Comments and questions about the
APOD on the main view screen.
-
APOD Robot
- Otto Posterman
- Posts: 5599
- Joined: Fri Dec 04, 2009 3:27 am
Post
by APOD Robot » Wed Jan 29, 2020 5:07 am
Milky Way over Yellowstone
Explanation: The Milky Way was not created by an evaporating lake.
The pool of vivid blue water, about 10 meters across, is known as
Silex Spring and is located in
Yellowstone National Park in
Wyoming,
USA. Steam rises off
the spring, heated by a
magma chamber deep underneath known as the
Yellowstone hotspot. The steam blurs the image of
Jupiter, making it seem unusually large. Unrelated and far in the distance, the
central band of our
Milky Way Galaxy rises high overhead, a band lit by billions of stars. The featured picture is a 3-image panorama taken last August. If the
Yellowstone hotspot causes another
supervolcanic eruption as it did
640,000 years ago, a
large part of North America would be affected.
-
Guest
Post
by Guest » Wed Jan 29, 2020 5:50 am
Uh, Venus? How about Jupiter?
-
Ann
- 4725 Å
- Posts: 13858
- Joined: Sat May 29, 2010 5:33 am
Post
by Ann » Wed Jan 29, 2020 6:25 am
I was unable to even open the APOD page. Does anyone else have that problem?
Ann
Color Commentator
-
Ann
- 4725 Å
- Posts: 13858
- Joined: Sat May 29, 2010 5:33 am
Post
by Ann » Wed Jan 29, 2020 6:55 am
Okay, now I was able to open the APOD page!
I guess that today's APOD, even though it is a 3-image panorama, is not a composite using different exposure times for the sky and for the ground. I base my guess on the rather colorless appearance of the Milky Way, which suggests to me that this photograph was taken in a relatively "straightforward" way, possibly with no exposures through different filters.
We see no "drifting" of the sky, which I guess means that the camera was following the apparent "westward drift" of the sky. But we also see no sign that the sky and the ground are not stationary relatively to each other. Are we talking short exposures here? Is that possible, given the faintness of the Milky Way?
I am of course fascinated by the very blue color of the water in the pool, and the even bluer color of the steam rising out of it. What causes it?
Ann
Color Commentator
-
dipi
Post
by dipi » Wed Jan 29, 2020 8:10 am
I seem to have a problem with the TLS certificate of the APOD site.
There’s a http-to-https redirect, so I’m not even able to retrieve the unencrypted version.
-
orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Post
by orin stepanek » Wed Jan 29, 2020 11:40 am
We went there when the kids were little! It is a very interesting place; and worth visiting.
We weren't looking at the Milky Way however!
Orin
Smile today; tomorrow's another day!
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Wed Jan 29, 2020 2:43 pm
Ann wrote: ↑Wed Jan 29, 2020 6:55 am
<<I am of course fascinated by the very blue color of the water in the pool, and
the even bluer color of the steam rising out of it. What causes it?>>
Purity Of Essence
https://en.wikipedia.org/wiki/Dr._Strangelove wrote:
General Buck Turgidson (George C. Scott):
"So let's get going, there's no other choice. God willing, we will prevail, in peace and freedom from fear, and in true health, through the purity and essence of our natural... fluids. God bless you all." And [then Brigadier General Jack D. Ripper (Sterling Hayden)] hung up. [Pause as he realizes the implications of General Ripper's words]
Uh, we're... still trying to figure out the meaning of that last phrase, sir.
https://en.wikipedia.org/wiki/Color_of_water wrote:
<<While relatively small quantities of water appear to be colorless,
pure water has a slight blue color that becomes a deeper blue as the thickness of the observed sample increases. The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light.
The water molecule has three fundamental modes of vibration. Two stretching vibrations of the O-H bonds in the gaseous state of water occur at [infrared frequencies:] v1 = 3650 cm−1 and v3 = 3755 cm−1. Absorption due to these vibrations occurs in the infrared region of the spectrum. The absorption in the visible spectrum is due mainly to the harmonic v1 + 3v3 = 14,318 cm−1, which is equivalent to a wavelength of 698 nm. In liquid state at 20°C these vibrations are red-shifted due to hydrogen bonding, resulting in red absorption at 740 nm, other harmonics such as v1 + 3v3 giving red absorption at 660 nm.
