TRAILS OF THE SUN

So­larg­ra­phy cap­tures cos­mic time in a sin­gle frame. LAU­REN FUGE ex­plores how such a sim­ple tech­nique in­spires a sense of con­nec­tion to the uni­verse.

Cosmos - - Cosmos Science Club -

AS DARK­NESS FALLS over the Payette River in cen­tral Idaho, Chuck Bueter makes his way along the river­bank to what ap­pears to be an oddly dec­o­rated tree. Nine as­sorted alu­minium cans are duct-taped to the slen­der trunk. They are nei­ther rub­bish nor art – these cans are pin­hole cam­eras, and they’ve cap­tured some­thing spectacular about our world that Bueter wants to share.

It is 21 Au­gust 2017. A few hours ear­lier, at 11.28 am Moun­tain Day­light Time, a to­tal so­lar eclipse shrouded this part of the US in shadow. A record of the mo­men­tous event is curled in­side each can on a strip of pho­to­graphic pa­per: a so­lar­graph.

Bueter, an ama­teur as­tronomer, set up these long-ex­po­sure pin­hole cam­eras by the river with the help of lo­cal chil­dren the pre­vi­ous day. Be­fore sun­rise he opened the ‘shut­ters’ – pieces of tape over the pin­holes. “I was the only one up be­fore the Sun; it’s hard to sleep on eclipse morning!” Bueter laughs.

Now, af­ter sun­set, Bueter takes down the cans and re­moves the pho­to­graphic pa­per in­side. Their im­ages cap­ture the Sun’s move­ment across the sky from dawn to dusk. Its jour­ney is scrawled on the pa­per in a bright blaz­ing arc, marked by a fuzzy gap where the Moon has passed in front and blocked its light.

“It’s like Christ­mas,” Bueter says. “It feels like I’m open­ing presents.”

One of the nine eclipse so­largraphs in par­tic­u­lar was “pretty damn cool”. So cool, in fact, that he sent it to NASA, which fea­tured it on the agency’s web­site as As­tron­omy Pic­ture of the Day (APOD). Friends and strangers alike wrote to him to ex­press en­thu­si­asm and support. “I got lucky,” he says.

Lucky or not, Bueter’s im­age is part of a resurg­ing in­ter­est in the art and science of so­larg­ra­phy. Its roots can be traced back to 19th cen­tury Bri­tish pho­tog­ra­phy pioneer Wil­liam Henry Fox Tal­bot, the first to record an im­age on light-sen­si­tive pa­per.

Pa­trick Mccauley, a PHD can­di­date in so­lar physics at the Univer­sity of Syd­ney, says pho­tog­ra­phy has been ap­plied to the Sun al­most since it was in­vented, “and its im­por­tance to so­lar science can’t be un­der­stated”.

The spe­cific tech­nique used by Bueter emerged in 2000 in a project called So­laris1, cre­at­ing so­largraphs with pin­hole cam­eras – with­out lenses – and light­sen­si­tive pa­per that im­me­di­ately re­veals the im­age with­out chem­i­cal devel­op­ment.

Bri­tish film­mak­ers and keen so­larg­ra­phers Wendy Be­van-mogg and Austin Capsey ex­plain that us­ing a cylin­der for the pin­hole cam­era en­ables a wide field of of view, “which means in the win­ter we can cap­ture a com­plete track of the Sun from sun­rise to sun­set”.

Since very lit­tle light en­ters the cam­era, it must be se­curely at­tached to a firm place – like a fence or tree – and left for a pe­riod that ranges from a day to six months. A day is all you need to cap­ture an eclipse; six months will show you the full ex­tent of the Sun’s chang­ing path through the sky, from a low bump in mid-win­ter building up to a soar­ing loop in mid­sum­mer. The im­ages are both eerie and beau­ti­ful.

“We’re used to the idea of high-speed pho­tog­ra­phy cap­tur­ing a small tran­sient mo­ment in time, while so­larg­ra­phy is ac­tu­ally the op­po­site of that,” Capsey says. It cap­tures “the slow and steady sea­sonal heart­beat of the Earth”.

The Sun’s dif­fer­ing tra­jec­to­ries re­flect the Earth’s ori­en­ta­tion as it or­bits the star: in win­ter its axis tilts ‘away’ from the Sun, which there­fore fol­lows a low path in the sky; in sum­mer the axis tilt ‘to­wards’ the Sun, which ap­pears higher in the sky.

Of course, as so­lar physi­cist Mccauley notes, so­largraphs are not used for cut­ting-edge re­search: “For that we use high-res­o­lu­tion tele­scopes that track the Sun as it moves across the sky, along with non­pho­to­graphic in­stru­ments like ra­dio tele­scopes and par­ti­cle de­tec­tors.”

