Driving in a Snowstorm After Watching Star Wars
You’re stuck driving through a snowstorm at night. You can barely see anything and you’re stressed out.
You’re gripping the wheel and you can’t even listen to a podcast because you wouldn’t be able to concentrate. Giant snowflakes are whipping towards you and you have tunnel vision focusing on the road just in front of you.
There’s only one thing to do at this point, and we’ve all done it.
You’re suddenly not driving through a blizzard, but you’re the Millennium Falcon blasting through the galaxy in hyperspace.
All it takes is one viewing of that famous scene for it to be forever ingrained in your brain, and for it to inevitably surface as soon as the snow starts flying at your windshield.
But how realistic is this scenario? Let’s ignore the fact that we are literally pretending that snowflakes are stars and that our car is a spaceship. I want to know, if our car really was the Millennium Falcon going full speed through the Milky Way, would it look anything like what we see out of our windshield in a snowstorm?
Let’s ask a few questions before we can get to the bottom of how to have the most realistic fantasy we can.
How fast is our ship?
The first problem that comes to mind is how fast the snowflakes are flying by. If we are pretending those are stars, it just seems this thought experiment is a nonstarter. Nothing can go faster than light, and it would take more than four years for light to travel from the Sun to our closest star, Alpha Centauri. In other words, if our car could break all the rules of physics and actually go the speed of light, it would take four years to see a single snowflake. That doesn’t work.
Lucky for us, we get to use Star Wars logic. George Lucas said “screw physics, I want to tell a good story!” He needed his characters to get from point A to B quickly, the immense distances in space be damned.
If you look at what the estimated speed of the Millennium Falcon is when it does its famous jump in hyperspace, it’s actually kind of silly.
In this in-depth, math-laden thought experiment on how fast the Millennium Falcon actually goes, we get the eye popping result of about 25,000 light years per day, or 1,042 light years per hour. That means you could travel across our 100 billion star and 100,000 light year width Milky Way Galaxy in just four days! So this makes it feel like it might be plenty of speed to allow our thought experiment to remain on track.
How many snowflakes are visible while driving?
So we have the speed we are going, but would we be seeing as many stars zoom by in the real galaxy as we do driving in our car? We next need to figure out how many snowflakes we are seeing during a heavy snowstorm.
A good starting point would be knowing how much snow is in any volume of space at a given moment. Someone did the math on Reddit and there is about 1,000 snowflakes in one cubic meter of air during a heavy snowfall.
Now let’s make some assumptions about our drive through the snow. This heavy snowfall is at night, and you are stressed out and have a bit of tunnel vision as you focus on the road. Your visibility is severely limited, so let’s assume that the space that you can truly focus on is about three cubic meters stacked left to right not far in front of your windshield. You are driving on the highway, but you’re only able to drive about 40mph, which is 64 km/h or 64,000 meters in one hour. So in one minute, you are going 1,067 meters, and in one second, you are traveling six meters.
According to the Reddit math above, snow only falls around half a meter per second, and we are moving forward six meters a second, so let’s just ignore the falling motion and consider the snow stationary for our purposes.
So in one second, you move through a space of six meters forward and three meters wide. In other words, in one second, 18 square meters of snow are visible to you, or around 18,000 snowflakes per second.
If we take that number and multiply it by 60 seconds to get a minute and by 60 minutes to get an hour, we end up with around 64,800,000 snowflakes during an hour long drive.
The low end estimate for stars in our galaxy is about 100 billion, so we would experience less than .1% of the stars in our galaxy during this drive. Even without worrying about if this matches anything to do with the Millennium Falcon, it’s interesting to know it would take 64 days of driving through a terrible snowstorm to see the same amount of snowflakes as there are stars in our galaxy.
The last piece of the puzzle is to think through if zipping by 1,000 snowflakes per cubic meter translates into the actual density of stars while using a Star Wars hyperdrive engine.
How densely packed is our galaxy with stars? According to these lecture notes, the very middle of our galactic core has about 10 million stars per cubic parsec, and near our solar system there is only an average of .2 stars per cubic parsec. A cubic parsec is a giant cube that is 3.26 light years by 3.26 light years and is the terminology astronomers use at this scale.
Using the above calculated speed of the Millennium Falcon, we can figure out that it can travel about .09 parsecs per second. Let’s just round that to a tenth of a parsec. That means it takes about ten seconds to travel one parsec in our Millennium Falcon.
Now we can pretend that each cubic meter of snow visible from the car is actually a .1 by .1 parsec cube (let’s call these mini cubic parsecs). So while looking out our car windshield, each cubic meter of space is now really a mini cubic parsec. Along that logic and to make this all work, we need each mini cubic parsec to have 1,000 stars in it, just like there are 1,000 snowflakes in each cubic meter.
We need to figure out if there is a region of space that fits this description and really has about 1,000 stars in each mini cubic parsec. Astronomers do everything at this scale at full cubic parsecs, so we can do math to figure out that it would take 1,000 of our mini cubic parsecs to fill a full cubic parsec. If we take 1,000 of our mini cubic parsecs that each have 1,000 stars in it, we would need a region of space that has one million stars per cubic parsec to continue making this all work.
We know this is actually possible, because the most dense regions of our galaxy have about 10 million stars per cubic parsec, so we just need be a little further out than the very middle in order to be in a region that has one million stars per cubic parsec and therefore 1,000 stars per mini cubic parsec.
So there you have it. The three main take aways are:
1) If you are driving at night through a blizzard, you are seeing about 18,000 snowflakes a second.
2) If you are pretending to be the Millennium Falcon (which of course you are), it is entirely possible to be passing stars at the same density and rate as you see snowflakes.
3) As a low estimate, it would take well over two months of non-stop driving through a snowstorm to see as many snowflakes as there are stars in the Milky Way.
Thank you George Lucas for not being as much of a stickler on the rules of physics as those Star Trek guys.