The intrinsic colour of liquid water may be demonstrated by looking at a white light source through a long pipe that is filled with purified water and closed at both ends with a transparent window. The light turquoise blue colour is caused by weak absorption in the red part of the visible spectrum. Absorption intensity decreases markedly with each successive overtone, resulting in very weak absorption for the third overtone. For this reason,
the pipe needs to have a length of a meter or more and the water must be purified by microfiltration to remove any particles that could produce Mie scattering.>>
https://en.wikipedia.org/wiki/Grand_Prismatic_Spring wrote:
<<The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world, after Frying Pan Lake in New Zealand and Boiling Lake in Dominica. Its colors match most of those seen in the rainbow dispersion of white light by an optical prism: red, orange, yellow, green, and blue.
The vivid colors in the spring are the result of microbial mats around the edges of the mineral-rich water. The mats produce colors ranging from green to red; the amount of color in the microbial mats depends on the ratio of chlorophyll to carotenoids and on the temperature gradient in the runoff. In the summer, the mats tend to be orange and red, whereas in the winter the mats are usually dark green.
The center of the pool is sterile due to extreme heat. The deep blue color of the water in the center of the pool results from the intrinsic blue color of water. The effect is strongest in the center of the spring, because of its sterility and depth. The spring is approximately 110 m in diameter and is 50 m deep.>>
APOD Robot wrote: ↑Wed Aug 27, 2014 4:08 am
Explanation: The Milky Way was not created by an evaporating lake. The colorful pool of water, about 10 meters across, is known as
Silex Spring and is located in
Yellowstone National Park in
Wyoming,
USA. Illuminated artificially, the colors are caused by layers of
bacteria that grow in the
hot spring. Steam rises off
the spring, heated by a
magma chamber deep underneath known as the
Yellowstone hotspot. Unrelated and far in the distance, the
central band of our
Milky Way Galaxy arches high overhead, a band lit by billions of stars. The
above picture is a 16-image panorama taken late last month. If the Yellowstone hotspot causes another supervolcanic eruption as it did
640,000 years ago, a
large part of North America would be affected.
Art Neuendorffer
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Wed Jan 29, 2020 2:49 pm
orin stepanek wrote: ↑Wed Jan 29, 2020 11:40 am
We went there when the kids were little!
It is a very interesting place; and worth visiting.
All are welcome
Art Neuendorffer
-
wenbin
- Asternaut
- Posts: 1
- Joined: Wed Jan 29, 2020 4:50 am
Post
by wenbin » Wed Jan 29, 2020 2:54 pm
great!
-
Ann
- 4725 Å
- Posts: 13858
- Joined: Sat May 29, 2010 5:33 am
Post
by Ann » Wed Jan 29, 2020 4:11 pm
neufer wrote: ↑Wed Jan 29, 2020 2:43 pm
https://en.wikipedia.org/wiki/Dr._Strangelove wrote:
General Buck Turgidson (George C. Scott):
"So let's get going, there's no other choice. God willing, we will prevail, in peace and freedom from fear, and in true health, through the purity and essence of our natural... fluids. God bless you all." And [then Brigadier General Jack D. Ripper (Sterling Hayden)] hung up. [Pause as he realizes the implications of General Ripper's words]
Uh, we're... still trying to figure out the meaning of that last phrase, sir.
Brigadier General Jack D. Strangelove Ripper????
https://en.wikipedia.org/wiki/Color_of_water wrote:
<<While relatively small quantities of water appear to be colorless,
pure water has a slight blue color that becomes a deeper blue as the thickness of the observed sample increases. The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light.
The water molecule has three fundamental modes of vibration. Two stretching vibrations of the O-H bonds in the gaseous state of water occur at [infrared frequencies:] v1 = 3650 cm−1 and v3 = 3755 cm−1. Absorption due to these vibrations occurs in the infrared region of the spectrum. The absorption in the visible spectrum is due mainly to the harmonic v1 + 3v3 = 14,318 cm−1, which is equivalent to a wavelength of 698 nm. In liquid state at 20°C these vibrations are red-shifted due to hydrogen bonding, resulting in red absorption at 740 nm, other harmonics such as v1 + 3v3 giving red absorption at 660 nm.
