Telescopes are designed to bring impossibly far away things closer to us, so why do we send some of them so far away? It's a big risk putting a telescope out into space, as opposed to keeping it safe and sound in an observatory on the ground, because it costs a lot of money to launch and maintain, and you kind of just have to hope that it doesn't get pummelled by random space junk. But there's a reason scientists go to all that trouble, says the latest episode of MinutePhysics: that perpetual troublemaker, Earth's atmosphere.
On the most basic level, the atmosphere gets in the way of a good telescope image because of all the unavoidable clouds, smoke, haze, and occasional rain. Even without all of that interference, a clear sky blocks a huge range of the wavelengths of light, so we only get to see visible light, and just a little infrared and radio waves. But there's so much more to see.
During the day, the Sun bathes us in an incredible amount of visible light, and this bounces off the air molecules and other particles in the atmosphere and completely overwhelms the light emitted from other stars you might be interested in seeing. And we're not even free from that at night, because that's when the light from the Moon and the artificial lights that brighten up our cities start to get in the way.
Even something as innocuous as the turbulence of air is enough to seriously distort the light given off by stars, says Henry in the video above, which is why they appear to twinkle in the night sky.
So what do we get when we pack up our telescopes and fling them out into space, far beyond the nuisance that is our atmosphere? Something so spectacular, you'll find it hard to believe it's real. I'll let Henry show you in the latest episode of MinutePhysics, and when you see it, be sure to give a whole lot of mental high fives to the men and women who managed to get those space telescopes out there in the first place. It was worth it.