The Hubble Space Telescope

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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? Continue reading

Radio Astronomy: Limitations

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Astronomy is a labor of love, and radio astronomy is no different.

As I covered in my last post, radio astronomy deals with the longest wavelengths of the electromagnetic spectrum (a spectrum that includes visible light). Radio waves are not sound waves. They’re radiation just like visible light, infrared, and ultraviolet.

I’ll prove to you that radio waves can’t be sound waves. We get them from space—that’s why there’s such a thing as radio astronomy. But there’s no sound in space. Why? Sound requires something to pass through, and space is a vacuum.

So, we’ve established that radio waves are just another form of electromagnetic radiation. And astronomers love to collect any form of electromagnetic radiation. We can’t touch the stars ourselves, so it’s our only chance at learning about the cosmos.

Why? Because just about everything in the sky emits electromagnetic radiation.

Everything except black holes and a couple other things…but those are topics for another day.

But electromagnetic radiation isn’t easy to collect. And radio waves are especially hard. Continue reading

Interferometry

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Imagine you have an image like this. This object is faint and faraway, so you can’t make out much more detail. You know that other stars like it—closer, brighter stars—have looked like this and turned out to be two stars, nestled very close together.

How do you figure out what you’re looking at? How do you increase the resolving power on your telescope so that you can make out more detail?

A telescope’s resolving power is limited by its size. Bigger telescopes can make out more detail on faraway objects—that’s because they can gather more light. But now, we can make telescopes that are so big their size doesn’t limit their resolving power anymore.

The atmosphere does.

We obviously can’t change the atmosphere. So how do we get around this particular predicament? Continue reading

Improved Telescope Mirrors

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When it comes to telescopes, bigger is always better.

Bigger means more light-gathering power and better resolution. And a longer telescope—meaning, a longer focal length—can actually do wonders for your magnification power.

Light-gathering power, by the way, just means how much light a telescope can gather—and it works the same way as rain in a bucket. The bigger the bucket, the more rain you can collect.

And resolution means how much detail you can see in an image. It goes hand in hand with light-gathering power—more light means more detail.

So bigger, for serious astronomers, is the way to go. Until your mirror starts sagging.

Yeah…that’s a bit of a problem. But nowadays, we can fix it. Continue reading

Telescope Powers

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Have you seen one of these guys before?

You probably have, even if you don’t recognize this brand-new innovation. This is the European Extremely Large Telescope, or the E-ELT. I know, imaginative name, huh? Anyway, it’s not all that different from one of those white observatory domes you’re used to seeing.

Astronomers keep building new observatories. They keep putting new telescopes into space—Hubble, Spitzer, and James Webb, to name a few. But the common goal of all the telescopes they build is to make telescopes that are as big as possibly possible.

Why? I mean, are astronomers just huge braggarts that like to impress us all with their big toys?

Well…I’ll admit that we astronomers have a lot of fun with our toys. But we need huge telescopes for a much better reason than bragging. Continue reading