Light-Seconds

April 7th, 2011

This is Victoria Crater, on Mars.

I put it up there because I think it’s beautiful and also because it made me start thinking about distances, especially astronomical distances.  If you just yawned, stop reading.

Most of us probably think of the Victoria Crater, if we do at all, as being somewhat remote, since it’s on another planet and all.  But comparatively speaking, it’s not even on the next block, or in the back yard.  It’s on first inch of the top step outside the back door.

This blue globe we share is 93 million miles from the sun. That’s a big number to us, but it’s weensy, astronomically speaking.  Miles are far too tiny to use for astronomy.   So astronomers use the light year as their basic unit of distance.  The light year is the distance light travels in a year — 186,000 miles per second, times sixty seconds per minute, times sixty minutes per hour, times 24 hours per day, times 365 days.  Roughly, six trillion miles.  That’s six thousand thousand million miles. As in 6,000,000,000,000.

At 93 million miles away, the sun is our local star.  It takes the sun’s light about eight minutes to cover that distance and reach us.  (In other words, the sun actually comes up eight minutes before we see it and  actually goes down while, to our eyes, it’s still comfortably above the horizon.)

Here’s the distance between us and Mars, expressed in similar terms.  If the Earth were a source of light, earthlight would reach Mars in three minutes and two seconds.

So, Earth to sun, eight light minutes.  Earth to Mars, three light minutes.

The closest star to earth (other than the sun) is Alpha Centauri, which is an exotic little object that owes a lot of its brightness to the fact that it’s actually three stars orbiting each other.  (This happens all over the place; some astronomers believe that most stars are in pairs and trios.)  The nearest of the three to us, Proxima Centauri, is 4.2 light years away.  Earth to sun, eight light minutes. Earth to closest star, four-point-two light years.  Oh, yeah: Earth to Mars, three light minutes.

One of the earliest questions asked by astronomers was, What’s close and what’s far?  Everybody figured out pretty soon that brightness wasn’t much help.  There are dim objects near us and bright objects that are far away.  So how to tell?

The first idea, and it was brilliant, was to use parallax.  Put your finger about ten inches in front of your eyes, and focus on something farther away.  Close one eye and then open that eye and close the other.  See how your finger jumps back and forth, while the more distant object remains relatively still?  Early astronomers used the extremes of the earth’s orbit as “eyes,” sighting the same areas of the sky six months apart to see which stars “jumped.”  Those would be closer, right?

Okay, remember, the sun is about 93 million miles from the earth.  That means that the “eye” that was open in June was 186 million miles away from the “eye” that was open in December.  The eyes were 186 million miles apart.

And almost nothing moved.  Everything was too far away.

This was one of the pieces of data that drove the last nail into the coffin of the Copernican universe, with the sun at its center.  If the stars were so far away they didn’t jump at two blinks 186 million miles apart, odds were pretty good they weren’t orbiting the sun.

Until the 1920s, we thought all the stars in the universe were — well, stars, all of them in the Milky Way Galaxy. Some of them, kind of fuzzy-looking, were called nebulas or, more properly, nebulae. And then the 100-inch Hooker telescope was put in place on Mount Wilson, and Edwin Hubble looked through it.  And it was immediately apparent that the nebulae weren’t individual  stars.  They were enormous disks, or pinwheels, or globes, or amorphous straggles, of stars.  We saw them as little smears of light because they were so far away.

Through the Hooker, Hubbell also saw that some of the hard, bright pinpoint stars were also huge structures of stars — galaxies.  And he and his team saw that many of these galaxies contained stars identical to some that also burned much closer to us — stars that brighten and dim and are therefore called variables (cepheid variables, actually).

This was important, because the scientists knew that there was an absolute relationship between how long it took a variable to go from bright to dark, and how bright it actually was.  Unlike most stars, which might be bright and far away and dim but close, you could deduce exactly how bright a cepheid variable was by timing its brightening and dimming.  So they did the math and measured the brightness and figured out how far away those variable stars would have to be to appear that dim —

And instantly increased the estimated size of the universe ten thousandfold.

We now know that the universe is millions of times larger than Hubble thought, that it contains billions of galaxies, each made up of billions of stars, all hurtling away from each other at almost unimaginable speed, some of them apparently drawn toward even larger objects and clusters of structures, such as The Great Attractor.  We’ve peered across these tens of billions of light years and back through billions of years in time until we can see, at the edge of our vision, almost to what astronomers call The End of Greatness, the point in astronomical history beyond which galaxies had just begun to form and the distribution of matter was smoother and less “lumpy”” with structures.

All this amazes me, but nothing amazes me more than the fact that these computations began, in part, with a blink of two human eyes, the pupils of which are three or four inches apart, and that all the information, calculation, and inspiration that’s followed was stored, processed, and generated in an organ that’s about six inches long and three pounds in weight.  And is resolutely, and so far as we know, permanently, earthbound.

16 Responses to “Light-Seconds”

  1. Gary Says:

    As every pious believer knows, the reason the stars show no devilish parallax is that they are all in the same plane on a crystal sphere – surrounding the earth at the CENTER of the universe.

