When the earliest astronomers and philosophers looked up at the night sky, they never could have imagined a sight like this.
What if I told you there are only four single stars in this image?
That’s right. Four.
The rest are whole galaxies, full of billions of stars.
You can tell the foreground stars from the galaxies by the diffraction spikes–astronomer speak for those four bright spikes of light. Can you find them?
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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?
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Science at Your Doorstep 