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EarthSky // Today's Image Release Date: Jun 20, 2014

Celebrate solstice sun by viewing this cool solargraph

The streaks in the photos are sun-trails – the sun moving in its shifting path across the sky from day to day, over a six-month period.

This solargraph is a single long-exposure photo of the sun over a six-month period, between the December solstice of 2009 to the June solstice of 2010.  Image by APEX Telescope via Wikimedia Commons

This solargraph is a single long-exposure photo of the sun over a six-month period, between the December solstice of 2009 to the June solstice of 2010. Image by APEX Telescope via Wikimedia Commons

A solargraph, like the one on this page, is a long-exposure photograph that shows the path taken by the sun across the sky, over time. In this case, the time period is the six months between the December solstice of one year and June solstice of the next. The streaks in the photos are sun-trails – the sun moving in its shifting path across the sky from day to day over that six-month interval.

Llano de Chajnantor in the Atacama desert in Chile, home of the APEX Telescope. Astronomers acquired the solargraphy from here, in the process of assessing the site for use in professional astronomy.

The APEX telescope at the Llano de Chajnantor Observatory in Chile acquired this image over a six-month period, from about the time of the December solstice in 2009 until the June solstice in 2010. The astronomers inadvertently created art, but their original goal was to assess the quality of this site in Chile for astronomy.

The mostly unbroken sun-trails show that there were some clouds at the site during the six months — but not many. This solargraph is so sharp that holes in the fleeting clouds over Chajnantor on the few partly cloudy days sometimes managed to create individual “snapshots” of the solar disc (seen as dots in the broken sequences).

Read more about this image here

Everything you need to know: June solstice 2014

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