    So of course there isn’t any parallax.

    Besides, even if there were any of your wicked parallaxes, as the godly Francesco Sizi so wisely stated more than four hundred years ago: they are invisible to the naked eye and therefore can have no influence on the earth and therefore would be useless and therefore do not exist.

    Humbug, I say. Humbug!

  2. EverettK Says:

    That picture of Victoria Crater from orbit is one of my favorite Mars pictures (along with many of the great pictures taken from the surface by Opportunity).

    Stellar and intergalactic distances can truly “put us in our place,” infinitesimal motes of dust stuck to a tiny grain of sand adrift in the universe.

    That’s assuming we can even grasp the numbers and distances involved. Gotta love it!

    (But what’s a mystery writer doing hanging out with the science geeks???)

  3. Usman Says:

    LOL @ Gary. Exactly, Humbug.
    Tim is misguiding us all to, well, let’s put in literary terms–Dante’s Inferno.

    I sense a sci-fi coming up. Is Poke going into space? Is Junior going to trace aliens and end up saving the universe?

    Either way, loved reading this and knowing how little we know.

  4. Dana King Says:

    I love this stuff. I never feel more a part of the universe around me than I am made to feel tiny, such as watching the last full moon, with the moon and earth as close as they get, or even a thunderstorm. If more people took the time to accept our true significance in the universe, or even the planet, we’d have a much better universe to live in.

  5. John Lindquist Says:

    Mystery writers may solve the mysteries that scientists fail to get their minds around.

  6. Patg Says:

    Love the blog comments and pictures. I have one of one galaxy ‘blowing’ through another that I like to gaze at.
    Civilizations could have come and gone in the blown through one and hardly notice, time and space being what it is.
    Gain of sand? Our planet? More like the Milky Way is the grain of sand.
    I love these distances, they really does put all the mindless belief we indulge in into perspective.
    Thanks.
    Another mystery writer
    Patg

  7. Timothy Hallinan Says:

    What a cosmic crew.

    Except, of course, for Gary and his disciple Usman. I’ve always been partial to the transparent spheres models of the universe myself — they solved so many observational problems, back when observation was done with the naked eys. (It amazes me how much stuff people figured out without telescopes.) I’d love to get a good model of that universe — someone must make one, and if not, well, hey, Gary – a business for you. Universes R Us, 3-D models in various sizes of different concepts of the universe. I’ll buy in advance the transparent spheres and the “turtles all the way down” models. Coffee-table size, preferably.

    Usman, I’d also buy a model of Dante’s Circles, especially if it had tiny action figures in it that we could manipulate into different positions representing agony. Dante wrote the Purgatorio and Paradisio, too, but all anyone wants to talk about is the Inferno, which is a problem we much lesser writers face, too, all these centuries later. How not to let the villains dominate the book. (Look what happened to Thomas Harris — abandoning Starling for an increasingly cartoonish Hannibal.)

    But no, Usman, no science fiction on the horizon. One of the first “big” nonfiction books I ever read was THE MYSTERIOUS UNIVERSE, by Sir James Jeans, one of those scientists the Brits sometimes turn out who can make words sing. The universe he was describing was a 1940s model, much less strange than the one that confronts us today, but plenty strange and plenty beautiful for me. I’ve been reading astronomy and cosmology ever since.

    And for those of you who have found your way into the 21st century:

    Everett, if someone had asked me on pain of death if I got the answer wrong, which member of the club would have favorite Mars pictures, I’d have chosen you without a moment’s hesitation. This image actually prompted this blog, just as the image of the woods inspired the last one. I think I might go with beautiful images for a while. Or maybe not. Don’t know whether you’ve seen the “Dragon” on Mars — a deep and therefore dark canyon shaped just like a dragon — it’s phenomenally beautiful.

    I like Mars because it’s like Earth’s first cousin — different enough to be interesting but too close to marry. I’d love to go there, although I have to say that I think the first ten seconds would be the most interesting.

    More to come. Got to walk the dog.

  8. RJ Baliza Says:

    tim,

    what the …wrong genre, i think. too much science! science is what happens when artists are given a double shot of prozac! (or viagra, for that matter). and i’ve never seen the word ‘parallax’ used outside of ‘sniper scope’.

    we’re way deep ‘into the woods’ now.

  9. Larissa Says:

    More blog posts like this one! I am in love with the stars…and I don’t mean the ones that originate in Hollywood. (c:

    Wonderful wonderings and interesting information. I haven’t thought about some of this stuff for a while so thanks for the reminder.

    Have you ever read: The Age of Wonder?

    You should.

  10. Timothy Hallinan Says:

    I’m back. The dog had a better time than I did. Maybe if I knew what satisfaction she derives from all that sniffing, it would be different.

    Dana, I agree completely. The meditation of enormous distance is very cleansing to the human spirit. And how cool are astronomical names: The Great Attractor, The Wall of Fire, The End of Greatness. Quasars, for heaven’s sake. Got to put happenings on Maple Drive or Winnetka Circle into some sort of proportion.

