Monday, 24 April 2017

T is for Telescope

The Universe is full of light. Therefore, if we want to know more about the Universe, we need to sample some of that light for analysis. One of the best ways to capture that light is in a lightbucket called a telescope.

For thousands of years astronomers only had one method of capturing light--MK-1 Eyeball, aka the naked eye. Look up in the sky, what do you see?

Lots of stars, most of the major planets and a few other fuzzy objects were easily observable with the naked eye. It had its limitations, as it only detected wavelength between 390 to 700 nm. Also, it was limited in its resolution and the number of photons it could capture.

For a few thousand years humans knew that carving glass into certain shapes could bend light, focusing it, bringing more photons to the human eyeball. Then really recently, in the early 1600's, a few bright sparks put a couple of lenses in a tube, looked through and yelped, "Wow! I can see far! Tele-scope!" The first refracting telescope was born. Thomas Harriot thought it would be nifty to look at the sky through this thing. He was right. To him, the Moon looked awesome. He could see such detail!

Galileo and his refractor.
About the same time, Galileo built his own and looked upwards. To his amazement, he found four moons orbiting Jupiter. These details were not visible previously. The ability of the telescope to capture more photos and resolve very distant objects was totally amazing.

Newton's reflecting telescope.
Humans are lots of fun because they'll take an idea and run with it, seeing if they can improve on the original design. Another bright spark (some guy named Newton) wondered if a parabolic mirror could serve just as well for focusing the light. Sure enough, it worked wonders.

So lots of gentleman scientists played with this new tele-scope technology, improving it in size and quality, and peered into the heavens with it. At first, it was mostly planets they stared at, and various nebulae, as the stars were too far away to resolve to anything but points of light.

That didn't stop them from having fun with the light they captured. Prisms were notorious for breaking plain light up into pretty rainbows called spectra (singular: spectrum). When that happened, they then discovered things like absorption lines, infrared,  and ultraviolet.

You can go really big with radio telescopes,
like they did in Arecibo.
The infrared and ultraviolet discoveries really sparked some imagination. Could there really be "invisible" light beyond the visible spectrum? If so, could we capture it?


With lower frequencies such as radio waves, they discovered they could be captured with antennas. Later, radio dishes (very similar in shape to the parabolic mirrors used to capture light) helped focus radio waves onto the receiving antenna, instead of just trying to pick up any old radio wave that happened to bounce by, like the aerials on our rooftops.

X-ray telescopes, same thing. A large parabolic mirror focuses X-ray wavelengths onto an X-ray detector. Problem with X-ray telescopes is that they're rather useless on Earth, as our atmosphere blocks out most stellar X-rays. So if we wanna gather X-rays, we've got to put our light buckets into orbit.
X-ray telescopes, like the Athena X-ray Observatory, can have lots of fun capturing the emissions of X-ray sources from orbit.

By the end of the 20th Century, humankind had come up with all kinds of telescopes to observe different kinds of electromagnetism. We're very good at capturing photons of all wavelengths, studying them, and thus, through sheer observation alone, we know about our Universe.

Do you have a telescope? If not, have you had a chance to look through one? If you haven't, see if you can find a local star party. Many planetariums and astronomical clubs hold them regularly. I recommend waiting a few months for Saturn to rise, for that is one spectacular planet to look at through a telescope.

Her Grace observes through a Celestron Nexstar 130SLT 5" reflector.


Sue Bursztynski said...

Nope. A friend sold me hers, but I never learned even how to set it up, let alone use it. Now I can't recall where I put it. Pity. They're such fascinating things, aren't they?

Well, pulsars were discovered through a radio telescope, eh? By a woman. Nice!

Keith Channing said...

Do I have a telescope? Yes, I have two inexpensive ones.
Can I work out how to set them up with this ruddy altazimuth mount? No, I cannot! Keith Channing, blogging at Keith Kreates

Linda Gardiner said...

Oh my gosh, a Light Bucket...what a great term. I do not have a telescope, just binoculars, but whenever I run across one I have to look through it.
Thanks for a great topic.

Texture My theme. "How to Build an Artful Life"

Bob Scotney said...

I studied astronomy as a general subject during my degree course at the University of St Andrews so had several opportunities to use a telescope. Years latter in the Canary Islands I would have loved one to look at the clear sky and the myriad of stars visible to the naked eye.

T for Tolethorpe Hall and different types of star in Shakespeare

John Davis Frain said...

I wish I had studied more astronomy. Especially when someone like you brings it to life. And shame on me for not knowing you were doing A to Z! I'm on vacation now, but wasn't in the beginning of the month, and I should have known.

Keep writing!