Starship Asterisk*

Thanks, Art. Really interesting.

Ann

[url=http://asterisk.apod.com/viewtopic.php?f=9&t=24346][b][i]APOD: A Triangular Shadow of a Large Volcano (2011 Jul 05)[/i][/b][/url]
[quote="APOD Robot"][url=http://apod.nasa.gov/apod/ap110705.html][img]http://apod.nasa.gov/apod/calendar/S_110705.jpg[/img] [size=150]A Triangular Shadow of a Large Volcano[/size][/url]

[b] Explanation: [/b] Why does the shadow of this volcano look like a triangle? The [url=http://en.wikipedia.org/wiki/Pico_del_Teide]Mount Teide[/url] volcano itself does not have the strictly [url=http://mste.illinois.edu/users/pavel/java/pyramid/]pyramidal shape[/url] that its geometric shadow might suggest. The [url=http://www.atoptics.co.uk/atoptics/mtshad.htm]triangle shadow phenomena[/url] is not unique to the [url=http://www.youtube.com/watch?v=qHUZr8ixrRA]Mt. Teide[/url], though, and is [url=http://apod.nasa.gov/apod/ap101205.html]commonly[/url] [url=http://apod.nasa.gov/apod/ap080301.html]seen[/url] from the tops of other [url=http://apod.nasa.gov/apod/ap110417.html]large mountains[/url] and volcanoes. A key reason for the strange dark shape is that the observer is looking down the long corridor of a sunset (or sunrise) shadow that extends to the horizon. Even if the [url=http://www.youtube.com/watch?v=RiU7_Mpn_lc]huge volcano[/url] was a perfect [url=http://www.schubart.net/rc/]cube[/url] and the resulting shadow was a long rectangular box, that box would appear to taper off at its top as its [url=http://apod.nasa.gov/apod/ap100804.html]shadow extended[/url] far into the distance, just as parallel [url=http://www.hickerphoto.com/data/media/7/train-tracks_9510.jpg]train tracks[/url] do.[/quote]

[url=http://www.eso.org/public/images/potw1205a/][size=120][b][i]A Shadow at Sunrise (Atacama Desert, Chile)[/i][/b][/size][/url]
ESO Picture of the Week | 2012 Jan 30
[quote][float=right][img3=""]http://www.eso.org/public/archives/images/screen/potw1205a.jpg[/img3][/float]In this photograph, taken by ESO Photo Ambassador Gianluca Lombardi, the Sun is rising and bathing the Chilean Atacama Desert in a familiar soft reddish glow. But this image, from 13 July 2011, has also captured something out of the ordinary: a dark shadow lurking on the horizon.

Gianluca took this photograph from Cerro Armazones, looking west. Armazones is the future home of the world’s biggest eye on the sky: the upcoming [url=http://www.eso.org/public/teles-instr/e-elt.html][b]European Extremely Large Telescope (E-ELT)[/b][/url]. The Sun rose behind Gianluca in just the right place to cast a daunting shadow of the 3060-metre-high mountain onto the Earth’s atmosphere in the distance. The shadow can be seen reaching over the vast desert landscape, and up across the horizon on the left side of the image.

The bright summit visible on the right of the image is Cerro Paranal, at an altitude of 2600 metres. It is only 20 kilometres from Cerro Armazones, and is the home of [url=http://www.eso.org/public/teles-instr/vlt.html][b]ESO’s Very Large Telescope (VLT)[/b][/url]. Both sites have exceptional astronomical observing conditions. To its right is the adjacent peak where the [url=http://www.eso.org/public/teles-instr/surveytelescopes/vista.html]VISTA survey telescope[/url] is located and to its left, on the horizon, are the Paranal Observatory’s basecamp and Residencia.

The white road winding across the bottom-left corner of the photograph is the route to the summit of Cerro Armazones.

[b][i]Credit: ESO/G. Lombardi[/i][/b]

[url=http://www.eso.org/public/images/potw1205a/zoomable/][b][i]Zoomable Image[/i][/b][/url][/quote]