Archive for the ‘Sidewalk astronomy’ Category


Observing report: the transit of Mercury from western Colorado

May 19, 2016

Mercury transit 9 May 2016 - telescope setup

I was in Utah from May 4 to May 15, chasing dinosaurs with Mike Taylor, a colleague of mine from England. I took a telescope along in hopes of getting some dark-sky time, and to hopefully catch the transit of Mercury on May 9.

Things did not look promising at dawn on the 9th. I was in Fruita, Colorado, and when I got out of bed, the sky was completely overcast. Mike and I decided to head out west of town to visit Rabbit Valley, where a nearly complete skeleton of the long-necked dinosaur Camarasaurus is visible in a hard sandstone ledge. (Why is no-one excavating this dinosaur? Because we already have many nice specimens of Camarasaurus, and the sandstone around this one is like concrete. It would be a mountain of work for very little payoff.)

We spent about two hours measuring and photographing the skeleton, and as we did so, the clouds started to break up a bit. By the time we got back to Fruita, a little after 11:00 AM, the sky was clear except for a few scattered wisps of cloud. I set up my telescope in front of the Dinosaur Journey museum and started watching and photographing the transit.

Mercury transit 9 May 2016 - Mercury crossing the sun

I was using the same setup as in the last post: my Celestron C80ED refractor, a Celestron 8-24mm zoom eyepiece, and a GoSky full aperture solar film filter. For photography, I used a Nikon Coolpix 4500 for still photos and my iPhone 5c for video.

I caught about the last hour of the transit, and I got to share the view with about a dozen museum staff and passersby. A few light clouds drifted through the field of view, which looked pretty cool and didn’t obscure the view at all.

At 12:42 Mercury finished exiting the disk of the sun. The next Mercury transit will be in 2019 – I hope I’m as lucky then as I was this time.


Observing report: the transit of Venus in Claremont

July 4, 2012

Here, just one day shy of being one month overdue, is my post on the transit of Venus on June 5. As promised, I took scopes downtown and did some sidewalk astronomy, and eventually some rooftop astronomy. As with the solar eclipse on May 20, the primary instrument was my son’s Astroscan with a homemade sun funnel, and once again it performed beautifully.

My partner in this enterprise was fellow Claremont paleontologist Matt Benoit. He was there for the whole thing, and helped keep scopes on target and help people understand what they were seeing. We hit a grocery store beforehand for soda and snacks and basically made an extended party out of the event.

I wanted to see the transit, period, but I was especially keen to watch the entry of Venus onto the solar disk to see if I could spot the “black drop effect” that bedeviled transit-timers in previous centuries. Sure enough, as Venus started to pull away from the limb of the sun there was a persistent dark blob or zone that seemed to connect the planet to the black space beyond, like surface tension keeping a drop of water from falling off the faucet. The black drop effect was once thought to be an effect of the atmosphere of Venus, but it’s not, because airless Mercury shows the same effect during its transits (the next of which is coming up in 2016, by the way). It’s nothing to do with our visual perception, either, since it’s easily recorded photographically, as you can see above. It’s now understood to be an effect of diffraction when a vanishingly thin line of light separates two darker spaces or silhouettes. You can see it by holding your finger and thumb up to the light and bringing them together–just before they touch, the black drop effect will seem to bridge them.

Along with the Astroscan and sun funnel, we had along the Celestron Travel Scope 70 with the aperture mask and solar filter described in this post, for direct viewing. Here’s my friend Marcy, who was there with friends for about half of the transit, getting her first look.

Although we both put in time on both scopes, for the most part I drove the Astroscan while Matt minded the Travel Scope. He also helped people get some photos through the eyepiece, as he did here with Marcy’s DSLR.

The view through the filtered scope was not as detailed as in the sun funnel, but the warm yellow color was more aesthetically pleasing, and many of our visitors appreciated both views.