The intrinsic colour of liquid water may be demonstrated by looking at a white light source through a long pipe that is filled with purified water and closed at both ends with a transparent window. The light turquoise blue colour is caused by weak absorption in the red part of the visible spectrum. Absorption intensity decreases markedly with each successive overtone, resulting in very weak absorption for the third overtone. For this reason,
the pipe needs to have a length of a meter or more and the water must be purified by microfiltration to remove any particles that could produce Mie scattering.>>
https://en.wikipedia.org/wiki/Grand_Prismatic_Spring wrote:
<<The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world, after Frying Pan Lake in New Zealand and Boiling Lake in Dominica. Its colors match most of those seen in the rainbow dispersion of white light by an optical prism: red, orange, yellow, green, and blue.
The vivid colors in the spring are the result of microbial mats around the edges of the mineral-rich water. The mats produce colors ranging from green to red; the amount of color in the microbial mats depends on the ratio of chlorophyll to carotenoids and on the temperature gradient in the runoff. In the summer, the mats tend to be orange and red, whereas in the winter the mats are usually dark green.
The center of the pool is sterile due to extreme heat. The deep blue color of the water in the center of the pool results from the intrinsic blue color of water. The effect is strongest in the center of the spring, because of its sterility and depth. The spring is approximately 110 m in diameter and is 50 m deep.>>
APOD Robot wrote: ↑Wed Aug 27, 2014 4:08 am
Explanation: The Milky Way was not created by an evaporating lake. The colorful pool of water, about 10 meters across, is known as
Silex Spring and is located in
Yellowstone National Park in
Wyoming,
USA. Illuminated artificially, the colors are caused by layers of
bacteria that grow in the
hot spring. Steam rises off
the spring, heated by a
magma chamber deep underneath known as the
Yellowstone hotspot. Unrelated and far in the distance, the
central band of our
Milky Way Galaxy arches high overhead, a band lit by billions of stars. The
above picture is a 16-image panorama taken late last month. If the Yellowstone hotspot causes another supervolcanic eruption as it did
640,000 years ago, a
large part of North America would be affected.
Thanks, Art, that's so interesting! Note , however, that
in that other APOD, the steam rising from the pool is not blue.
Color Commentator
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Wed Jan 29, 2020 4:34 pm
Ann wrote: ↑Wed Jan 29, 2020 4:11 pm
Thanks, Art, that's so interesting! Note , however, that
in that other APOD, the steam rising from the pool is not blue.
Steam color is
Mie scattering of whatever the illumination color was.
Perhaps, the artificial steam illumination in today's APOD was bluer and/or made bluer by being directed into the pool itself.
Art Neuendorffer
-
Cousin Ricky
- Science Officer
- Posts: 468
- Joined: Mon Aug 26, 2013 4:08 pm
- Location: St. Thomas, U.S. Virgin Islands (+18.3, -64.9)
Post
by Cousin Ricky » Wed Jan 29, 2020 4:39 pm
Ann wrote: ↑Wed Jan 29, 2020 6:25 am
I was unable to even open the APOD page. Does anyone else have that problem?
I cannot connect either. But the image is posted on
their Facebook page.
-
Ann
- 4725 Å
- Posts: 13858
- Joined: Sat May 29, 2010 5:33 am
Post
by Ann » Wed Jan 29, 2020 6:02 pm
neufer wrote: ↑Wed Jan 29, 2020 4:34 pm
Ann wrote: ↑Wed Jan 29, 2020 4:11 pm
Thanks, Art, that's so interesting! Note , however, that
in that other APOD, the steam rising from the pool is not blue.
Steam color is
Mie scattering of whatever the illumination color was.
Perhaps, the
artificial steam illumination in today's APOD was bluer and/or made bluer by being directed into the pool itself.
It was the steam in the APOD of August 27, 2014, that was artificially illuminated!
Nothing is said in the caption of today's APOD that the steam was artificially illuminated.
You mean that the artificial illumination in today's APOD is so obvious that it goes without saying?
