Where are we?

A map of the stars.

Feb 24, 2021

The universe is huge. It contains everything you’ve ever known, everything you can ever hope to know, and literally all of the girl scout cookies. It suffices to say it’s a very important place. To put it into a scale we can understand, it’s roughly the width of 64 septillion (64,147,540,000,000,000,000,000,000) school buses. Okay great, got it now? Neither do I, let’s start smaller.

If you’re reading this, you’re probably somewhere in the United States. (TBD on when I’ll be taking this newsletter global) Like we have touched on in previous newsletters, the continental United States is about 2,500 miles across as the crow flies. For anyone that can’t do the math in your head (I can’t either), that’s 0.013 light seconds. This means that light can go from New York to Los Angeles 75 times in a second. We’ll be using some form of this light measurement from here on out. Zoom out a bit and look at the entire Earth. Flat Earther or not we can all agree that the distance from one side to the other it is 0.13 light seconds (~25,000 miles). If we zoom out even more, we can see our celestial little sister, the Moon. The Moon’s orbit is slightly elliptical, meaning its distance from Earth fluctuates, but on average, the Moon is 1.28 light seconds away (~240,000 miles). This means that, when we were communicating with the astronauts on the moon, it took our messages 1.28 seconds to reach them and their responses 1.28 seconds to get back; yielding a round trip communications delay of 2.56 seconds. Not bad.

As we go farther, we begin to see our solar system neighbors: Mars and Venus. Like the Moon, they are not always the same distance away from us, but this case is more extreme. They have different orbits than we do and therefore revolve around the sun at different rates – Mars goes more slowly, and Venus is faster. As a result, there is a maximum and minimum distance from us that they can be. [1]

At its closest, Mars is 188 light seconds away (35 million miles), and at its farthest, it’s 1,300 light seconds away (250 million miles). This puts the average communications delay at about 22 minutes. This starts to become a pain when communicating with things on Mars, especially when those things become humans.

Next, we can see our whole solar system come into view. There are things out there past Pluto, and this technically is an incorrect assumption, but for our purposes we can say that the radius of Pluto’s orbit defines the width of our solar system. This is 20,000 light seconds, 333 light minutes, or 3.7 billion miles across. This is about what your view should look like: [2]

As we continue to hit the little ‘-‘ button, our view begins to get dark. There aren’t a whole lot of things near our solar system, at least on our scale. It’s not until we get to the scale of light YEARS that we begin to see things again. On this scale, our solar system looks tiny, remember that it’s only 333 light minutes across. You could fit over 6,000 of our solar systems between us and the nearest star, Alpha Centauri. This star system is over 4 light years away. With the fastest spacecraft mankind has ever created it would take about 7,000 years to get there. This can be made faster with better technology, like solar sails, which can cut this time down to something like 20 years. That’s still a long time but much better than the alternative. Take a mental picture of where we are now, because this is likely the farthest mankind can ever hope to reach in the next thousand or so years. As we zoom out, we stumble into the parts of space that we can only ever hope to see with a telescope. [3]

Above is our interstellar neighborhood, where that bright circle that represents the sun is about 100 times bigger than any distance we’ve ever reached with satellites. Moral of the story, these dots are not to scale, they’re about a billion times larger than the stars they represent. This image is roughly 50 light years across (293,000,000,000,000 miles) There’s a lot of empty space out there, and it’s about to get darker.

Next, we see our galaxy, the Milky Way. Note here that we are not zooming out at the same rate as before. We went from an image that was 50 light years across to one that is now 100,000. [4]

We’ve been zooming out pretty quickly, let’s stop here for a minute and enjoy the view. This encompasses all of the stars that are visible in the night sky without an observatory. This is our home, and there is A LOT more to it than you or I can see. There are estimated to be 100 thousand million (100,000,000,000) stars in our Milky Way galaxy. A lot of those have planets orbiting them similar to our solar system. At 100,000 light years in diameter, with the fastest technology we have today, it would take humans a staggering 166 million years to get from one side to the other. Maybe one day this can be accomplished with generational ships going near the speed of light, or by uploading our minds to computers and sending them along for the ride, or even wormholes that can lead us through the fabric of space time to get to our destinations faster. It would take humans hundreds of thousands, if not millions, of years to colonize our neighborhood of the galaxy. That’s too long for you or me to see it, but the universe has been around for billions of years. This begs the question: if so much time has gone by, why hasn’t someone else done it? And if they have, where are they? Maybe it’s as simple as them being on the other side of the galaxy, or maybe they’re hiding. Maybe they wouldn’t think to talk to us the same way we wouldn’t think to talk to ants. We just aren’t smart enough yet. Whatever the reason is, even this galactic empire pales in comparison to where we’re going next.

Our neighborhood of galaxies is called our local group. This collection of about 30 galaxies is contained in a sphere on the order of 5 million light years. It takes light 5 MILLION years to get from one side to the other. [6]

Next comes clusters and super clusters. Our local group of galaxies is a small part of our local cluster, which is itself a small part of our super cluster. I know. It just keeps going. Every single little dot on the following picture is an entire GALAXY. Some of them being much, much larger than ours. This supercluster is on the scale of hundreds of millions of light years and contains over 100,000 galaxies. [7]

These superclusters are the largest individual “structures” in the universe. Structures in this sense means collections of things. So now you’re thinking, “okay. Superclusters are absolutely massive. Hundreds of millions to billions of light years across. There’s gotta be what, like 5 of these in the universe?”

No. There are estimated to be 10 MILLION superclusters in the observable universe. 10 million superclusters, each with over 100,000 galaxies, each with over 100 thousand million stars. This puts the total number of stars in the observable universe at 1,000,000,000,000,000,000,000 (1 billion trillion). [7] Still don’t think aliens exist? Each of these stars has stuff orbiting them, and in the Milky Way alone there is an estimated 40 billion potentially habitable planets. This puts the odds of life other than ours on Earth existing at, well, essentially 100%. For us to be the only life in just our own galaxy the odds would be 1 in 11 billion. That would be like winning the Powerball lottery 37 times in a row.

This expanse covers about 93 billion light years. Take a moment to remember where we started: New York to LA is 0.013 light seconds. Now we’re here, with this view: [8]

So, what does this all mean? Does this make us and Earth completely meaningless? Or does it make it all the more meaningful? While statistically speaking it’s impossible that we’re alone in the universe, so far, it’s clear that we’re not all that common. Somehow some way we made it over an insurmountable hurdle to transition from star dust, to life. There is inconceivable danger out there, but our little blue orb navigates us safely through it. The best spaceship we’ll ever have.

If you’re interested in getting a better visual representation, I highly recommend this video. As always, thank you for taking this adventure with me. Happy Wednesday.

It's Not Rocket Science

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