How to look through a telescope

Last night I went to a lecture at HWS by Robert Bowman, a former Air Force colonel who was in charge of the “Star Wars” program under Reagan in the 1980s. He spoke about his road from warrior to peacenik. Very interesting talk. Anyway, I thought there might be a good crowd, and I figured that a little stargazing might go well with an exercise in imagining a very different world, so I packed up my small refractor telescope and mount into the car. I left during the start of Q&A, and Larry Campbell, who was hosting the speaker, announced that I’d be outside at the end of the talk.

I set the scope out under the glaring lights in front of the library. Before I tell the rest of my story, let’s talk about light pollution. As an astronomer, I hate light pollution, which is basically defined as light pointing wastefully into the sky instead of on the ground where we’d like it to be. There’s a growing world-wide movement against light pollution. It makes the sky ugly and orange. It hurts animals and trees. It hurts people. And keeps us ignorant of the existence of the rest of the universe, a necessary context without which we cannot make wise decisions for the future of a fragile, isolated planet. Light pollution is also bad for our immediate health and safety. The American Medical Association has just declared that glare from outside lighting is a public health hazard. Read why here.

Anyway, the lights around the library were glaringly bright. I could however see the two targets for the evening’s program–the almost full Moon and Jupiter. I started with Jupiter. I was interested to see how students would react. There’s a whole batch of new first years that just arrived on campus…would they be too cool for school? How would the experience compare to setting up the scope on the sidewalk downtown? I have to admit I assumed there would be a slightly more educated audience.

They weren’t too cool. Well, some boys in cars that zoomed by did shout a few things at us. But with the doppler shift, I couldn’t really tell what they said. I assumed it was complimentary. A guy with a telescope is really cool. And anyway, there was a respectable crowd around me, and they were just wishing there was someone in their car to impress. The stargazers that joined me were enthusiastic, some of them contagiously so. For some of the first years, I can see them thinking at the back of their minds: yeah, this is college!

But in terms of knowledge of the universe, they were like most people I meet. Which is to say, pretty unaware of what’s out there. It’s not a dig. It’s not their fault. There just isn’t enough amateur astronomers and earth science teachers with the desire to teach about the greater context of earth to go around. And I think there’s a resistance in humans to this. Some people don’t want to feel tiny and insignificant, and advertising agencies rush in to convince us it isn’t so (and feel better by buying our new hyperdoodadthingy!) Bill McKibben once watched all the programming available on every cable channel for a 24 hour period–it took him weeks. And what he found was a resounding and overwhelming message; the individual is the most important thing. Not family. Not community. Not world. He wrote a great book about the experience, called The Age of Missing Information:

We believe that we live in the “age of information,” that there has been an information “explosion,” an information “revolution.” While in a certain narrow sense this is the case, in many important ways just the opposite is true. We also live at a moment of deep ignorance, when vital knowledge that humans have always possessed about who we are and where we live seems beyond our reach. An Unenlightenment. An age of missing information.

-Bill McKibben

But there’s a countervailing force, a desire or curiosity to see what’s out there. It drives people to the telescope. As if the thing itself excuses the basic curiosity, breaks the monotony of day to day living. There was some people at the telescope last night that were very excited to see Jupiter. Joe, for example, who was from New York City. He mentioned that looking at the night sky through a telescope had been a life-long dream. I was pleased to be able to oblige. (But Joe, please, don’t yet consider the dream fulfilled. There’s a whole sky up there that you could barely see because the colleges like to light up buildings and trees as if there was no such thing as night. Go out on one of the side roads around the college at night with a few buddies and look up. You’ll be started by what you can see.

Yang Hu and Joe at the telescope.

Yang Hu and Joe at the telescope.

Jupiter is 11 times the diameter of earth. Cut Jupiter in half and scoop it out like a cantaloup and you can fit all the other planets inside it. It’s makes the solar-system a rather portable kit, just find another star. Jupiter is 500 million miles away. Get in your car and start driving, you’ll get there in about 900 years. Beware: cops love to use the asteroid belt between the orbit of Mars and Jupiter as a speed trap. Jupiter is a gas giant like Saturn, but bigger and different. It’s surface is characterized by beautiful belts and eddies of gas. Through the 3-inch refractor I had set up, you could clearly see the two darkest cloud bands across the planet.

Jupiter has four large moons, called collectively “The Galilean Moons”. They are: Io, Europa, Ganymede and Callisto. We named them after Galileo because he was the first human to see them, through an early telescope. He didn’t call them “Galilean Moons”–he called them “Medicean Stars” because 1) he didn’t know they were moons (they look like stars through small telescopes) and 2) because the de Medici family was sponsoring his research. You have to nod to your sponsors. Anyway, these four moons are really important to the development of human thought about the cosmos, because they helped Galileo realize that the earth might not be the center of the universe. The idea was that everything revolved around the earth. But night after night, Galileo watched these four “stars” dance around Jupiter. Even in one observing session, they can shift position. Basically, he concluded that if something could orbit Jupiter, then everything didn’t orbit the earth. Thus, a revolution in scientific thought and a very unpleasant run-in with the Roman Catholic Church that didn’t get resolved until 1992 when John Paul II stated that it was all a case of “tragic mutual incomprehension.” I’ll let that hang for a moment.

