We live on a spinning planet. Depending on latitude your individual speed varies from 0 mph at the poles to 1,040 mph (1,674 kph) at the equator. Here at 47 degrees north I'm madly spinning eastward at 710 mph (1,143 kph). Everything else around me is, too. That's terribly fast, but my teacup and radio stay put because we're all moving at the same speed and at rest relative to one another.
This is the same reason items don't go flying around an airplane even though it's jetting across the sky at more than 500 mph. To find out how fast you're traveling enter your latitude into this calculator. Don't know your latitude? Find it here.
One obvious way to get a sense of Earth's rotation is to watch the sun or moon move across the sky. As the planet spins each rises in the east and sets in the west. While useful, their large size make them blunt instruments. Stars are better tools because they're points of light that are quickly covered or uncovered by an obstacle such as a tree branch.
If you carefully line up a star with the top of a tree, building or power pole and stand still and watch, you'll see it move in under a minute. Stars move upward in the eastern sky, from left to right across the south and down in the west, so plan accordingly. For example, if you place a bright star in the eastern sky a smidge below your neighbor's roofline you can watch a dramatic star-rise within a minute. Seeing a star move in near real-time is a quiet thrill, plus it's quick proof we living on a whirling top.
If you have a telescope, point it at a bright star, plunk in a high-magnification eyepiece and you'll see that sucker move in a only a few seconds. Telescopes don't just magnify things but also the Earth's rotation.
What about revolution, our globe's yearly dance around the sun? Earth scoots along its orbit at an average speed of about 66,600 miles an hour (30 kilometers per second), fast enough to move its own diameter in just 7 minutes. Watching the constellations slowly drift from east to west — with one season's constellations replacing another's — is one way to get a sense of the planet's orbital motion. You could also track how the sun climbs higher in the southern sky as winter melts into spring.
Those methods are fine but hardly provide a visceral sense of a planet on the move. For that you'll need to observe a meteor shower or, if no shower is currently active, watch for random meteors, called sporadics, after midnight.
During a meteor shower the Earth moves directly across a stream of meteoroids, which are mostly sand-sized particles sloughed off by comets and asteroids. When we plow into the debris it strikes the atmosphere and heats up, producing meteors. You can actually sense how fast the Earth is traveling as multiple meteors streak from the shower's radiant right before your eyes. It's exactly analogous to snow or rain streaming across your windshield from a point in the distance when you drive through a storm.
The next major meteor shower, the Lyrids, occurs the night of April 21-22 — a long wait! But you can still experience the feeling of zipping through space if you watch for sporadic meteors especially after midnight when the part of the Earth you're living on turns into the direction of planet's motion. From midnight until dawn we meet most stray meteoroids head-on whereas before midnight most have to catch up with the planet. Typically five to eight sporadics per hour are visible after midnight compared to two to four during evening hours.
The ultimate sensation of motion would be to experience rotation and revolution simultaneously. For that you'd have to be lucky enough to watch a star reappear from behind a tree branch at the same time a meteor streaks across the sky. Just thinking about it makes me dizzy!
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.
