Here's an exercise in perspective. Sit still on a clear night when the moon is not full and look up.
At first, you see the things you always see -- the Big Dipper, the Little Dipper, Orion. Then, you notice the strip of stars spilling across the sky, and you know that's the Milky Way. But on this night, you will look farther than you have before.
On Wednesday night, Colorado Mountain College astronomy professor Jimmy Westlake will deliver a lecture as part of the Alpine Enrichment Program titled "Galaxies."
The Andromeda Galaxy, known to astronomers as M31, is the closest galaxy to our own, the Milky Way. It is a little larger than our galaxy and appears in the night sky as a "fuzzy smudge," Westlake said. The Andromeda Galaxy is the most distant object we can see without a telescope.
The light we are seeing was emitted from the galaxy two million years ago.
The Andromeda Galaxy is important historically, Westlake said, because before the 1920s, astronomers thought the Milky Way was the only galaxy in the universe.
"They called it 'The Galaxy'," he said. "They had seen these fuzzy things like M31, but they thought they were gas clouds in our galaxy."
The American astronomer Edwin Hubble was the first scientist to observe that the M31 actually was made up of individual stars.
Later, his namesake Hubble telescope would prove that there were billions of other galaxies in the universe.
"On it's largest scale, the universe is made of galaxies. They are the building blocks of the universe," Westlake said.
The number of galaxies in the universe is uncountable but is estimated in the hundreds of billions. "Astronomers had Hubble look at the blankest piece of space for 10 days," Westlake said. "In a piece of space smaller than looking through a soda straw, Hubble saw 10,000 galaxies -- galaxies we didn't know were there."
But our current map of the observable universe is limited by the age of the universe.
"We believe that the Big Bang occurred 13.7 billion years ago," Westlake said. "The universe isn't old enough for light farther away than 13.7 light years to have gotten here."
The farthest object in the known universe is 12 billion light years away, Westlake said. "Those are the faintest things observed with the Hubble telescope."
During Westlake's slide lecture, he will show images of distant and ancient galaxies taken by the Hubble telescope.
"When we look at these images, we are actually looking back in time 12 billion year ago, very shortly after we think the universe was formed," Westlake said. "The light we are seeing was emitted when the universe was very young, and those galaxies were in their formative stages." By observing what they now can see, scientists can begin to understand how galaxies form by watching them as they formed.
"Those galaxies could be totally different today than how we see them today," Westlake said, "but we won't know that for another 12 billion years."
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