Light Years for Dummies, Redux

How long is a light year

We regularly sentence... err, assign an intern to check the source material for our DotD nominations, in particular making certain that the original hasn't been deleted (or, in the case of Leaf Group, rewritten). One such check not long ago led us to a Sciencing.com article we'd long had in our files as a potential nominee, something called "Distances of the Planets from the Sun in Light Years" by Colby Phillips. The English major had compiled a list of distances, carrying out the distances to twenty-one friggin' decimal places! But have no fear; Leaf Group assigned cleanup team member Rachelle Dragani to "fix" it...

And it definitely needed fixing, considering that Phillips had defined a light year as a big distance by telling us that "a mile is 1.70111428 --- 10-13 light years," thereby making it clear to all viewers that he had no idea how scientific notation works. Dragani fixed that, so to speak, by explaining that,

"...a light year conveys time more than it does actual distance. For instance, if you are running late to meet a friend, you might say, 'I’m 20 minutes away,' instead of 'I’m 3.2 miles away.'"

Our freelancer fell victim to conflation, somehow deciding that "if you see a photo of a galaxy that is 90 million light years away, you’re actually getting a glimpse of what that galaxy looked like 90 million years ago..." ...means that light years are a measure of time. Idiot. Whatever the case, once Dragani had gotten that bit of scientific ignorance out of the way, she merely copied Phillips' version of the distances between the sun and planets (omitting the now-disgraced Pluto) and reworded the text slightly to avoid plagiarism. Here's an example of a planet's average distance from the Solar System's primary: "Jupiter: 0.00008233217279125351 light years, or about 43 light minutes away from the sun."

We don't know about others, but we're a darned sight more likely to convey that information in scientific notation (a concept that appear to have escaped both Dragani and Phillips), rendering the average radius of Jupiter's orbit as 8.233 E-05 or, perhaps 8.233 x 10^-5 light years¹. But that's just us. A lot of us are scientists, though, so we understand what that means: it means 0.00008233, but that's way too many leading zeroes.

Then again, none of us publish freelance posts on topics about which we know squat, so we couldn't be – unlike Rachelle – today's Dumbass of the Day.

¹ In reality, Jupiter appears to be 8.214 x 10^-5 light years from the Sun, but who knows where Phillips got his data...

copyright © 2019-2021 scmrak

SI - ASTRONOMY