APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

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Expand view Topic review: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by neufer » Sun Feb 05, 2012 9:38 pm

bystander wrote:
We travel together, passengers on a little spaceship, dependent on its vulnerable reserves of air and soil;
all committed, for our safety, to its security and peace; preserved from annihilation only by the care,
the work and the love we give our fragile craft. ~ Adlai Stevenson ~ Geneva (09 July 1965)

Adlai Ewing Stevenson II (5 February 1900 – 14 July 1965)
Adlai Stevenson II: Death and Legacy wrote:
<<While walking in London with Marietta Tree through Grosvenor Square, Stevenson suffered a heart attack on the afternoon of July 14, 1965, and died later that day of heart failure at St George's Hospital. Marietta Tree recalled:

[After leaving the Embassy] [w]e walked around the neighborhood a little bit and where his house had been where he had lived with his family at the end of the War, there was now an apartment house and he said that makes me feel so old. Indeed, the whole walk made him feel very not so much nostalgic but so much older. As we were walking along the street he said do not walk quite so fast and do hold your head up Marietta. I was burrowing ahead trying to get to the park as quickly as possible and then the next thing I knew, I turned around and I saw he'd gone white, gray really, and he fell and his hand brushed me as he fell and he hit the pavement with the most terrible crack and I thought he'd fractured his skull.

Following memorial services at the United Nations General Assembly Hall (on July 19, 1965), and in Washington, D.C.; Springfield, Illinois; and Bloomington, Illinois, Stevenson was interred in the family plot in Evergreen Cemetery, Bloomington, Illinois. The funeral in Bloomington's Unitarian Church was attended by many national figures, including President Lyndon B. Johnson, Vice President Hubert Humphrey, and Supreme Court Chief Justice Earl Warren.>>

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by bystander » Sun Feb 05, 2012 8:48 pm

We travel together, passengers on a little spaceship, dependent on its vulnerable reserves of air and soil;
all committed, for our safety, to its security and peace; preserved from annihilation only by the care,
the work and the love we give our fragile craft. ~ Adlai Stevenson ~ Geneva (09 July 1965)

Adlai Ewing Stevenson II (5 February 1900 – 14 July 1965)

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by alter-ego » Sun Feb 05, 2012 1:34 am

Chris Peterson wrote:
This new image emphasizes the difference between an ordinary image from a satellite and a "blue marble" type image. Although both images were prepared from the same data set, the western hemisphere image was synthesized to give a view equivalent to what you'd see from 800 km high, while the eastern hemisphere image was synthesized to give a view equivalent to what you'd see from 13,000 km high. This ability to choose the viewpoint after the data is collected demonstrates the power of the blue marble approach.
This approach has certainly been proven valuable - just consider Google Earth, for example. The capability to merge simple visual aspects of control/display information detail and perspective (which most people easily relate to) with accessable, detailed scientific data (which most people don't relate to easily) is a real achievement. I believe we are currently living in a golden age of observational technology, and it's only going to get better!

On a separate more traditional note, I personally like the Eastern Hemisphere Blue Marble over the western version. At 13,000 km, its low-distortion mapping recreates a good satellite snapshot image. I feel more "at home" when looking at it. Maybe Art felt this way too based on his comments. To show a comparable view, a Google Earth image (at the same altitude) is overlayed below (move your cursor over it). The two images are almost indistinguishable geographically. However, distortion prevents this out-of-the box comparison from working well with the western hemisphere version.
Click to view full size image 1 or image 2
Lastly, I'd like to clarify one point: The Western Hemisphere Blue Marble is effectively viewed from an altidude 2x higher than discussed. Identifiable US and South American features require a minimum altitude of 820 miles, and because these features are not exactly on the horizon/limb (and therefore require a higher vantage point), I estimate a reasonable viewing altitude ≈1000 miles (1600 km).

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Chris Peterson » Sat Feb 04, 2012 3:39 pm

This new image emphasizes the difference between an ordinary image from a satellite and a "blue marble" type image. Although both images were prepared from the same data set, the western hemisphere image was synthesized to give a view equivalent to what you'd see from 800 km high, while the eastern hemisphere image was synthesized to give a view equivalent to what you'd see from 13,000 km high. This ability to choose the viewpoint after the data is collected demonstrates the power of the blue marble approach.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by bystander » Thu Feb 02, 2012 10:04 pm

Eastern Hemisphere - Blue Marble 2012
http://asterisk.apod.com/viewtopic.php?t=26868#p168591

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Chris Peterson » Wed Feb 01, 2012 8:23 pm

neufer wrote:The point of the APOD is that this is somehow a "Blue Marble Earth."
It isn't :!:
But it is. It's a synthesized image made from a much larger database of imagery. That is the meaning of "blue marble" in today's lingo.
Google Earth requires a considerable amount processing so that it has no clouds.
No it doesn't. There are clouds in Google imagery. And all they do is filter their particular blue marble dataset so that it contains only data with cloud cover below some threshold. That isn't real time processing.
This is a quasi-synoptic fisheye view of the Earth from NPP involving minimal processing.
This one particular image was synthesized from that viewpoint. And I'd bet it required almost identical routines to those used by Google Earth. In fact, I'd think there's a good chance they used the World Wind code, which was developed by NASA for displaying Blue Marble datasets (there are a number, encompassing different times of year and different weather).
No one (but you) cares that it didn't actually involve a fisheye lens camera.
You assume a lot about what other people care about!

