Stars and auroras fill the night sky. They blink and swerve through the darkness, like race cars on a dark, winding, celestial freeway. For four months, they have been my steadfast companions, joining me on my walk to and from the Atmospheric Research Observatory (ARO) each morning. On calm, clear days, they cast green and white light downwards with such intensity that I can occasionally see my shadow and the forms and curves of the ice cap– everything bathed in ghostly colors, the auras of a cold, harsh and indifferent world.
On the darkest days, when the air is so cold and the wind so still that you feel like you’re floating in television static, I’ll drop to the ground and lay on my back, and view the night sky in repose. The Milky Way spins above me, its origin directly overhead. Billions of stars, each a distinct pinprick of light, each crying out the infallible laws of nature, which–if you hold your breath and quiet your beating heart–you can almost hear.
Astronomical twilight has begun, and though the night sky looks no different, from this day forward, each day it will become imperceptibly lighter out. Distant stars will begin disappear and the brightest will begin to dim. The auroras will still be visible, though less vibrant. They will fade from a bright green to a dull purple, and then finally evaporate, blending into the leaden sky like campfire smoke.
In a week, the moon will rise, so in a sense, this is our final week of pure darkness, our final week to trace spy satellites through the sky and count shooting stars. The moon, the South Pole’s pale sun, will bathe the ice cap in light, and obscure all other celestial phenomena. It will be bright enough to walk to ARO without tripping over myself, to see the silhouette of the facility from a quarter-mile away and to wander without fear of getting lost, off the flag line and into the never-ending expanse of the polar plateau.
By the time the moon sets, about two weeks after it rises, the sun will sit just 12 degrees below the horizon. It will be nearly as light out as when the moon was full and high. This is the start of nautical twilight, when distant landforms, hills and mountains, or in our case, drifts and the hard, wind-swept ridges of snow known as sastrugi, become visible on the horizon—when the ice cap begins to take on shape and transform from a uniform black expanse into a landscape with observable topography.
The sun won’t be visible at this point, but you can trace its daily transit around the horizon—an orange and blue glow at the intersection of the night sky and the earth. Each day, the glow growing more intense, the sun spiraling upwards more rapidly. Each day, the stars disappearing into the greying sky, the auroras becoming more amorphous and dull.
A colorful winter will give way to a pallid spring; a welcome change, carrying promises of vitamin D and warmer weather.