    John, I only wish I were smart enough to have a good conversation with a cosmologist. I heard Herman Wouk tell a story about how, when he was writing THE WINDS OF WAR, he needed to write about the atomic bomb and therefore thought maybe he ought to learn a little something about the atom. So he went to the top, which is to say Richard Feynman: got himself an appointment, went into the great man’s office, sat down, and started to explain his problem. And, as writers will do, he got kind of, ummm, caught up in talking about his book until Feynman raised a hand and said, “Mr. Wouk? Please don’t take this wrong, but as long as you’re talking, you’re not learning.” Later on, Feynman said, “Calculus is the language God thinks in.” Well, that’s beautiful and kind of staggering, and it makes me feel really, really, really stupid.

    Hello and welcome Patg! I also have many photos of galaxies and links to thousands of others. As you suggest, when we look across distance, we’re also looking back in time. The universe is about 13 billion years old (and looking pretty frisky) and galaxies — and, by extension, stars and planets — have been around for at least nine billion years. (The Earth is about five billion years old.) All human history is about 30,000 years, and that’s being charitable; the history of human intellectual activity is probably closer to fifteen thousand years. That’s about as long, on any reasonable time scale, as a single spark from a sparkler. The whole of human existence, even if it lasts another 50,000 years, is to the cosmos just a little pssst. It’s there, it blinks, it’s gone. Pssst. Over the past nine billion years there have probably been millions of psssts, just little sparks in the universe, igniting, flaring, and leaving a cinder behind. And in each of them contained languages, dreams, yearning, Shakespeare, flying machines, anesthetic, Rembrandt, the piano, a thousand guesses at God, millions of individuals who each believed him/herself to be the center of creation. Pssst.

  11. EverettK Says:

    You’re a deeper man than e’er I thought, Mr. Hallinan.

    🙂

    I think that the reason I so like the hi-res orbital image of Victoria Crater, aside from the fact that it’s beautiful in its own right, is that we have lots of pictures from Opportunity “on the ground,” so we get two points of view, once distant, one up close, and can easily move back and forth between them in our mind.

    The universe is full of beautiful structures, EVERYWHERE, if you look just right, from the microscopic to the macroscopic to the cosmoscopic.

  12. Timothy Hallinan Says:

    Hi, RJ, wrong genre perhaps, but no one can doubt that there’s mystery galore out there. The Great Attractor? What in the world could it be? And the fact that the universe is more light-years across than the number of years it’s existed — when nothing can travel faster than the speed of light. Hmmmmmmmm.

    Riss, Don’t know about The Age of Wonder? What is it? (I think we live in one, though — actually, I think all ages have been ages of wonder to people who kept their eyes open.) Didn’t know you were a star-chaser, too, in the cosmic sense, I mean.

    Everett, I am not so wide as a door nor so deep as a well, but ’twill do. Because it has to. And, yes, you’re right about the beauty of natural structures. Literally the only thing that keeps me from the blankest atheism is the fact that nature defaults to beauty,

  13. EverettK Says:

    “…nature defaults to beauty.”

    I like that. A nice turn of phrase.

  14. Larissa Says:

    The Age of Wonder is a book that I’m currently reading. It’s premise originally struck me a potentially hokey but it’s actually really, really good. And you feel like you ‘re sitting down to have a cup of coffee with the author instead of reading. It’s about the “Romantic” age of Science and it talks about people like William Herschel and Joseph Bank and one or two others that I haven’t gotten to yet. To explain it sort of takes away what makes it good so if you get a spare moment, it’s worth the read. Definitely good.

    There’s another book that I have been trying to get through for just about ever now called The Fabric of the Universe by Brian Greene.

    Very good. Very dense. Age of Wonder is just as full of information but of a different sort.

    And yeah, I’ve had a thing for the cosmos ever since I was a kid. There’s a local around here who brings out this GIANT telescope that he built himself to show people Saturn. (c: Neat stuff.

  15. Howard Marder Says:

    Living in a city that pollutes the sky with light (New York) stargazing is almost out of the question.

    Thinking about the Universe is not limited to looking up as you are ably demonstrating.

    If you have an iPhone or iPad there is an incredible app called Star Walk that gives you the sky above and around you in the palm of your hand. It amazingly cuts through the clouds, the trees, the birds and airplanes flying overhead, the pollution and everything else and lets those of us who don’t live in a light-free location see what is above us.

    An added bonus is that you can see what is up there in daytime as well.

    You can get it through the iTunes or iApps store or whatever the silly name is for (U.S.) $4.99.

    All discussions on the Universal subject aside, this will open your mind even further. Just my opinion.

    Now, if you’ll excuse me I think that I’m going to see what’s up there at this time of the morning.

  16. Timothy Hallinan Says:

    Hi, Howard, and thanks for dropping by again. You’ve just given me my first good reason to get an iPhone. How cool is that, to be able to see stars in the daytime without the inconvenience of falling down a well?

    I wonder whether that’s true, by the way — that daytime stars can be seen from the bottom of a well. Seems like the sky’s scattered sunlight would still be essentially opaque.

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