Astronomical Driving

Jul 12, 2017

How collectively all the drivers on planet Earth drive more then one light year in distance every year.

While conducting public outreach astronomy programs I sometimes try to relate the scale of astronomical distances to everyday driving which I hope people can relate to better. Unfortunately even these driving distance analogies often end up being just another second order reality. I start by asking folks if they could drive to the Sun at 60 MPH (a mile a minute) just how long would it take with no restroom stops. It is not shocking to know that it would take 93 million minutes. It is somewhat disconcerting to realize that this translates into 176 years of driving.

This just inside our solar system which if defined as 5 light hours (out to Pluto) would take 6,200 years to drive. What about the nearest star or even a light year of distance which is after all the purpose of these driving distance analogies.

There are 270,000 of these 176 year driving distances between us and the nearest star. There are only 63,241 of these 176 year driving distances in a light year. You could divide by ten to work out the driving times in a passenger jet traveling at 600 MPH. That is 47.5 million years and 11.3 million years respectively. That is a long trip without a restroom break, (4.75 and 1.13 million years for our jet airplane).

You can well imagine my surprise when I was reading an article the other day where it was claimed that all the cars on Earth (1.1 billion cars and trucks) travel just over one light year collectively every year. Here I had been using these local astronomical distances as something unimaginable and humans are already collectively driving one light year every year. It is just something I had never given any thought about heretofore.

I wondered, is it even possible, is it true? There are 6 trillion miles in a light year (rounded up) and one billion cars on Earth (rounded down from 1.1 billion) so “YES” it’s entirely possible. All each car would have to manage is 6,000 miles per year to make this happen. We drive our car 12K miles per year, but being an American, living in the desert southwest might account for more than average driving.

Electric drive could really help humanity out with this driving/energy equation. If EV’s are three times more energy efficient than IC cars the universal adoption of electric drive really has the potential to reduce our collective driving energy consumption.

Let’s just say all cars average 25 MPG, that is 6,000/25 = 240 gallons of gas per car per year. That is obviously 240 billion of gas per year. Even EV’s averaging only 75 MPG e would reduce this number to 80 billion gallons of gas equivalent. In point of fact this total energy would end up being somewhat less than that given EV’s get better fuel mileage in the city. Charge all these cars on photovoltaics or wind power and we would have a lot cleaner environment with much more carbon neutral driving.

We are really enjoying our PHEV (2015 Ford C Max Energi) and I have to admit I never imagined just how much better electric drive is until we got one and started driving it as a daily driver. We do about 2/3rds of our driving in EV mode and I am wishing it was more. I actually do not like for the IC engine to come on in our car.

When our pickup truck is paid off in December of 2020 we are planning a move to a pure BEV. If we can we would like to get our hands on a Tesla Model 3 at that time, but who knows what tech, and what kind of deals will be available to us then? I am especially interested in the Tesla charging network which I think is of critical importance to making EV’s viable for the general public. The reason we bought a PHEV last year was because of this unresolved charging infrastructure issue.

We think we could recycle our PHEV to our daughter and son in law at that time to get them into a newer, more fuel efficient vehicle then they would otherwise be likely to afford. We average 60 MPG including electricity and that is significantly better then driving a 30 MPG oil burner. They live closer to town then we do so their potential savings are better than ours.

Owning an EV puts you mentally in a different world then the drivers around you exist in. In the city you are getting over 100 MPG e with no tail pipe emissions. When you pull away from a red light it is with quiet torque and no gear shifting. Instead of “Vroom vroom”, I have wanted to get a bumper sticker that says “Whir, whir”. Unfortunately I don’t like bumper stickers at all. If I even had one it would have to go in the window.

When I was still working, I used to get off work at 11 PM, and in driving home I could often see stars. Being a true blue amateur astronomer I could usually identify the stars I was seeing, even if it was cloudy, and there were only a few stars visible. One star I would often see (Under the arm of the Big Dipper) near the Northwest horizon was Cor Caroli. I would often say to myself “Driving to Cor Caroli”, ought to make a good blog title, but, I never used it.

Cor Caroli is only 115 light years away so it would only take 1.2995 billion years to get there, so what is the problem? Possibly we might want to consider a different drive technology, something that could move us a little faster. In the meantime Electric Drive Technology may just be the ticket for all us Earth bound drivers!

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