But since pin­hole cam­eras are cheap and easy to make, and only pa­tience is needed to cap­ture a snap­shot of cos­mic time, so­larg­ra­phy is a great way to in­tro­duce peo­ple to the grand scale of our uni­verse and the math­e­mat­i­cal dance of the Sun and the Earth.

Bueter, for ex­am­ple, is pas­sion­ate about us­ing so­larg­ra­phy to teach his com­mu­nity about as­tron­omy. He be­gan in 2016 for In­di­ana’s bi­cen­ten­nial cel­e­bra­tion, when “there was a big ques­tion posed: how do you cap­ture the essence of time?” He turned to so­largraphs as a vis­ual way to cap­ture time’s pas­sage, plant­ing cam­eras atop a base­ball sta­dium, on a flag­pole, in parks, out­side his bar­ber’s shop, and on the rooftops of a church and sev­eral schools.

“I love telling a bunch of kids: ‘Let’s do some­thing dan­ger­ous that your parents have told you never to do: let’s look at the Sun!’” Bueter says. “It’s great to start a di­a­logue with them, to try to eke out what they can dis­cern by look­ing at a so­lar­graph. We ask them to think about what the lines rep­re­sent, why the Sun is some­times high or low, why there might be miss­ing or dot­ted lines like Morse code, how that might be re­lated to the weather or sea­sons.”

Bueter also runs work­shops on how to make so­largraphs. “Each so­lar­graph is unique and per­sonal, which makes it fun for the per­son do­ing the in­ves­ti­ga­tion,” he says with in­fec­tious en­thu­si­asm.

In Bri­tain, Capsey and Be­van-mogg also in­volve

the public in so­larg­ra­phy. They have held sev­eral ex­hi­bi­tions and work­shops, and cre­ated a short film about the way so­largraphs con­nect them to the nat­u­ral world. “To most peo­ple so­larg­ra­phy is a com­pletely new process and gen­uinely does show peo­ple the world in a way they’ve never seen it be­fore,” Capsey says.

An­other Bri­tish pho­tog­ra­pher, Matt Big­wood, has used so­larg­ra­phy to ex­plore how to see the world in a dif­fer­ent way. First hooked on pin­hole pho­tog­ra­phy as a child, he set up pin­hole cam­eras at his daugh­ter’s school to pro­duce ethe­real so­largraphs.

“The chil­dren have all been raised in an in­stant, dig­i­tal world,” Big­wood says. He en­joyed show­ing his daugh­ter’s class a com­pletely dif­fer­ent style of pho­tog­ra­phy of the nat­u­ral world.

On a larger scale, Fin­nish artist Tarja Trygg ran an in­ter­na­tional project be­tween 2006 and 2012 to get the public in­volved in so­larg­ra­phy, set­ting up pin­hole cam­eras across the world to record how the Sun’s path changes at dif­fer­ent lat­i­tudes. The re­sult was a gallery of 300 so­largraphs on her web­site, a short film and a wealth of teach­ing ma­te­rial. Dur­ing this pe­riod she also teamed up with the Euro­pean South­ern Ob­ser­va­tory (ESO) to com­bine her artis­tic ap­proach with a sci­en­tific point of view. So­largraphs were made over six months at ESO’S tele­scope sites in Chile.

“Cu­rios­ity is a hu­man trait,” Trygg says. “So­larg­ra­phy made me in­ter­ested in the uni­verse and made me see how our planet Earth is a tiny part of a whole.”

Mccauley, whose PHD is fo­cused on so­lar physics, sees as­tron­omy cap­tur­ing the public imag­i­na­tion in a way most other sci­ences don’t. “As­tron­omy has also taught us that Earth re­ally is a spe­cial place,” he says.

This mes­sage is cen­tral to the work of many so­larg­ra­phers, who aim to get peo­ple talk­ing about the world around them, so per­haps they will take an in­ter­est in pro­tect­ing it.

Bueter wants to pro­mote a cul­ture that em­braces so­lar en­ergy. “When I talk about so­lar pan­els I get a lot of push­back from peo­ple who just dis­mis­sively say that it’s al­ways cloudy here,” he says, “but if they cre­ate their own record of the Sun they can quan­tify how of­ten the Sun shined or not. Ev­i­dence is more com­pelling when it’s ev­i­dence that you your­self have de­rived.” LAU­REN FUGE is a free­lance science writer based in Ade­laide, Aus­tralia.

IM­AGES 01 Matt Big­wood 02 Chuck Bueter / Night­wise.org 03 Austin Capsey / Wendy Be­van-mogg, Knapp Ridge Films

02 | Pin­hole cam­eras set up by Chuck Bueter along the Payette River in Idaho to cap­ture the to­tal so­lar eclipse of 21 Au­gust 2017.

This so­lar­graph made in Glas­ton­bury, Eng­land, cov­ers a six- month pe­riod, from sum­mer sol­stice to win­ter sol­stice in 2015. A 35 mm film can­is­ter was used for the pin­hole cam­era. 03

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