Light! An Astronomer’s Best Friend
From backyard stargazers to the greatest astronomers, no matter what level, the more light we can gather from the heavens, the better.
Until we find a way to travel past the speed of light, which the great Albert Einstein pretty much declared impossible, people from Earth won’t be able to travel to the stars anytime soon, if ever.
Einstein said that as you get closer to traveling at the speed of light, your mass increases infinitely, which requires infinite amounts of energy.
People may journey to Mars someday at great expense, and maybe some of the other planets in our solar system. Beyond that it may not be impossible.
You have to leave the door open a crack though. As little as a hundred years ago, the same was said about going to the moon.
So how do astronomers know what they do about the stars, and how do we expect to learn more? The answer is light. The greater the amount of light your telescope gathers, the better you’ll see the universe.
When it comes to any telescope, it’s not how much you can magnify whatever you’re viewing. It’s about how much light you can gather in your scope.
Even though the human eye is a wonderfully efficient light-gathering tool, it can’t match the light-gathering ability of telescopes.
No matter what kind of telescope you have, either a refractor, reflector, or a Schmidt-Cassegrain, the wider that scope, the more light it can capture and the clearer the image will be.
Professional astronomers, and even some amateurs, don’t just settle for looking visually through the telescope. They take images through telescopes to gather light for a longer time to see even more detail.
The best thing that’s happened to astrophotography in the last 50 years was the development of CCDs (charged-coupled devices) that can electronically detect and accumulate much more light and do it much more efficiently than even the human eye.
Amateur astronomers, like yours truly, love to take beautiful celestial images with CCDs or other digital astronomical cameras hooked up to telescopes. It takes a sizable investment in money and time, but I find it’s so worth it.
The pros gather tremendous amounts of light with giant telescopes on high hills and mountaintops where skies are darker and the air is thinner. That allows even more light to enter the scopes and imagers. One of the best observatories globally is the Keck Observatory on Mauna Kea Mountain in Hawaii.
One of the latest techniques developed is to gather even more light by electronically combining the light gathering ability of multiple telescopes to acquire an even clearer image. This is called interferometry and shows a lot of promise for the future.
And then there are telescopes based in space, like the Hubble and the new James Webb telescope.
The Hubble and James Webb are not as big as some ground-based telescopes, but without Earth’s atmosphere in the way, the images it produces are beyond amazing. Not only do they gather visible but also infrared light.
What is truly amazing is that this image contains so many galaxies that only cover a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground!
Visible light not only provides clarity to all astronomical images, but it can also be broken down into separate components or wavelengths. It’s called a spectrum and acts as a fingerprint of what elements are present in and around a star, nebula, galaxy or whatever.
You can easily get a crude spectrum of sunlight with a prism or a light spray coming out of a garden hose. This is the same principle that produces rainbows.
Not only can astronomers deduce what elements are out in the universe, but stellar spectrums can also directly or indirectly reveal the temperature, distance and many other characteristics of stars. Light and radiation packed in starlight can reveal so much information if you know how to dig for it!
Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of "Stars: a Month by Month Tour of the Constellations," published by Adventure Publications and available at bookstores and adventurepublications.net. Contact him at mikewlynch@comcast.net.