Ann
Color Commentator
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Wed Jan 29, 2020 6:09 pm
Ann wrote: ↑Wed Jan 29, 2020 6:02 pm
Nothing is said in the caption of today's APOD that the steam was artificially illuminated.
You mean that the artificial illumination in today's APOD is so obvious that it goes without saying?
- That's Mie Artificial illumination on the issue.
Art Neuendorffer
-
Guest
Post
by Guest » Wed Jan 29, 2020 6:59 pm
Hey,
that should be Jupiter instead of Venus, no?
Dom
Belgium
-
Ann
- 4725 Å
- Posts: 13858
- Joined: Sat May 29, 2010 5:33 am
Post
by Ann » Wed Jan 29, 2020 7:01 pm
neufer wrote: ↑Wed Jan 29, 2020 6:09 pm
Ann wrote: ↑Wed Jan 29, 2020 6:02 pm
Nothing is said in the caption of today's APOD that the steam was artificially illuminated.
You mean that the artificial illumination in today's APOD is so obvious that it goes without saying?
- That's Mie Artificial illumination on the issue.
Color Commentator
-
RJN
- Baffled Boffin
- Posts: 1674
- Joined: Sat Jul 24, 2004 1:58 pm
- Location: Michigan Tech
Post
by RJN » Wed Jan 29, 2020 8:23 pm
Guest wrote: ↑Wed Jan 29, 2020 5:50 am
Uh, Venus? How about Jupiter?
Yes, the planet is Jupiter. My bad. This has now been fixed on the main NASA APOD. Apologies. - RJN
-
Deathfleer
Post
by Deathfleer » Thu Jan 30, 2020 12:33 am
Very beautiful. The universe is very very big. SubhanaLlah.
-
ta152h0
- Schooled
- Posts: 1399
- Joined: Mon Aug 29, 2005 12:46 am
- Location: Auburn, Washington, USA
Post
by ta152h0 » Thu Jan 30, 2020 2:28 am
Out of curiosity, do vacuum tubes work in space without the glass enclosure? I just broke a 5u4 but didn't scratch the insides.
Wolf Kotenberg
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Thu Jan 30, 2020 3:43 am
ta152h0 wrote: ↑Thu Jan 30, 2020 2:28 am
Out of curiosity, do vacuum tubes work in space without the glass enclosure? I just broke a 5u4 but didn't scratch the insides.
Why would most vacuum tubes care about how large their "glass enclosures" were?
Art Neuendorffer
-
Chris Peterson
- Abominable Snowman
- Posts: 18607
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
Post
by Chris Peterson » Thu Jan 30, 2020 3:01 pm
ta152h0 wrote: ↑Thu Jan 30, 2020 2:28 am
Out of curiosity, do vacuum tubes work in space without the glass enclosure? I just broke a 5u4 but didn't scratch the insides.
The tubes themselves would work. The circuits they are part of would generally not (or not as intended), as the glass enclosure doesn't just maintain a vacuum around the elements, but it also acts as an insulator to prevent current from flowing between elements of different tubes or other parts of the circuit.
-
ta152h0
- Schooled
- Posts: 1399
- Joined: Mon Aug 29, 2005 12:46 am
- Location: Auburn, Washington, USA
Post
by ta152h0 » Thu Jan 30, 2020 6:10 pm
so throw away the 5u4, right?!
Wolf Kotenberg
-
Chris Peterson
- Abominable Snowman
- Posts: 18607
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
Post
by Chris Peterson » Thu Jan 30, 2020 6:24 pm
ta152h0 wrote: ↑Thu Jan 30, 2020 6:10 pm
so throw away the 5u4, right?!
Replace it with a solid state device. Tubes have almost no place in modern electronics.
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Thu Jan 30, 2020 9:01 pm
Chris Peterson wrote: ↑Thu Jan 30, 2020 6:24 pm
ta152h0 wrote: ↑Thu Jan 30, 2020 6:10 pm
so throw away the 5u4, right?!
Replace it with a solid state device. Tubes have almost no place in modern electronics.
At least, lug that tube down to your local defunct drugstore (e.g., Peoples, Adams, Happy Harry's, Eckerd, Hook's, Big B, G.O. Guy, Gray, Brooks, Revco, K&B, etc.) and test that sucker
Art Neuendorffer