Buckle Up For The Cosmic Roller Coaster Ride Of Your Life

Water creates a chaos of shapes as it splatters into the air after striking a rock in a nearby creek. Photo: Bob King

Last week I watched water racing down a creek slam up against a boulder and break into a frothy spray of droplets and blobs.  My eyes struggled  to make sense of it. The camera proved a far better instrument to dissect the spray into a series of moments, so I could better appreciate the water’s ephemeral shapes and patterns.

We can stop movement and hold time still for a moment, but that’s all. You and I and everything around us are in constant motion. Take the rotation of the Earth. As I type, my keyboard, home, and the entire city of Duluth, Minn. are all moving together at 708 miles per hour toward the east. Speed varies according to latitude, ranging from 0 mph at the poles to 1,041 at the equator. Folks in Nome, Alaska are traveling at 455 mph on the merry-go-round, while those in Los Angeles zip along at 860 mph.

Depending on your latitude, the speed with which your rotation speed varies. Close to the poles, it's slow because you turn through a very tiny circle in 24 hours. At the equator, you have travel the entire circumference of the Earth in the same time. Illustration: Bob King

The reason rockets are launched in Florida and not North Dakota is because Florida is closer to the equator, giving them a 250 mph edge compared to Fargo as they head into orbit.

To determine how fast you’re moving, multiply Earth’s circumference times the cosine of your latitude and divide by 24 hours like this: 24,902 mph x cos (latitude) / 24 hours. Cosines are easily found by heading over to the handy Cosine Calculator and keying in your latitude. With that number in hand, use your computer’s calculator to arrive at your personal velocity.

We travel nearly 67,000 miles per hour in our yearly orbit around the sun. Illustration: Bob King

Spinning is just one of Earth’s several motions. We’re also orbiting the sun at 18.5 miles per second or nearly 67,000 miles per hour. At that speed our planet traverses 600 million miles in one year. Since Earth’s about 8,000 miles in diameter, it moves about 202 times its own size in one day. Even sitting still we’re putting on miles at a fantastic rate. Live till you’re 80 years old and you’ll  have 48 billion frequent orbital-flyer miles to show for it.

Destination Vega! The sun and solar system are moving the general direction of the bright star Vega in the constellation Lyra. Photo: Bob King

So far we’ve only talked about Earth, but the sun isn’t standing still either. Our star is one of several hundred billion stars in the Milky Way galaxy, all of which are moving. Based on studies of the motions of stars in our neighborhood, astronomers have determined that the sun hauls it family of planets, comets and asteroids at 43,000 miles per hour in roughly the direction of the bright star Vega in Lyra.

In the course of a  lifetime we will have moved 40 billion miles closer to the star. Unfortunately that huge figure will hardly begin to close the gap between the two stars. Vega is not only 25 light years away (150 trillion miles), but it’s not standing still either. If you’d like to see where we’re headed, face northeast around 11 o’clock the next clear night. The bright, twinkling star low in the sky is Vega.

The sun circles the galactic center once about every 225 million years traveling at 483,000 mph. Illustration: ESO with additions

If you guessed that we’re not quite finished yet, you’re right. The Milky Way is a gigantic starry pinwheel, where the speeds of stars vary with distance from its center the same as the speed of a planet varies with its distance from the sun. The spinning of the galaxy carries the sun and neighboring stars around the galactic center at 483,000 mph or nearly 7 times faster than Earth orbits the sun.

Good thing the sun is holding onto us or we’d soon be lost among the stars like change dropped from a pocket. Our solar system is located about 2/3 the way from galaxy’s center to its edge and takes 225 million years to complete one orbit. Each year we celebrate our birthday after completing another cycle around the sun. Since the sun and planets first formed 4.6 billion years ago, the sun has orbited the galactic center 20 times, making it 20 galactic years old. Hey, that means in another 225 million years it will finally come of age!

