Pale Blue Dot

Sometime in the first half of 1990, as the Voyager 1 spacecraft hurtled beyond the edge of our planetary system, it spun around to take one final photo of the place from whence it had come, perhaps never to return again. Actually, Voyager 1 took several images in an attempt to capture a snapshot of the entire planetary system as each world orbits the sun. One of these pictures in particular, however, stands out as perhaps one of the most awe-inspiring and humbling images ever captured in the entirety of human civilization. It was entitled "Pale Blue Dot" by the man who campaigned to have the picture taken and who, in 1980, formally introduced the world to the "Cosmos". That man was Carl Sagan, astronomer, author and arguably the greatest contributor to our common understanding of the universe in modern history.

Sagan's words reflecting upon the significance of the "Pale Blue Dot" have been quoted and paraphrased many times. One wonders if it could ever be said better than this:

"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam."

The sheer sense of humility inspired by such musings is chilling, and yet we should also be reminded of what we don't see beyond the confines of that photo. The image shows us as a part of the much larger grandeur of the universe. Granted, it is a very small part, but it is still a part. Carl Sagan also said, "We are a way for the universe to know itself," and while the universe may not have planned us for this purpose, or even planned us at all, I think we should rise to that challenge. This picture of a minuscule Earth sparkling in a ray of light is just a glimpse of the amazing perspectives that await us as we strive to meet that challenge.

To know the universe is a pretty enormous undertaking. We're making some strides, but we still have quite a way to go. Voyager 1 was launched in 1977 and took about 12.5 years to travel to a point where it would be about 6.1 billion kilometers from Earth, the distance from which the "Pale Blue Dot" photo was taken. A distance of 6.1 billion km is pretty far when you consider the distances we typically travel on the Earth, but on a universal scale, it isn't even a drop in the bucket.

Consider these points:

The universe was recently estimated to be 156 billion light years wide. As many of you probably know by now, a light year is the distance light travels in a single Earth year. Since light moves incredibly fast (a bit under 300 million meters a second), to say 156 billion light years definitely sounds like a lot, but words like "light year" and "billion" are simply words that we use to make it more convenient to talk about distances and numbers most humans couldn't even imagine. For the sake of demonstration, I am going to try to stop using these words to give you a little better idea of how mind boggling these numbers really are. My standard measurements will be in kilometers (km) and meters (m), admittedly abstractions themselves.

If the universe is 156 billion light years wide and there are (get ready) 9,500,000,000,000 (that's 9.5 trillion!) kilometers in just one light year, that means that the universe is 1,482,000,000,000,000,000,000,000 (1.5 septillion) km wide! Looking at the distance at which the "Pale Blue Dot" was taken, which was probably about 6,054,558,968 km (give or take a few million km), we can do some simple math to figure out how that compares to the universe.

*doing calculations*

That means that the distance at which Voyager 1 snapped that picture was 1/242,950,819,672,131^th of the total diameter of the universe. To put that into perspective, if the width of the universe were 1 meter, the distance from Voyager 1 to the Earth in 1990 would be about .00000000000000412 meters. The shorthand for this tiny distance is 4.12 femtometers, which is about the diameter of an atomic nucleus (depending on the atom). This calculation, comparatively, reduces the Earth to a size smaller than a proton or neutron, probably smaller even than a quark.

While this comparison seems to relegate us to some insignificant proportion of the universe, that's only true looking down on this tiny blue speck from afar. If we instead look outward at the vast reaches of our universe, we see that there is so much yet to discover. We are travelers on a quest to answer every question that can be conceived. The universe offers us no shortage of opportunities to drive and satisfy our uniquely human brand of curiosity.

It's not going to be easy. Many things stand in our way, the most perplexing being the universal speed limit, the speed of light. Even significant fractions of the speed of light seem difficult to fathom given our understanding of relativistic speeds and the current level of our space travel technology. Even at the relatively impressive speed that Voyager 1 shoots out of our solar system, it is still only moving at 1/18,000^th the speed of light. We're going to have to come up with something a lot faster than that if we're going to explore even the closest corners of our interstellar neighborhood. I believe, however, that we are propelled by such an intense need to know, we will find some way to overcome these obstacles. Far in the future, when the intelligent descendants of the human species look back on this pale blue dot, I hope they will look on it with fondness as the starting point of the incredible journey that brought them to every corner of the galaxy and maybe, just maybe, to their first steps into the larger universe.