I Feel the Earth Move

 Post by Lara

26 June 2013

I was a camp counselor during the summer of 2007 and during that time I had the extreme pleasure of helping out with nocturnal camp, which included a trip to a local observatory late one night to view star clusters, nebulae, and other fun cosmic visions.  That experience got me excited about astronomy, and resulted in Kevin buying me a Night Sky Atlas and a green laser pointer (the kind you can point into the sky!) one year for my birthday.  Sadly, the hustle and bustle of life in the states meant that I only pulled out the atlas a handful of times in the years after, but it made it onto our packing list for Peace Corps.

Back before we moved to Salone, I expected that the night sky would be a bit different here than it was in Ohio where we came from.  I recall noticing some differences when I lived in Ireland for a semester in undergrad—first, that the difference between the longest and shortest day of the year is noticeably more extreme than in Ohio (when I got to Galway in January, the sun was rising around 8:40am and setting by 4:20pm, and when I left the sun was coming up around 5 am and setting around 9:20 pm).  I don’t really recall the moon and stars looking very different, but if anything I guess I would have seen fewer of the southern constellations.  So, I expected some differences in the night sky, but I didn’t really know what kind of differences I might note. 

The first thing we noticed about the night sky was that the moon has rotated—the man in the moon is kind of looking down, and the crescent moon looks like a cup.  The first few weeks we spent here, we were really off-put by the fact that the moon seemed to have jumped and turned from where it ought to be, but like most other things here, we got used to it.  Also, because city lights are just not nearly the same thing here, the lack of light pollution means that the stars are so much more visible than they were in our suburban hometown, and we can actually see pretty clearly by the light of the full moon.  We also immediately noticed that we could see constellations we’d never seen before—our favorite is Scorpius, which spends a lot of time taking up a big portion of the sky from May or June until October or so (as I recall). 

The next thing we noticed took a little longer, but became apparent as we spent time studying the Night Sky Atlas and learning the names of different constellations, stars, and planets we could see—the stars were shifting in the sky really quickly.  As in, I could look at the sky and see the Big Dipper standing on its bowl between the trees behind my house, then go inside for a few minutes or make a cup of tea and come back to the same spot, and the big dipper was now leaning over and only half-visible in our heavily-treed back yard.  I could swear that if I just sat watching the sky, I could see the stars slowly shifting.  Where we come from, those kinds of shifts happen over the course of some hours, not minutes.  It was so jarring to me that I wasn’t sure it was real.

Until—I read Bill Bryson’s A Short History of Nearly Everything, which is an awesome book that you should all go buy and read (I recommend the Special Illustrated Edition if you can get your hands on it).  The book’s basic goal is to give some background and context to all those “facts” we learn in school or from the media, such as the temperature of the core of the Earth or the movement of electrons in atomic orbitals, that might make us wonder how on Earth did anyone figure that out?  The book is a wonderful read—informative, witty in that British tongue-in-cheek way, and not so high-brow that it becomes boring.  Bryson managed to answer a whole lot of questions I’ve had through the years and give me what I would consider to be a respectable basic knowledge of everything from geology and paleontology to particle physics and microbiology.  It was on page 67 of the illustrated edition, in the asterisked comment at the bottom of the page, that Bill Bryson confirmed my suspicions.  “How fast you are spinning depends on where you are.  The speed of the Earth’s spin varies from something over 1,600 kilometres an hour at the equator to zero at the poles.  In London the speed is 998 kilometres an hour.” 

So, there it is—making the trek from Ohio to Sierra Leone meant increasing the speed of the Earth’s spin below me from about 777 miles per hour to a whopping 989 mph, and it’s a difference you can almost feel here.  I love sitting outside at night and taking note of the orientation of the stars, then waiting just a little while and looking back to see that Scorpius’s tail is now disappearing over the horizon.  It’s just one more very different thing I get to enjoy during my two years here.

I did a lot of web-searching in writing this post. Special thanks to timeanddate.com, Bryan Gastonguay for introducing us to Stellarium (www.stellarium.org), NASA’s Goddard Space Flight Center’s web page (http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970401c.html), Google, and of course, Bill Bryson for all the information!

This post is dedicated to my favorite bald astronomer, Jason Heaton.