Perspective shift

Looking at the night sky can do more than simply open up a window to the wider universe.

 
 Illustration by Emily Chandler

Illustration by Emily Chandler

 

Field Studies is a monthly column by Clare Watson, who travels around Australia and the world exploring science by participating in studies, visiting research institutes, going on trips with scientists, and a lot more.

Friday, January 8th, 2016

Humans have spent millennia looking at the stars. Like moths to a flame, our eyes are drawn skyward once the sun sets. Our ancestors searched for meaning in the sky, found constellations that rose each month and linked them to the mythological stories. Aboriginal tribes sketched out maps across the night sky to remember waypoints for long journeys into distant lands. (Remarkably, these maps now align with major highways.) But in booming cities, where streetlights, pollution and our tunnel vision impede our view of the universe, we can easily lose perspective and forget that Earth is only one planet orbiting one star in a matrix of other solar systems and galaxies.

It’s said that the environmental movement was inspired by one grainy photograph: Earthrise. Captured by the astronauts aboard Apollo 8 as they rounded the backside of the Moon, we humans saw for the first time a picture of our Earth from deep space. And once we could see the Earth this way, as a marble orb bobbing on a black lunar sea, we could appreciate our fragile dependence on the planet. It put us in our place.

Along my travels last year, I read an essay written by Tim Winton. Claustrophobic in cities, Winton describes the derivation of his Australia from “the grandeur of the land.” His eloquent words drew my feelings of nostalgia. Chunks of my own childhood were spent driving the length and breadth of our country and camping beneath the stars with my two-tent, four-person family. I again felt the comfortable embrace of space after 11 months on the road last year when my fiancé and I bumped through the Salvador Dali deserts of south west Bolivia, had our passports stamped at a windswept border post and crossed over into Chile. We tumbled out of the 4WD in San Pedro de Atacama. 

San Pedro is a remote, dusty town that serves menu del dia reminiscent of Spain and has tapped into nature-based tourism. It is situated on the high plateau of the Atacama Desert, the driest non-polar desert on Earth, at an altitude 200m higher than Mt Kosciuszko (2,407 metres). Volcanoes, salt flats and geysers dominate the landscape around San Pedro but the town is rarely shadowed by clouds, making it one of the best places in the world to conduct astronomical observations. The Atacama Large Millimeter Array (ALMA) is a prime example: built 50km east of San Pedro, ALMA comprises 66 antennae (think of the Parkes radio telescope — that’s one) that are spread over distances up to 16 kilometres and can merge their data to function as one giant telescope. 

Unfortunately, when we were passing though, the ALMA public open days were booked out — but the astronomy tour we took one night was no less than breathtaking. We were bussed out of town, the interior lights dimmed and the window cold against my temple, until San Pedro was a distant bulb on the horizon. We assembled in a circle; the night sky yawned above us. What we thought was dark got darker still; stars amongst stars began to appear as our eyes adjusted. Our guide pointed out fabled constellations with a green laser so intense it appeared to shrink the distance between us and the stars: a momentary illusion.

After the laser show, we moved across to the decathlon of telescopes. One was so large that we had to climb up a ladder to look into the eyepiece. Each was positioned on one object in the sky: Uranus, which looked like a flat, blue disk because the planet’s atmosphere, high in methane, scatters light to a wavelength that registers blue in our eyes; a ghostly nebula, which is an interstellar cloud of dust and gas; and clusters of stars that to the naked eye looked like a lone star but in fact they are hundreds or thousands of stars gravitationally bound. 

My favourite of the night’s spectacles was watching the brightest star at the bottom of the Southern Cross crackle red, blue and white, like popping candy. This effect is called refraction. When light hits the Earth’s atmosphere, it slows and bends because the atmosphere is denser and has a higher refractive index than outer space — it creates an obstruction. The white light is split into a rainbow of its constituent wavelengths, like the album artwork of Pink Floyd’s Dark Side of the Moon. To the naked eye, starlight is white but on closer inspection, with the aid of a telescope, we can see refraction at play.

Although no one would have seen it, I was grinning to be underneath these southern stars again. To see these astronomical wonders that I had studied in high school textbooks with my own eyes was thrilling. To be reminded how mind-boggling big our ever-expanding universe is while standing under an open sky — in the cold, with such clarity it was as if there were no atmosphere — was astounding. 

The starlight that reaches our eyes left those stars perhaps when we were born, or when our grandparents were before us. Essentially, we’re looking back in time because that light has travelled from its origin for decades, or maybe even centuries, to land on our retinas.

To measure distances in space, astronomers often refer to light years. One light year is the distance that light can travel in one year: that’s 9,460,000,000,000 kilometres. To give you a reference, the closest star to Earth, other than our sun, is Proxima Centauri and it’s about four light years away. Our moon is on average a measly 384,400 kilometres from Earth, a distance light covers in just about one second — and that was a huge step for mankind. It’s humbling to remember that our Earth is really just a speck, a blue dot spinning through the expansiveness universe.     

A few weeks later we were hiking in Patagonia, an equally spacious place. I noticed a girl with a tattoo of the Southern Cross on her shoulder, a common tattoo for some Australians, but hers was off kilter, tilted on an angle. I thought it strange but then I realised the cross was drawn from her Chilean perspective, slanted as it sits in her sky.

 

 

Interested in astronomy yourself? You might like to visit the Sydney Observatory, which runs night tours year round, visit another great observatory across Australia, or download one of the many star map apps available for smart phones.

Edited by Jack Scanlan