If this were just a fisheye image made from yet another Earth observing satellite, it would be rather boring, I think. Ho hum... been there, done that. But satellites that are continuously adding high resolution imagery to a database which can be used to synthesize Earth views over time, space, and viewpoint... that's exciting!

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by neufer » Wed Feb 01, 2012 7:47 pm

Chris Peterson wrote:
neufer wrote:Rather....people SHOULD, indeed, think of it as a fisheye camera shot from a spacecraft a mere 500 miles above the earth.
I disagree. If this is how people see the image, they are entirely missing the point of the APOD!
The point of the APOD is that this is somehow a "Blue Marble Earth."
It isn't :!:
Chris Peterson wrote:
It's like looking at an image from Google Earth over your town, and thinking that Google Earth is just that image.
Google Earth requires a considerable amount processing so that it has no clouds.

This is a quasi-synoptic fisheye view of the Earth from NPP involving minimal processing.

No one (but you) cares that it didn't actually involve a fisheye lens camera.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Chris Peterson » Wed Feb 01, 2012 5:35 pm

neufer wrote:Rather....people SHOULD, indeed, think of it as a fisheye camera shot from a spacecraft a mere 500 miles above the earth.
I disagree. If this is how people see the image, they are entirely missing the point of the APOD!

It's like looking at an image from Google Earth over your town, and thinking that Google Earth is just that image.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by neufer » Wed Feb 01, 2012 5:28 pm

Chris Peterson wrote:
It's too easy for people to look at today's image and think it's just a shot made from one of the cameras on this spacecraft.
It's too easy for people to look at this image and think it's another yet stunning image made
from distant space such as from an Apollo mission or even a geostationary satellite like GOES.

Rather....people SHOULD, indeed, think of it as a fisheye camera shot from a spacecraft a mere 500 miles above the earth.

The small (6%) piece of Earth displayed is NOT very blue & NOT very marble like
and it should NOT have been presented as a "Blue Marble Earth" IMO.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by geckzilla » Wed Feb 01, 2012 3:01 pm

Brian O Dowd wrote:Is there images that show other parts of the world, like Europe, Asia, Africa, Australia, Antarctica, Arctic?
Sure... here's the whole world for you: http://earthobservatory.nasa.gov/IOTD/view.php?id=76674

Future images will probably end up here: http://npp.gsfc.nasa.gov/science/sciencecollection.html

I don't think there is a website that publishes the raw data the satellite is producing, though.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Brian O Dowd » Wed Feb 01, 2012 1:26 pm

Is there images that show other parts of the world, like Europe, Asia, Africa, Australia, Antarctica, Arctic?

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by neptunium » Tue Jan 31, 2012 12:17 am

deathfleer wrote:no more blue planets detected out there?
What about Kepler?

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by deathfleer » Tue Jan 31, 2012 12:14 am

no more blue planets detected out there?

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by EIhrke » Mon Jan 30, 2012 10:37 pm

Thanks for the link to Alan Bean's pages and the Apollo Lunar Surface Journals... which is accessed via the "Blue Marble Earth" link at the bottom of today's descriptive paragraph. I live for art and writing, and I was happy to spend time today inspired by Astronaut Bean's works. My favorites were "Hadley Rille", and "An Astronaut's Journey"- with Harrison "Jack" Schmitt's story.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Chris Peterson » Mon Jan 30, 2012 10:17 pm

neufer wrote:That decision was made to present a view of Earth just as
it would have been observed by a fisheye camera aboard NPP.
Understood. But the point is, it was a decision, unrelated to any physical constraints of the imaging system. I think it is important to emphasize that, since as a simple image, there is nothing extraordinary about today's APOD. What makes it special is that it was built from a much richer data set than any single image could represent.

It's too easy for people to look at today's image and think it's just a shot made from one of the cameras on this spacecraft.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by neufer » Mon Jan 30, 2012 10:09 pm

Chris Peterson wrote:
neufer wrote:
Only 12% of a hemisphere is observable from NPP's height. (See above.)
However, NPP's height isn't really relevant here, and does not define what we can or cannot see. That decision was made by whoever chose this particular projection for the data. No camera on NPP can provide a view like this at any time.
That decision was made to present a view of Earth just as
it would have been observed by a fisheye camera aboard NPP.

