Colour pics of New York City in the '40s Ok, bear with me...
Go here:
http://webapp1.dlib.indiana.edu/cushman/search/index.jsp
put in this string and search:
country:"United States" AND state:"New York" AND city:"New York" NOT paintings
These are super cool. It really captures a flavour that is tough to put into words (well, it's tough at 2:30am).
8 comments Speaking of colour photos, how come NASA sent this billion-dollar space probe to Mars, but gave it a black-and-white camera?
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There are three pairs of cameras on the Spirit. These first images are from the black and white Navcam. There is another pair (also, b/w) called the Hazcam mounted lower on the rover to watch for obstacles. The colour CCD is the Pancam and I assume they wanted the first pictures quickly so only sent the b/w pics first. The colour ones can't be too far behind.
If I remember right, Opportunity should land on the opposite side of Mars later this month. | | |
I've got a follow-up question. Why can't photos be sent back at the speed of light? Even from Mars, that would only take a minute or two at most (making the chinsy, black-and-white camera unnecessary).
What is the technology that one would use to send images back from deep space? Anyone? | | |
well, that's a pretty complicated topic. Here's the 5 second summary:
-A picture is a grid of dots.
-Each dot can have information about it (colour requires knowing how much red, blue and green, b/w only requires a scale number from 1-100 with 1 as white and 100 as black)
-the more dots in the grid the better the picture (think of a picture that is only 2x2 dots vs a pic that is 100x100 dots). These dots are called pixels.
- a 2x2 pic has only 4 pixels, a 100x100 pic has 10,000 pixels
-for b/w 100x100 pic, you need to send 10,000 numbers from 1-100. for a colour pic you need to send 3x10,000 numbers from 1-100.
Now, how to send a signal from mars to earth (over- simplified):
-send a radio beam from surface of mars to orbiting satellite (you can't send one straight to earth or you'd lose signal as it rotated out of view, you can always keep a satellite in view).
-Have the satellite relay the info to a series of antenna on earth (they're positioned around earth [spain, australia and usa have the biggest centers i think] so that even as we rotate we can always pick it up).
-Have the strength of the beam divisible from 1-100 in increments of 1 sec. So to send the series 2,45,63, the beam has a strength of 2 for second #1, 45 for second #2 and 63 for second #3. There, you've now sent 3 b/w pixels or one colour pixel. It took 3 seconds.
Of course, this is done much faster and using more sophisticated methods but that's the general idea. So while the info is reaching us at the speed of light, there is only so much info per sec that can be squeezed into a beam of information.
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For anyone who hasn't fallen asleep yet:
http://deepspace.jpl.nasa.gov/dsn/images/album/dsn71.jpg
Apparently you can set your 2018 alarms to go off to remind yourself that people will be on Mars... | | |
I like the hat pictures:
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When I saw the hat photo, I asked myself why people don't dress that snazzily these days. Then, I saw the caption. They are hobos!
Some things have changed in New York.
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| many people associate hobos as drunking stret scum and its good to see that these derrogatorie terms dont get these hobos down. | | |
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