June 21, 2009Website of the Week
Here in New York City, when we look up even on a clear night we see a handful of stars at best, scattered across the sky glowing damply like cigarette butts on the sidewalk outside a bar. If we want to contemplate the heavens, we stay inside and look in books or on tv or in the computer.
The universe is currently estimated to be roughly 14 billion years old. That means the farthest objects from which our instruments can see light are less than 14 billion light-years away. But the universe has been expanding the whole time — billions of galaxies (we've read estimates from 125 to 500 billion of them), each made up of billions of suns, expanding outward in an immense sphere now thought to be about 150 billion light-years in diameter.
This is all relatively new knowledge; the existence of other galaxies besides the Milky Way wasn't even known for certain until the 1920s. Less than a century ago! Astronomers have been scrambling to photograph, map and catalogue visible galaxies ever since.
For the last few months, we've been helping. The Galaxy Zoo project was begun by some clever astronomers in 2007. They had photoed about a million galaxies through the Sloan Digital Sky Survey telescope in New Mexico, and realized it would take an army of undergraduates years to do even the basic sorting. So they opened that process up to the public and asked for volunteers. More than 150,000 people around the world have signed up. We view SDSS photos of one galaxy at a time, and catalogue it by shape and other visible characteristics. It's fascinating. The photos are often breathtaking. That's one of the beauties we've catalogued in the photo above. We've seen dozens of beauties. Galaxies like vast blue pinwheels in space, or like spherical clouds of stars. Galaxies colliding, or shredded and pulled out of shape by collisions long past. Galaxies that are whirling eddies of suns, or donut-shaped, or S-shaped. Galaxies being born, and galaxies dying. Galaxy Zoo lets you compile a gallery of your personal favorites.
After a while, you begin to appreciate that vast as the universe may be, it's full to bursting with stars. You rarely see a photo of a galaxy seeming to float alone in the void. More often, the one you're focusing on stands in a whole field or family of galaxies, and you realize you're looking at hundreds of billions of stars in a single photograph.
The genius of Galaxy Zoo is that you're not just star-gazing, pleasant as that is. You feel like you're contributing, in a small and rudimentary way. Mapping the universe in your spare time. As Internet pastimes go, it's awfully satisfying.
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Comments (3)
Peculiar Galaxies
Classifying gigantic, gorgeous objects. Talk about beguiling time! The history of galaxy classification contains a very telling parallel to another topic on this site. Halton Arp was a highly regarded American astronomer who compiled the "Atlas of Peculiar Galaxies." When the data that he collected led him to reexamine the central dogma of modern astronomy, he was vilified, refused publication, denied time on the big telescopes, and driven to find work in Europe. Peter Duesberg is the Halton Arp of virology. Celia Farber is the Halton Arp of journalism.
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June 21, 2009
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The math in your estimated age of the universe does not add up. If the universe is only 14 billion years old, that makes it approximately 28 billion light years across. If it really were 150 billion light years across, it would have to be 75 billion years old. There are no theories where light can travel >C except during hyper-inflation. If there is any theory that contradicts my thinking, I would love to read about it.
However, at the same time, the Universe must be significantly greater than 14 billion light Years old, OR, we are very near the center of the thing. Common sense says that is unlikely either, so its more likely the Universe is somewhat older than physics suggests, as it seems too much a coincidence for use to be smack dab in the center! We see the same age in all directions, if we were a billion light years off center, we would be able to measure it.
However, at the same time, the Universe must be significantly greater than 14 billion light Years old, OR, we are very near the center of the thing. Common sense says that is unlikely either, so its more likely the Universe is somewhat older than physics suggests, as it seems too much a coincidence for use to be smack dab in the center! We see the same age in all directions, if we were a billion light years off center, we would be able to measure it.
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July 08, 2009
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Thanks, Mark. We're just going with what the astronomers say: that the universe began a little under 14 billion years ago, has been expanding ever since, and is currently estimated to be as much as 150 billion light-years across... Then again, astronomers used to say there was nothing beyond the Milky Way, so if they're wrong now we won't be flabbergasted.
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July 08, 2009
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