Cool College Kidz Hang Around My Telescope

Cool College Kidz Hang Around My Telescope

The dance of the Galilean Moons was charming last night. At first only two were visible. I thought it was Calliso and Europa. Io, I knew, wasn’t visible through my scope because it was over Jupiter’s surface so it blended in. I also thought that Ganymede was transiting Jupiter, but I was wrong. Later, someone said “I see two stars above Jupiter and one below.”

“Two above?” I checked. He was right. Europa and Ganymede were so close they had appeared as one. Not an hour later, they were visibly separate. It’s amazing how quickly things can change in the cosmos. Just when I absorbed that, something else: Io’s shadow appeared on Jupiter’s surface. And unlike Io, which is about the same shade and color of Jupiter and so blends in as it transits, Io’s shadow appears as a sharp pin-prick of black. Most people could see it.

I stated a while back that my mission is to bring views of the universe to them who need seeing it. I have to remember that that means pretty much everybody, from working class blokes on the sidewalk downtown to fairly privileged college students.

Bonus Coda: I’ll close with a little piece of advice I gave to most of the people who stopped by to look through the scope. Most people close one eye shut tight when trying to look through the telescope. That works, but it’s not very comfortable and quickly becomes untenable. Instead of doing that, leave both eyes open, but cover the one that’s not at the eyepiece with your hand. It’s way more relaxing that way. Here, a student demonstrates the proper procedure:


Bonus Coda II: Yang Hu took a photo of the moon through the telescope with her digital camera. Check it out:

The mostly full moon. The top edge is eclipsed by the eyepiece lens.

The mostly full moon. The top edge is eclipsed by the eyepiece lens.

Bonus Coda III: “Human beings–any one of us, and our species as a whole–are not all-important, not at the center of the world. That is the one essential piece of information, the one great secret, offered by any encounter with the woods or the mountains or the ocean or any wilderness or chunk of nature or patch of night sky.” -Bill McKibben, The Age of Missing Information


9 thoughts on “How to look through a telescope

  1. Thank you so much for sharing, i get my first telescope tomorrow and i am so excited …cant wait till mid oct. to see those two (moon and jupitar) back together….;-)
    greetings from the other side of the world under the same starts!

  2. Thank you so much for sharing, i get my first telescope tomorrow and i am so excited …cant wait till mid oct. to see those two (moon and jupitar) back together….;-)
    greetings from the other side of the world under the same stars!

    • Manuela,
      If you have trouble with the new telescope, finding things or operating it, please feel free to write me. I’d be happy to help you out. Cheers

      • I brought my first telescope and the telescope aims at the the moon comes but goes away in a second

      • Tareq,
        The first question is, can you see the entire moon through the eyepiece? If not, then you are using a too powerful eyepiece to begin with. Eyepieces come in different focal lengths (for example, 24mm and 12mm) and the shorter the focal length, the higher the magnification. If you only see a part of the moon, then it’s possible that what you are seeing is the earth’s rotation pulling you and your scope away from the moon! The moon appears to rise and set just like the stars and the sun, and a telescope pointed at the moon will show the moon’s apparent movement unless it has a motor to compensate for the earth’s rotation. With a low power eyepiece, however, the moon should stay in the scope long enough to get a pretty good look it, and you should be able to easily push the scope so it’s back in the field of view. If you are using a low-power eyepiece, and you can see the whole moon, but it slips quickly out of view, then it sounds like a problem with the telescope mounting. The scope might not be tight enough in the mount, so it’s not staying where you pointed it when you let go of it. Without knowing what type of scope it is I can’t say for sure. Can you tell us what you bought?
        Don’t give up, there are answers!

    • Manuela,
      Actually, if you don’t have problems with your new scope, I’d love to hear about your first experience with the telescope too. That’s very exciting! Expect rain and clouds for the next three days, it’s the telescope buyer’s curse.

  3. Hi, I bought my first telescope and on my first day, out of pure luck, I managed to see Saturn and I got so excited I almost woke up the whole neighborhood so they could watch it. Then on the next days I had no luck at all and couldn’t see a thing; just before I was going to bury the thing on my garage I tried to fix the red dot finder that came with it and then I could point at anything with it and now we are back in business!!!
    By the way, Saturn appears westbound around 8:30 PM but when I try to see it at 300x it looks super blurry, is there a way I could fix that? I tried adjusting the focus but no luck so far.

  4. Andres,
    The first question is…what kind of telescope did you buy? How big is the primary mirror or objective lens on the front?

    300x is a lot of power and it would take a pretty big telescope (in terms of the diameter of the objective I mentioned above) to be able to show a sharp image at that magnification. And it would take a night of what we call very good seeing, which means the atmosphere has very few thermal disturbances. Those nights are pretty rare! But you should still get a sharp view of Saturn at lower magnifications. Like getting really close to a magazine photograph, the image starts to break down into little dots and you can’t tell what it is anymore. Move to normal reading distance and the image appears sharp. Make sense?

    Amateur astronomers have a rule of thumb for figuring out the maximum useful magnification of any telescope. Basically we say 50x per inch if aperture. If your scope has an objective of 76mm or 3 inches, the maximum useful aperture is 150x. This is a very general rule of thumb, and assumes really great optics and perfect seeing. So in practice, it’s lower.

    Those starter telescopes that advertise 500x! are often not bad telescopes, but can’t possibly present a decent image at that magnification.

    I hope this “clears it up” for you. So keep the magnification down and look for details on Saturn, the shadows of the rings, etc. And train that telescope on the moon for a spectacular view of our nearest neighboring planet!

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