Watch out for what the future brings - Andromeda and the Milky Way will one day be one galaxy sometimes referred to as "Milkomeda". Other members of the Local Group are labeled. Credit: Andrew Colvin

The Milky Way is one of more than 50 galaxies in a small cluster of galaxies called the Local Group. Ours and the Andromeda Galaxy, located 2.5 million light years away in the constellation Andromeda, are the group’s two biggest members. As if we weren’t moving in enough ways, these two galactic behemoths are hurtling toward one another at 50 miles per second or 270,000 mph.

2.5 billion years from now we’ll collide in a spectacular display of fireworks as merging gas clouds fire up brand new clusters of stars. Over time, the two spiral galaxies will evolve into one much larger elliptical galaxy some like to call “Milkomeda” (milk-AH-meh-duh).

The Local Group is one of many galaxy clusters belonging to one vast assemblage of clusters named the Virgo Supercluster centered in the constellation Virgo. Credit: Andrew Colvin

The Local Group is a small cluster on the outskirts of the much larger Virgo Supercluster of galaxies. Consider Virgo as downtown New York and our gang as a small town in the boondocks. Like my daughters, who are drawn to the dazzle and glitter of the big city, the Local Group is falling at more than half a million miles an hour toward the center of the Supercluster.

Still not dizzy yet? Let’s take one final step and put the pedal to the metal.

Relative to the cosmic background radiation – the ever-expanding , steadily cooling energy left over from the Big Bang that permeates all of space – the Milky Way galaxy is moving at the amazing rate of 1.3 million miles per hour roughly in the direction of Leo and Virgo. The reason for our great haste? New space created between the galaxies as the universe expands causes them to appear to rush apart from each other. The Local Group holds together through the combined gravitation attraction of its members, but when you take in the bigger scene, galaxies have been rushing away from each other at alarming speeds since the Big Bang 13.75 billion years ago.

OK, even I need a little help at this point, so let’s sum up:

* We’re rotating around 700-800 mph depending on latitude.
* Orbiting the sun at 67,000 mph
* Traveling among the nearby stars at 43,000 mph
* Orbiting the center of the Milky Way at 483,000 mph
* Moving toward Andromeda at 270,000 mph
* Diving into the core of the Virgo Supercluster at 540,000 mph
* Riding aboard the Milky Way in the expanding universe at 1,300,000 mph

And yet, in spite of all the whirl and flow, we can still find quiet moments under a dark sky to contemplate it all.

A portion of the Hubble Deep Field photograph showing a multitude of galaxies. The space between each galaxy grows larger with time as the universe continues its expansive ways since the Big Bang about 14 billion years ago. Credit: NASA/ESA

25 Responses

  1. Patti

    Awesome post (even though my head is still spinning). I read your blog daily and find it enjoyable and informative. Thank you!

    1. astrobob

      Hey MBZ – many thanks! I’ll see if I can work the Triplet in there soon. It’s a great little group for a small scope. I appreciated the suggestion.

  2. Lynn

    Hi Bob, thanks for that wonderful post taught me a thing or two, i’m still dizzy 🙂 keep up the good work you do a great job and I always look forward to reading your posts every night it amazes me that so much goes on outside our world and there is so much still to learn 🙂

  3. Stephan

    Hi Bob !
    wow, what a journey, from the small and local to the vast and cosmological. Thanks a lot for the article! I just love reading your blog.

  4. Travis Kitch

    Hi Bob,

    Let’s not forget that plate techtonics are constantly moving us around as well! Fasten your seatbelt.


    1. astrobob

      Ha! Thanks Travis. And don’t forget that every molecule in your body is vibrating at an incredible rate. It never stops!

      1. Travis Kitch

        What is it that is preventing us from feeling these speedy effects on earth? Is it the atmosphere, the gravity of the planet, the magnetism? In other words, what keeps our hair from blowing in the cosmic wind?

