Steve MacLean works alongside the International Space Station at 29,000 km per hour. Few human beings leave the planet. Even fewer have the privilege to make a spacewalk outside the International Space Station. He's one of three Canadians to ever do so. The Canadarm2 hangs over him like a crane. He's difficult to spot in the photograph. His spacesuit is the same colour as the station's trusses. A deep blue ocean slides above him. It looks like a sunny day. There are hardly any clouds. Just a few wisps of cirrus. Beach weather.

Many astronauts say that photographs never quite capture what they see in orbit. Some essential nuance is lost. But when MacLean describes the experience of his spacewalk, it sticks with me.

"I inhaled the beauty of Earth."

Light glitters across the water during the next sunrise, which happens every 90 minutes. Every detail on its surface as small and finely sculpted as a newborn's hands. Perhaps they watch continents roll by while wrapped in the silence of their spacesuits. One pinch of stardust looking down at another. How does someone say good-bye to that?

The planet seems vast and immovable while I'm on it. But in my books, the sky is as thin as skin. Everything is suspended like motes against a black tarp. This is the first step back into the universe. We're compelled to return home like salmon, swimming upstream one rocket at a time. Even now, people are working in space. It's reassuring. Life goes on. We come by this urge honestly. Most of the human body is manufactured in the core of stars. My body—sweaty palms, thudding heart, faulty innards—is celestial in origin.

I take 100 mg of ferrous fumarate every morning. The pill is red and slightly rounded like a Smartie. It slew a sun once. I pop it into my mouth, then take a gulp of water. There's a certain poetry to it. A cycle. Maybe I'm destined for a slow burn. Maybe I'm almost out of fuel. Maybe something dark and heavy is growing in my core, too. Only time will tell. I spend days agonizing over possible scenarios.

I wouldn't know how to say good-bye. Not to Earth or any of the people living on it or the life I have. That's the problem. I'm young. I'm brief even for a human being. A blip of thought that glowed for a moment, then dimmed . When our sun goes out, it will be unremarkable. I don't want to be condemned to the same fate. Reluctantly shedding layer after layer of myself until I'm nothing but a cooling lump shrouded in darkness.

An ultrasound is scheduled for 10:30 a.m. Relativity dictates that time, by its very nature, is elastic. Like light, it bends. It's malleable. When something exerts enough gravity or achieves enough speed, time slows down. If you can hit the speed of light, time will stand still. You'll stay as you are now. Maybe that's all dying is. You keep moving forward; it's everything else that stops.

The nature of time, like the speed of light, is not something I encounter on a daily basis. But on the day of my ultrasound, as I pull into the parkade, it's all I can think about. I look down at my phone. It's fully charged. The clock moves forward, but the intervals between each minute feel taut. Once the results are in, I'll call my mum. This may be the last moment I have as myself. I wonder how I'll feel weeks from now. What will I know about myself, then?

There's nothing else for it. I step out of my car and inhale.