APOD: Days in the Sun (2012 Jan 21)

[APOD Robot]

Days in the Sun

Explanation: From solstice to solstice, this six month long exposure compresses time from the 21st of June till the 21st of December, 2011, into a single point of view. Dubbed a solargraph, the unconventional picture was recorded with a pinhole camera made from a drink can lined with a piece of photographic paper. Fixed to a single spot for the entire exposure, the simple camera continuously records the Sun's path each day as a glowing trail burned into the photosensitive paper. In this case, the spot was chosen to look out over the domes and radio telescope of the University of Hertfordshire's Bayfordbury Observatory. Dark gaps in the daily arcs are caused by cloud cover, whereas continuous bright tracks record glorious spells of sunny weather. Of course, in June, the Sun trails begin higher at the northern hemisphere's summer solstice. The trails sink lower in the sky as December's winter solstice approaches. Last year's autumn was one of the balmiest on record in the UK, as the many bright arcs in the lower part of this picture testify.

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[Ann]

I noticed this image in the Recent Submissions thread and was impressed at the statuary beauty of it, as if this progression of arcs had a tangible presence, sculpted in marble. But I didn't bother to find out more about the picture or how it was made. Now that I have learnt that this is an unbroken six months' exposure taken with the kind of camera that Leonardo da Vinci could have used - except that he didn't have any photographic paper - I'm more impressed than ever. How clever! How simple! How beautiful!

The photographer, Regina Valkenborgh, is not an astronomer but an artist using pin-hole photography to explore the possibilities of this ancient technique to make records of reality.

How smart. How simple. How beautiful.

Ann

[bactame]

The image is neat as are those similar ones posted in the past. This one though gives you a good idea about the weather at that location over the year. Each township could almost generate their own image to give the public an idea of how nice the weather has or hasn't been over the year.

[John Carswell]

I want to make a similar image from Latitude 31'04" Longitude 81'26". Can anyone give me details so I can make a beer can camera?

[starstruck]

What a brilliantly simple, but effective idea! I love this, thanks APOD. It's the sort of project every school child could be given the opportunity to try out, using materials that cost next to nothing. Things like this can really capture the imagination.

John, try this web page . .
http://www.pinholephotography.org/Solar ... ns%202.htm
. . it's a link off today's APOD description entitled 'a pinhole camera made from'.

I'm going to give this a try here too, I know just the spot I could place one of these unobtrusive little pinhole cams.

[orin stepanek]

It is amazing how much change there is from a short Winter day to a long Summer one; and here you can see it.

[neufer]

Days in the Sun

Fixed to a single spot for the entire exposure, the simple camera continuously records the Sun's path ... over the domes and radio telescope of the University of Hertfordshire's Bayfordbury Observatory. Dark gaps in the daily arcs are caused by cloud cover, whereas continuous bright tracks record glorious spells of sunny weather.

"In Hertfordshire, Hereford and Hampshire, hurricanes hardly EVER happen"

Huh? Harsh (perhaps horrid) driven men preferred to enhance fair lady.

[Rearranging the letters of
In Hertford, Hereford, and Hampshire, hurricanes hardly ever happen.
as done by hand by Adie Pena. (2008)]

[FloridaMike]

I noticed this image in the Recent Submissions thread and was impressed at the statuary beauty of it, as if this progression of arcs had a tangible presence, sculpted in marble. But I didn't bother to find out more about the picture or how it was made. Now that I have learnt that this is an unbroken six months' exposure taken with the kind of camera that Leonardo da Vinci could have used - except that he didn't have any photographic paper - I'm more impressed than ever. How clever! How simple! How beautiful!

The photographer, Regina Valkenborgh, is not an astronomer but an artist using pin-hole photography to explore the possibilities of this ancient technique to make records of reality.

How smart. How simple. How beautiful.

Ann

well said Ann.

[neufer]

What a brilliantly simple, but effective idea! I love this, thanks APOD. It's the sort of project every school child could be given the opportunity to try out, using materials that cost next to nothing.

Things like this can really capture the imagination.

<<NASA has funded initial research into the New Worlds Mission project, which proposes to use a pinhole camera with a diameter of 10 m and focus length of 200,000 km to image earth sized planets in other star systems.

The formula used today for calculating the optimal pinhole diameter was evolved by Lord Rayleigh:

• 

where d is pinhole diameter, f is focal length (distance from pinhole to image plane) and λ is the wavelength of light.>>

[starstruck]

A 10 meter diameter hole . . that has to be some pin!

http://www.nasa.gov/vision/universe/new ... mager.html

Reckon I'll stick to making it from a beer can . . it has certain advantages

. . but I'll be sure to use the formula (oh yeah!)

[neufer]

A 10 meter diameter hole . . that has to be some pin!

http://www.nasa.gov/vision/universe/new ... mager.html

I quite don't know why a 10 meter telescope would be needed.

