickney_(crater) wrote:
<<Stickney has a smaller crater within it, about 2 km in diameter, resulting from a later impact.
In 2006 it was given the name LIMTOC, after a character in Gulliver's Travels.

..................................................................................................................
. Gulliver's Travels, by Jonathan Swift Chapter VII.

<<This lord, in conjunction with Flimnap the high-treasurer, whose enmity against you is notorious on account of his lady, LIMTOC the general, Lalcon the chamberlain, and Balmuff the grand justiciary, have prepared articles of impeachment against you, for treason and other capital crimes.”

“’Articles of Impeachment against QUINBUS FLESTRIN, (the Man-Mountain.)

ARTICLE I: “’Whereas, by a statute made in the reign of his imperial majesty Calin Deffar Plune, it is enacted, that, whoever shall make water within the precincts of the royal palace, shall be liable to the pains and penalties of high-treason; notwithstanding, the said Quinbus Flestrin, in open breach of the said law, under colour of extinguishing the fire kindled in the apartment of his majesty’s most dear imperial consort, did maliciously, traitorously, and devilishly, by discharge of his urine, put out the said fire kindled in the said apartment, lying and being within the precincts of the said royal palace, against the statute in that case provided, etc. a.>>
Art Neuendorffer