Like the eclipse, the whole effect of the transit was a little unreal. In addition to the scopes, we also had eclipse glasses and a piece of welder’s glass. Every few minutes we would look up with our naked eyes and see a little black dot on the sun, and know that it was a whole world. And not just a world, but a twin of Earth. Someone on Mars watching a transit of Earth would see something very similar–our whole planet, all our evolutionary and human history, everything we’ve done or built (except for the handful of tiny things we’ve sent away)–all shrunk to a point, no larger, to the naked eye, than the period at the end of this sentence.

We had a steady stream of visitors downtown until a little after 6:00, when the theater blocked the view of the sun from the public square. So we decamped to the top of the parking garage across the street. Some people followed us over from downtown, and some found us up there on their own. One guy said that he found us because he had Googled for Venus transit events in Claremont and found my morning-of invitation post, which is nice, because that’s exactly why I put it up. In all, about 85 people saw at least some part of the transit through one of our scopes.

My son, London, watching the very tail end of the transit with the welder’s glass.

Venus was still crossing the face of the sun when they set together. As with the eclipse, I managed to get a shot right when the world crossing the sun touched Earth’s horizon. A moment later, it was gone, and the last transit of Venus until 2117 was over. I’m glad I got to see it, and to share it. I hope you had the opportunity to do the same.


See the transit of Venus in Claremont

June 5, 2012

If no clouds come to spoil the fun, I will be in downtown Claremont this afternoon (Tuesday, June 5) with a scope set up for free public viewing of the transit of Venus. The transit starts at 3:06 PM, PDT, and will still be in progress when the sun sets at 7:59. I plan to be there for all of it. If all goes well, from about 2:50 onward I will be in the public square in front of the theater, on the northeast corner of First Street and Indian Hill Boulevard. Whenever the sun gets low enough to go behind the theater, I’ll head up to the top of the parking garage across the street, to watch the sun set with Venus still crossing the solar disk. You, whoever you are, are welcome to join me.

If by some freak chance it is cloudy this afternoon, I’m going to throw my gear in the car and run up to Big Bear, which gets more sunny days than almost anywhere else in SoCal (that’s why the solar observatory is there). In which case, you’re still welcome to join me, if you can find me. Try the Discovery Center on the north shore, if it’s sunny…or the nearest pub if it’s not.

Fingers firmly crossed for clear, sunny skies!


Sidewalk astronomy with SkyWatcher Mak 90

March 9, 2012

I took the little SkyWatcher Mak downtown tonight to do some sidewalk astronomy. I haven’t blogged about sidewalk astronomy in a long time because I haven’t done any in a long time. And that’s been bumming me out. I was away from it for too long.

I got started doing sidewalk astronomy back in 2009, as part of the global 100 Hours of Astronomy event during the International Year of Astronomy. It’s a pretty straightforward gig: take a telescope to a public space and give passersby free looks at stuff in the sky. The moon and planets are good targets, because people are familiar with them (not everyone knows what the Pleiades are), they’re naked-eye visible so you can point them out to folks, they punch through city light pollution just fine, and they look great in small telescopes. I know some sidewalk astronomers take big telescopes, and more power to ’em, but I have found that my inclination to go do it is proportional to the size of telescope I have to lug downtown (about five blocks from my house).

For the first long while, my sidewalk scope was my original 90mm Mak, the Orion Apex. It was perfect for the job: compact, lightweight, able to be set up and torn down in about one minute on either end, sharp optics, easy for newbies to focus… Then one night at an astronomy club outreach I reach out in the dark and turned the wrong knob on the mount, and dropped the telescope. On the way down it hit a tripod leg and my foot, but neither absorbed enough energy to keep it from hitting the ground pretty hard. The impact spalled a bit of coating (at least, and possibly some glass underneath it) off the primary mirror. I sold it cheap to a fellow amateur who thought it was salvageable.

My next sidewalk scope was another 90mm Mak, an old orange-tube Celestron C90. I had always wanted one, ever since I saw my  first telescope catalog back at age 12. They are sweet little scopes, build like tanks, and since they focus with a rotating barrel like a camera lens there is not much that can go wrong with them; if the focuser ever gums up you just unscrew the front part of the tube, re-lube the threads, and screw it back together.

