Random Post 2

Our Sky is Disappearing and There's Nothing We Can Do About It

If you were to go outside far from the lights of the city at night and look into the sky, you may be astounded by the number of stars. If you're far enough away from the city, it's a breathtaking sight. All in all, estimations of the number of stars that we can see with the human eye range from about 5,000 to a little over 10,000. A massive number when you consider the size and scale of what a solar mass is, but small in comparison to the estimated  200,000,000,000,000,000,000,000 stars which exist within the universe. Many of these stars are observable in their galactic clusters through the use of high-powered telescopes, but this might be a privilege that humans right now get to experience.

To understand why there are a couple scientific rules we have to get down.

1. The fastest light (and any matter) can go is at the speed of light.

2. The universe is constantly expanding.

3. The universe is really, really big (and some things we just don't know).

If the concept of lightspeed is new to you, I'll give a very quick breakdown. Light is a real thing. It's not matter, it's energy. Just like it takes time for electricity to move through wires, light energy (or photons) takes time to move through space. Once this light reaches your eyes, your brain processes it into an image of the emitting object at the time it was emitted, not at the moment. 

The light energy from the sun takes about 8 minutes to reach earth. When you look at the sun, you're seeing an image of the sun eight minutes ago. If we looked at an object exactly one "lightyear" away, we would be seeing an image of it a year ago. 

The universe is constantly expanding away from itself and has been since its start. Why it does this, we aren't entirely sure, but we know that it does. The further things get from one another, the quicker they expand away. At around 18 Billion lightyears away from earth, the space between earth and other celestial objects grows faster than the speed of light. The photons that once reached Earth will eventually be outpaced by the growth of space, and the last photons released before they crossed that point 18 billion years ago will be the last possible image of that body that ever reaches our eyes, and they will be gone forever.

Now there's no reason to stress, these stars only cross the point of being unreachable at a rate of 60,000,000 every second. Horrifying in some respects, but maybe comforting in others. The universe is still too young for us to have seen any stars disappear out of our sky. In fact, we have another 4 billion years before that even starts to happen. If Earth was a 24-hour clock and now was midnight, human life would have only started one minute and seventeen seconds ago.

The timescale is unfathomable, and it's impossible to predict what we might accomplish (or destroy) in the time before the sky starts to fade. For now, we can take solace in the fact that we can see these stars. Billions of years in the future, those living in our supercluster may never have the privilege of knowing the true limits of the universe, let alone being able to see it.