        1. astrobob

          It’s like being in an airplane. Relative to the ground, you’re traveling at 500 mph, but since everything in your immediate environment is also moving at 500 mph, all is at rest. If the Earth’s were to somehow stop rotating or change it rotation rate suddenly, every building and person would be uprooted, fly off, crash and be destroyed. As for Earth moving through space, there’s no “wind” to feel, and as long as there are no sudden lurches in our orbital speed, we’re totally unaware of moving. An elevator is a good example. As elevator travels at a constant speed between floors, you hear a hum but can’t really feel you’re moving since everything’s moving with you. Once you stop or accelerate upward or downward, you very aware of the motion. Einstein made much of this in his Relativity Theory, pointing out that there’s really no distinguishing between acceleration and gravity.

    1. astrobob

      Thanks very much Sue. I’ve always enjoyed the Galaxy Song. Long ago, another teacher and I sung in front of our class together.

  5. Chad Waters

    Would our speed be constant or are there variations in speed similar to being on the tea cups ride? If you spin, and orbit at some point your direction of spin is in the opposite direction of orbit, right? On the outside of all of these turns you would move faster than on the inside?

    1. astrobob

      Nice question Chad. Our spin is constant (or nearly so factoring out tiny variations caused by earthquakes, etc.) however our orbital speed varies slightly in a regular pattern as we swing from perihelion (closest approach to the sun) in January to aphelion (farthest) in July and back again. Earth spins counterclockwise as seen from over the North Pole. This is the same direction in which we travel around the sun.

      1. Chad Waters

        Excellent. Rereading my post maybe I can clarify. The direction of spin doesn’t change, Haha I’m not a 2012’er, but similar to perihelion and aphelion, can you apply the same concept to the rest of the universe and beyond? We move faster through the cosmos at night because we are further from center (Sun); faster in winter and depending on where we are in the Milky Way and again in Andromeda. (Scribble all that out) the picture above (Sun in the foreground Earth in the back) earth is moving Left at a constant speed. Miami is moving right, slower during the day in relation to the Sun. At night Miami will travel forward through the cosmos faster than during the day. Does this effect happen on the larger scale involving the Milky Way and Andromeda? I apoligize for my ridiculous thought process.

        1. astrobob

          No, we don’t move faster at night because our spin is constant and the variation in orbital speed over 24 hours is negligible. Since Miami and all the other cities and places on Earth are part of the planet and not independent of it, no individual city changes speed during the night vs. the day. Likewise it makes no difference in regard to revolving about the center of the Milky Way. However, the speed of rotation varies with longitude, so that in Miami you’re traveling faster than I am in Duluth because you’re closer to the equator. It’s like runners on a track; they’re staggered at different spots because the inner lanes are a shorter distance around the center than the outer lanes. We move more slowly in Duluth because the circle (lane) we travel during one full rotation is shorter than the lane Miamians travel. The longest lane is the equator and the speed of rotation is fastest there – about 1000 mph vs. 708 mph for Duluth, Minn. Of course all these varying speeds mean we all stay in our same places relative to one another. No city can “get ahead” or “fall behind” another.

          1. Chad Waters

            Heh, my wife just read that over my shoulder and laughed at how thick I am being. I totally appreciate your patience. Last time I promise, If you put a finger on either side of a basketball representing two cities on Earth and rotated it counterclockwise and walked towards the wall, would, at some point one finger move towards the wall faster than the other, knowing the entire ball is traveling at one speed? I think this is the “negligable” part you were speaking of, but if it magnified the way the rest of our speed through the cosmos does, it seems it could be substantial if all the stars align… I do apoligize for being dim and unable to convey a thought. Thank you so much for this site that I enjoy so much.

          2. astrobob

            Hi Chad,
            Yes! The finger rotating in the direction of the wall would be moving toward the wall faster than a finger on the opposite side of the globe. That finger would be moving AWAY from the wall. These speeds would reverse as you continued to rotate the ball while somehow still keeping both fingers on opposite sides. OK, so if we make the ball the Earth and the fingers Miami and Tokyo, Miami would be moving away from the sun at sunset while Tokyo would be approaching the sun. This would reverse at sunrise for Miami (and sunset for Tokyo) and cycle on endlessly. It’s a repeating pattern that does not add up to any net speed in a particular direction. Good thing or Miami would tear apart from the Earth! Does this help? If not, ask away.

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