I.e., the horizon is exactly the same horizon that would be
observed by NPP if it's scanning cameras could actually see out to the horizon.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Flase » Mon Jan 30, 2012 10:02 pm

That's a point. There is a lot of cloud here. How do you control the cloud formations in this software? Even if you choose a date for your image data, these clouds would shift as the satellite takes its images. If these clouds are always in the same place, New Yorkers would be frustrated that they can only see a bit of long island poking out.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Flase » Mon Jan 30, 2012 9:47 pm

tcumming wrote:Still I was half expecting some hints of where major cities are. Maybe we aren't scarring the planet up quite as bad as it might seem when we are down in a metropolitan area that takes two hours to drive across.
LA, San Diego and Tijuana are quite visible as patches of grey concrete like tooth fillings. Mexico city is covered in cloud...

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Chris Peterson » Mon Jan 30, 2012 9:42 pm

neufer wrote:Only 12% of a hemisphere is observable from NPP's height. (See above.)
However, NPP's height isn't really relevant here, and does not define what we can or cannot see. That decision was made by whoever chose this particular projection for the data. No camera on NPP can provide a view like this at any time.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by neufer » Mon Jan 30, 2012 9:28 pm

MarvinSigal wrote:Excuse, but............
..............................it sure seems like the North American Continent is WAY out of proportion relative to the size of the sphere it is on.

Where's Greenland, and the rest of South America??????

AM I WRONG HERE????? :-)
You are not wrong...just late.

Only 12% of a hemisphere is observable from NPP's height. (See above.)

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by MarvinSigal » Mon Jan 30, 2012 9:10 pm

Excuse, but............
..............................it sure seems like the North American Continent is WAY out of proportion relative to the size of the sphere it is on.

AM I WRONG HERE??????

Where's Greenland, and the rest of South America??????

AM I WRONG HERE?????

:-)

Semihemidemi-Hemisphere

by neufer » Mon Jan 30, 2012 8:29 pm

neufer wrote:
lunartrax wrote:
This undeniably beautiful pic still seems to have been made with some distortion in size and shape.
The distortion comes from the fact that the perspective is presented as if from an NPP satellite a mere 824 kilometers above Earth.

At that altitude the edges of the Earth are about 62º off from Nadir (looking straight down).

Hence the NPP Blue Marble Earth should properly be viewed with a single eye about 2.4 inches above most computer screens.
drollere wrote:
it's worth mention that if the earth's diameter in relation to the span of the north american continent really were that small, it's probable that the earth's atmosphere would have long ago escaped and we'd be living on something resembling arid mars.
It would be closer to the size of Callisto actually.
  • Visible Fraction of Earth's Hemisphere as viewed
    from a given height of h is = h/(R+h)     where R = 6,371.0 km
--------------------------------------------------------------
Visible Fraction of Hemisphere observed:

12% : 824km Blue Marble Earth from Suomi NPP

85% : 35,786 km Blue Marble Earth from GOES

88% : 45,000 km Blue Marble Earth from Apollo 17

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by ricardelico » Mon Jan 30, 2012 7:20 pm

¡VIVA MÉXICO!

The 50,000 deaths due to bad UN XX-century drug regulation are too small to be seen in this beautiful image.

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by C0ppert0p » Mon Jan 30, 2012 7:18 pm

neufer wrote:
lunartrax wrote:
This undeniably beautiful pic still seems to have been made with some distortion in size and shape.
The distortion comes from the fact that the perspective is presented as if from an NPP satellite a mere 824 kilometers above Earth.

At that altitude the edges of the Earth are about 62º off from Nadir (looking straight down).

Hence the NPP Blue Marble Earth should properly be viewed with a single eye about 2.4 inches above most computer screens.
I tried viewing the image as you suggested. It was all blurry and my eye hurt after six seconds or so. Also, my forehead left a great grease print on the screen

Re: APOD: Blue Marble Earth from Suomi NPP (2012 Jan 30)

by Ann » Mon Jan 30, 2012 7:08 pm

I finally managed to look at the picture at full resolution. It is indeed a marvelous image. I take it that the aqua-green color of parts of the ocean means that the water is shallow here. Or maybe not? Maybe it just means erosion?

It is indeed amazing that we see so few signs of the great cities of the North American west coast. In Florida, we do see signs of the gridworks of civilization.

The various cloud formations that we see are indeed amazing, too.

I checked out my terrestrial globe at home, and I must agree that North and Central America are not as big in relation to the entire "face of the Earth" as they appear to be here.

But it is a truly fantastic and amazing image!

Ann

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