The night sparkles brightly with stars, glittering in the sky the way sunlight dances on a lake. There in the heavens, is a new light – the colour of grass and leaves and life. Standing tall amongst the swaying grass, a group of people gaze at the comet – though they don’t yet know that’s what it is. To them it is a thing of magic, and of power. Breath-taking in its beauty, the green comet moves across the heavens and vanishes from the sky within the span of a lunar cycle. It is never seen again.
Fifty thousand years later, the comet returns to Earth. This time the skies are brighter, choked by pollution from artificial lights that mimic the stars. Streetlamps and lit windows create electric constellations that buzz and hum. They whisper constantly. A fluorescent smog obscures the night; in the past decade, our skies have nearly doubled in brightness due to light pollution. Now all but the brightest are hidden to the naked eye. Far above us the stars continue to shine, unaware that fewer eyes gaze up at them in awe.
In the darkest areas though, they are still visible to those who look for them. The Milky Way cuts the sky in two, a pale ribbon upon a sea of blue-black. Space is a teeming void. Filled with mysteries beyond our understanding, the darkness is anything but empty. There in the sky – little more than a smudge of green – an ancient comet passes us by once more. How many times has it visited us? What secrets about our world does it know?
Dubbed C/2022 E3 (or Comet ZTF) by astronomers, our sublime celestial visitor has been here before. When it last passed our world, it was the Stone Age. Throughout human history recorded and forgotten, comets and celestial bodies have been spoken about in hushed whispers filled with reverence and fear. To some, their appearance heralded great strife, to others, great blessings. Though we know now that comets are celestial bodies consisting mainly of ice, their beauty is no less palpable. Eager eyes still watch the skies, hoping to catch a rare glimpse of one as it trails through the night. For those who wish to experience this once in a lifetime opportunity, Comet ZTF will be at its perigee on February 1, when it is closest to Earth.
Our ancient friend, who once soared high above our Neanderthal cousins, may soon leave us entirely. If it returns, who knows what strange world may await it. Like the Earth, comets orbit the Sun. Pulled in by its enigmatic gravity, comets grow nearer and nearer until the Sun’s blistering heat melts their icy exteriors into gas. This creates their characteristic tail, or coma. Most pass by safely, continuing their orbit. Eventually, like Halley’s Comet, they will return. Not Comet ZTF though.
Fifty thousand years ago its orbit took it past the reaches of our solar system, deep into space. When it eventually leaves our orbit again, we don’t know how far it will travel. Comet ZTF is thought to be on a parabolic orbit, unbound from our solar system. As it leaves us behind, Comet ZTF will traverse a parabolic trajectory into infinity, never to return. Maybe one day it will pass us by again – if the stars align just right.
As I stand outside in the peaceful dark hoping to spot the comet, I wonder if thousands of years ago someone much like me did the same. Divided by millennia we are connected by the simple feeling of wonder – and the green tail of a comet, passing us by in the night.
If you would like to try and spot Comet ZTF for yourself, find a dark place away from light pollution late at night or very early morning. Here in the Southern Hemisphere, very late January and very early February are the best times to spot it. If you have binoculars or a telescope, they will aid you in your search – but if you’re very lucky, and it’s very dark you may just spot a faint hint of green amongst the darkness of the night sky.