Illustrations by John Garrett, my co-presenter for the Orange County Astronomers’ What’s Up show tonight. More precise labelling and captions to come later.
galaxies
The Hubble Space Telescope
The Hubble Space Telescope is one of the most famous telescopes in the world.
Oops, excuse me—one of the most famous telescopes built.
Hubble, after all, is certainly not in this world. Unless you call the universe the “world,” it’s about as far from being in this world as you can get. It’s in space.
Hubble isn’t that different from an ordinary, ground telescope. It’s only as big as a bus. There are bigger optical telescopes. Its mirror is 2.4 m across—hardly an achievement by modern-day standards.
Palomar Observatory, which was the biggest telescope in the world when it was built, has better optics than Hubble, meaning its images are a bit crisper.
But that doesn’t keep astronomers from continuing to use Hubble. In fact, if you want to use Hubble, you have to get in line—it hardly has time to complete all the projects astronomers ask of it, even observing the night sky 24/7.
So why is Hubble so useful? Continue reading
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Where Are We?
In the 4th century B. C. E. (Before Common Era), scientists believed the Earth was the center of the universe. Before that, they were convinced the Earth was flat.
Now, most of us know that the Earth is not the center of the universe—nor is it flat. (Although there are definitely those who still believe we live atop a flat disk world, hurtling upwards through space.)
Not only is the Earth not the center of the universe, neither is the sun—and it’s not even the exact center of our solar system (you can read more on that here).
And if we zoomed out much farther and took a look at our galaxy from above—or below, take your pick—we’d find that the sun is not even near the center of its own galaxy.
It is, in fact, located in a small “spur” of stars just off one of the spiraling arms of the galaxy. And if our universe is in fact infinite—as the prevailing theory describes—then there can’t even be a center, so our galaxy is not the center of anything.
But what does all of this mean? Where exactly are we in the universe?
Continue reading
Science at Your Doorstep 