A large cluster of 25 cm telescopes (with filter wheels instead of spectroscopes)
acting as the pinhole camera's screen would seem to make more sense, IMO.

[Beyond]

All the beer companies are in cahoots in promoting the pin hole camera to boost sales.as if anybody really needed any encouragement
for the cameras and for me, right

[cHARLIE pATRIOT]

I AM GUESSING THAT THE ROTATION OF THE EARTH IN SYNC WITH EARTHS ORBIT AROUND THE SUN MAKES THE PATHS SEEM LIKE A SINE WAVE RATHER THAN AN ARC.???? Pretty clever idea and I'm gonna teach it to my great grandson when he's old enough.

[neufer]

I AM GUESSING THAT THE ROTATION OF THE EARTH IN SYNC WITH EARTHS ORBIT AROUND THE SUN MAKES THE PATHction SEEM LIKE A SINE WAVE RATHER THAN AN ARC.????

It involves the fact that the back of the pinhole camera is a cylinder whose focal length goes to zero in the due east & west directions.

[Flase]

<<NASA has funded initial research into the New Worlds Mission project, which proposes to use a pinhole camera with a diameter of 10 m and focus length of 200,000 km to image earth sized planets in other star systems.

Interesting. It seems to be both a pinhole and a "starshade". Such a thing has always seemed a good idea to me; the use of a shade to block out a star's glare so you can see its planets. They use one already in the SOHO solar observatory.

I'm startled by this claim, though:

Finally, the NWI would swing into imager mode, the two collector spacecraft executing a complicated dance around the combiner craft to build up an image of another world. With the ability to resolve distant objects about 100 kilometers (60 miles) across, New Worlds Imager should be able to see clouds, continents, and oceans, giving us the first true pictures of a planet far from our own solar system. Not bad for the old pinhole camera.
(http://www.nasa.gov/vision/universe/new ... mager.html)

I'm not sure how far away such a planet could be. The obvious candidate in the search for planets would be Alpha Centauri and it would truly be an event if we could take such images. What about Pluto and the asteroids for starters?

[Flase]

Of course it would then take 100,000 years to travel to the place. Any probes sent to another system would be overtaken in mid-flight by something sent a century later and the glare would also make it very difficult to communicate with such a probe...

[alter-ego]

<<NASA has funded initial research into the New Worlds Mission project, which proposes to use a pinhole camera with a diameter of 10 m and focus length of 200,000 km to image earth sized planets in other star systems.

Interesting. It seems to be both a pinhole and a "starshade". Such a thing has always seemed a good idea to me; the use of a shade to block out a star's glare so you can see its planets. They use one already in the SOHO solar observatory.

I believe the the link(s) presented have led to some confusion. The 2005 article on Dr. Cash's New World Imager approach for imaging exoplanets does utilize a 10-m pinhole, but not a starhade. Although a physical aperture includes a block of some sort to creat an aperture, the pinhole "perfect lens" has ≈10 milliarcsecond resolution (10 meters in the image plane) and is meant to isolate an exoplanet with it's narrow field of view. Whereas with Cash's 2010 NWO proposal, the flagship New World Observer uses a starshade WITHOUT a pinhole with the JWST. On the starshade, the petal-looking perimeter is a special "apodized" design which significantly (many orders of magnitude) supresses diffracted light in the regions of interest. Specifically, modeling predicts central startlight supression to 10^-10 within 75 milliarcseconds. I'm not sure, but I believe that today, the starshade may be the primary path of interest.

Starshade only

I'm startled by this claim, though:

Finally, the NWI would swing into imager mode, the two collector spacecraft executing a complicated dance around the combiner craft to build up an image of another world. With the ability to resolve distant objects about 100 kilometers (60 miles) across, New Worlds Imager should be able to see clouds, continents, and oceans, giving us the first true pictures of a planet far from our own solar system. Not bad for the old pinhole camera.

I'm not sure how far away such a planet could be. The obvious candidate in the search for planets would be Alpha Centauri and it would truly be an event if we could take such images. What about Pluto and the asteroids for starters?

Another bit that needs some clarification. Not stated is that an array of two starshades and two primary collecting telescopes (~4-meter class) are needed to achieve the quoted resolution. Their light is combined at the "combiner craft" Assuming a visible wavelength of 500nm, and using two telescopes (and two starshades) separated by 1500km, 100km would be the limiting resolution at 10 parsecs (~33lyr) Note, that corresponds to ≈60 nanoarcseconds, or ≈ 1600x higher resolution than the single starshade/collector. (See left)

Lastly, implimenting these tools for objects in our solar system may be feasible in that we always find new, unplanned ways to use new tools. However, a key goal today for NWO is to look for life by way of finding oxygen on planets in the habitable zone. That pretty much puts pluto and asteroids at the bottom of the priority list, and given the physical expanse of these planet-hunting systems, tracking solar system objects could be problematic as they move very fast relative to planets light years away.