Back in August of 2023, I grabbed my telescope, told my parents not to wait for me, and drove into the middle of nowhere. Stargazing has become essential to my life, and I hadn’t been in a few months, so I was ready to go. The nights I go stargazing, I feel free, spending a few hours alone with the universe. I’m no astronomer by any means, but I enjoy studying the night sky. I’ll usually pick one celestial body to focus on, whether that be Jupiter and its moons or some distant nebula I can barely see. That night, I decided to study Polaris.
As I get out of the car, I pause to let my eyes adjust to the darkness. Carrying my telescope to the middle of the clearing, I’m careful not to trip on any rocks or step on any fireflies. I set my telescope down, close my eyes, and take a deep breath. As I open my eyes, I look up at the glittery sky above me.
I could spend hours just aimlessly looking up at the sky, but I have a mission, so I get to work. First, I search for the Big Dipper. Once I find the Big Dipper, I follow it to the Little Dipper. As I trace along its handle, my eyes finally settle on Polaris, the last star in the Little Dipper.
Apparently, Polaris is not one star, but three stars, all very close together. Hoping to see that for myself, I carefully aim and focus my telescope. Looking through the eyepiece, I find one bright point. My eyes dart around, desperately seeking a second and third point of light, but I find nothing. A younger version of me would have been discouraged, but I understand the limits of my telescope. I decide to wait for the moon to set, hoping the other stars will be easier to see without so much ambient light.
Looking up at the sky, I think about the other facts I know about Polaris. I recall someone once telling me it’s called the North Star, so I pull out the compass app on my phone and point it in the direction of the star. The screen reads 0°, perfectly north. That must be a coincidence, I think to myself. Once it moves, it won’t be perfectly north anymore.
Over the next hour, I watch the stars move across the sky, occasionally pointing my telescope at whatever seems interesting. Every once in a while, I check on Polaris, which is still perfectly north. In fact, it hasn’t moved at all. How has it not moved? Everything else is moving. Even the Little Dipper is moving, what’s going on with Polaris?
I sit there confused for a while before I try a new approach to understand what’s going on. Rather than consider myself a stationary observer on Earth, I pretend I’m an observer from space, looking at the Earth. From my new perspective, I see the Earth rotate. Its axis of rotation goes through the North and South Poles. The rest of the Earth keeps spinning while that line stays still.
And that’s when it hits me.
If Polaris is a fixed point in the sky, then it lies along the Earth’s axis of rotation. That means, if you went to the North Pole and looked straight up, you would see Polaris. Anywhere else on Earth, Polaris acts like a beacon to the North Pole. That’s why Polaris never moves. That’s why it always points north. Satisfied, I lay down, enjoying my small victory. This peace lasts for approximately one minute before my brain starts asking questions again. This fixed point in the sky must have some interesting properties, so I close my eyes and think about Polaris geometrically. I can’t fully fathom how far away Polaris is, so I just pretend it’s infinitely far away. Under this assumption, if I draw a line from myself to Polaris, it’s parallel to the Earth’s axis of rotation. In this mental model, I draw a plane tangent to the Earth from where I am. The Earth may not be flat, but I can pretend it is locally for the sake of mathematics. With this little diagram in my head, I realize just how important the North Star is for navigation. If you can find the angle between Polaris and the horizon, that angle is your latitude.
I pull out my notebook and a flashlight to make sure I did that calculation correctly. Yep, the angle between Polaris and the horizon is your latitude. I can’t believe I just figured that out. Is this how astronomers figured out celestial navigation centuries ago? I doubt I’ll have any more revelations for the rest of the night, so I relax on the ground, watching the other stars journey across the sky. As my watch passes midnight, I pack up my telescope, wave goodbye to the stars, and start heading home.
I never did see the three stars that form Polaris, but it is a fixed point in the sky, so I’ll always know where to find it.