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One of my favorite objects to show people at astronomy outreach events is the Orion Nebula. Not only does it reside within a fairly well-known constellation, but it’s a gorgeous sight to see with a good telescope.
There’s no time like the present up here in the northern hemisphere. Orion is a winter constellation and rises high in the sky this time of year. Not to mention, as a stellar nursery, talking about the Orion Nebula follows on perfectly from my last couple posts on star formation.
If you’ve ever seen the Orion Nebula through a small telescope, you’re probably wondering what all the rage is about. It mostly just looks like a bluish haze around a star—like the telescope operator didn’t tune the focus quite right.
But if that’s all you’ve seen, I promise you, you’re missing out…
If you’re from a larger city and haven’t had the opportunity to venture into a place like the desert, you might not know what you’re looking at. That’s the Milky Way, our name for our galaxy.
Inside this galaxy are billions of stars, including our own. Galileo Galilei was the first to discover that it was really many tiny points of light, not just a cloud-like haze across the dark night sky.
We can’t see our galaxy from outside, but we can learn a lot about it by looking out at it from within. It’s difficult. It’s like trying to learn about a building if you can never step outside one of its rooms.
But we can do it, with the help of the spectrograph.
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.
Right next to light, the telescope is an astronomer’s most valuable tool. There are so many different varieties of telescopes, it can be hard to keep them all straight. But they can all be sorted into a few basic types, and that makes choosing one a lot simpler.
Two very common types are reflectors and refractors, and each one in the image above is one of these. You can tell a reflector by its cylindrical design. They all look like cylinders, you say? Well…refractors are a little bit different.
Take the two telescopes on either end of this lineup, for instance. These two—the far left and the far right—are refractors. And you may notice that, unlike most of the rest, they’re not perfect cylinders.
Look closely. You’ll see that, not only is the end pointing up a bit wider than the rest of the telescope, but there’s a little tiny piece tacked onto the end. That same little tiny piece is tacked onto the side for the reflectors.
Every reflector and every refractor can be recognized by these basic qualities. But what they do with light is more important.
People think of rainbows as a symbol of happiness and fortune. There are even myths that leprechauns hide gold at the end of a rainbow. That’s more of a tease than good fortune, if you ask me, because it’s impossible to reach the end of a rainbow.
That’s right. Impossible.
Some people wonder if rainbows look the same from the back. The answer’s no. They don’t. You wouldn’t see a rainbow if you were standing behind it.