Milky Way Sails the Playa

Racetrack Playa is a dry lakebed in Death Valley.  It is a vast expanse, miles by miles, of dried mud cracks.  It is flat and nearly level, the north end merely inches higher than the south.  The occasional stone can be found on the playa, delivered by erosion forces on the surrounding mountains, falling down and rolling out onto the lakebed.  They are stones, not boulders, maybe a foot or two across, heavier than is convenient to carry away, but not heavy enough to protect them from magic seekers.

And the magic they seek is that many of the stones are found at the end of a long, physically engraved trail, recording their traversal of the ancient lakebed.  How could these stones have moved across the dry playa?  It has been a mystery to geologists for years.  Various theories have been proposed, and some have been tested, but it is a difficult research project.  The stones lie inert for years, and then, when next inspected, they have moved.  With new trails marking their path!  This is the magic that the stone thieves are after.

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Polaris on the Playa

One of the active topics in modern photography is the distinction between “blends” (combining multiple exposures from a single camera viewpoint), and “composites” (which combine unrelated images into a synthetic scene).  Both are valid uses of photography, but I prefer to limit my efforts to the former, hoping to reveal some scientific beauty in the result.

In this case the relative motion of the stars is “stacked” (added) from 2,335 10-second exposures.  Each frame looks like a normal picture of the sky, but when accumulated creates the star trail effect.  The frames were selected from the period after “astronomical twilight” when the sun is more than 18-degrees below the horizon.  On this date, official night lasted over six hours, and the star trails cover more than 1/4 of a full circle (and even Polaris shows that it is not exactly on the north celestial pole).

Although it was “night”, it was not completely dark.  The moon was up and illuminated the scene until it set around midnight.  This allows the foreground to show, including the “sailing stone” with its path on the dry lakebed trailing behind it, a contrast of time scales against the motion of the sky.

A final detail to explain:  the streaks below and to the left are the result of trains of Starlink satellites moving across the sky.  Dozens of satellites follow each other into and out of the sunlight at their altitude, reflecting it down to our observing position on the playa and creating its own trail on this image.

For more of the backstory on making this image and the next, see “A Night on the Playa – Part 2“.

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19 May 2021
Racetrack Playa
Death Valley National Park CA
Canon EOS Ra with EFS 10-22mm
2335 exposures, 8 sec @ f/4, ISO 3200 (6-1/2 hours)

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A Night on the Playa, Part 2

A sailing stone, the path behind it showing the route it took to get here.

There was a second wide spot in the road at the south end of the playa; we parked and continued our explorations.  This time we found stones sitting on the surface of the lakebed.  There were not many, and we had to hike a mile or so to find them.  Some sat happily contemplating their position in the uniform semi-infinite plane of mud cracks.  Others showed a faint trail of disturbed, and now solidified mud, leading to their current position.  These were the famous sailing stones! 

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A Night on the Playa, Part 1

Life highlights are those you can list on a single hand.  They are indelible events that exceed the normal range of our experience.  They may include a first kiss, the birth of a child, recognition of a career accomplishment, or the challenging hike to reach a beautiful mountain pass.  This is the story of adding one more of those outlier life experiences to my list.

Years ago, I had read about the geologic mystery of the “sailing stones” on the Racetrack Playa in Death Valley.  Death Valley is an intriguing place and not just because of its ominous (and deserved) name.  It is a geology and biology classroom, displaying the impacts of volcanoes intruding on sedimentary layers that have been shape-shifted into ribbons of colorful escarpments with water and wind-eroded features.  Somehow, the valley has fallen below sea level, and the water, when there is water, dissolves minerals from the mountains and finds its way to the bottom, where it evaporates and leaves the residue behind as a salt flat.

In the spring, the water also nourishes an intense flowering of desert plants, desperate to reproduce. For a few brief weeks, colorful plants and flowers adorn the roadsides and cover the otherwise barren hills.  I have been to Death Valley during this season, during a “superbloom” following an unusually wet winter.  It was a stunning display of flowers in this otherwise arid and nonviable setting, something I had never expected to see.  As impressive as this floral show was, I had really hoped to visit the famous sailing stones on the playa.

Flowers during the 2005 superbloom, in front of the Sierra Nevada mountains to the west of Death Valley.
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