It turned out, though, that I liked the idea of the C90 better than the actual thing (this was a far different beast from the modern C90 that is on sale at Amazon and elsewhere). The rotating barrel sounded good in theory, but in practice it was a huge pain to focus the scope while keeping it pointed at an object, especially at moderate to high powers, and especially for people with no experience. I used the C90 for sidewalk astro once or twice and then sold it.

(Aside: one of these days I’ll blog about the joys of buying and selling used telescopes. The bottom line is, scopes hold their value pretty well. If you are judicious and buy used you can usually sell them for what you paid for them, so once you’ve ponied up the initial investment you can essentially try out new [to you] gear for free.)

Then I went through a phase of doing sidewalk astro with bigger scopes: a 5″ f/7 reflector on a homemade mount, a 5″ f/5 reflector (Stubby Fats), and an 80mm f/11 refractor (Shorty Long). These are all fine scopes for showing people stuff in the sky, but not so hot for having to lug five blocks. I needed a dinky scope, something bigger than my 50mm refractor (which is too small for that kind of work) but smaller than my other scopes. Frankly, what I needed was a 90mm Mak, I’d just put myself in the position of not having one.

Until now. Suitably armed with the SkyWatcher Mak, I went forth into the warm spring night, and between 7:35 and 8:45 I showed 48 people the moons of Jupiter. The seeing was godawful, as bad as I have ever seen it. Jupiter was a visibly waving ball of fire, when normally I can see at least half a dozen cloud bands (as shown in the previous post). But the Galilean moons were all visible, strung out in a ragged line to the west of king of planets, and everyone who stopped to look seemed bowled over by the views, so who am I to complain?

I didn’t take the multi-mount that came with the scope, just the little Universal Astronomics DwarfStar alt-az mount that I used to use with the old 90mm Maks (shown in the picture at the top of this post). I left the finder and diagonal on the scope, put it nose down in the included backpack, put spare eyepieces in the side pockets, put all that on my back and carried the folded tripod and mount in one hand. It was great, just like old times.

John Dobson argues that the only measure of a telescope’s value that is worth a damn is the number of people who have looked through it. By that metric, I reckon this little Mak may end up becoming my most valuable scope. I’ll keep you posted!


Just another perfect evening

June 24, 2010

I prefer to do sidewalk astronomy when the moon is waxing, so it’s well up in the early evening, and not too close to full moon, so that there are still some nice shadows along the terminator. Last night was about the last “good” night for it, in my book, so I took my cheap scope downtown for an hour, and showed 53 people the moon and Saturn. Two of my visitors were a father and son who, it turns out, had stopped by the very first time I did sidewalk astronomy, back in March of 2009. In fact, they’d just been talking about that night as they were strolling down to the fountains, and hey, there I was again.

Good times.


Cheap scope put to good use

June 22, 2010

You’ll recall that Amazon recently had a nice intro-level reflector on closeout for a stupid-awesome price (sadly they’re out now no longer stupidly cheap, just sorta cheap), and that I got one, sold the included tripod, and got to work building a new mount for it. After about three weeks of non-action, I finished the mount today, and took the scope downtown this evening to do some sidewalk astronomy.

It was fun, and funny. To me, this 5″ scope is small. Like, that’s why I got it–because I wanted the biggest scope I could carry around with one hand. But out in the wild, where most people’s only exposure to telescopes is by way of shaky 60mm department store horrors, a solidly mounted five inch scope is but a little lower than the Hubble. People thought it was HUGE. They gravitated, especially kids. We were down at the fountains for an hour and 32 people came by for a look at the waxing gibbous moon. The last person was the 1027th passerby to look through one of my scopes since I started doing sidewalk astronomy in the spring of 2009.

The moon was pretty great, too. And obviously I’m pleased with the scope.

Single 1/60th of a second exposure with a handheld Nikon Coolpix 4500 in macro mode, shooting through an Orion Sirius 32mm Plossl and a Sky-Watcher 130N Newtonian reflector.


Galilean Nights!

October 23, 2009

Yarf! How’d I miss this one?

As part of IYA 2009, last spring astronomers around the world, both amateur and professional, hosted a weekend of stargazing called 100 Hours of Astronomy. The first two nights were clouded out for me, and I knew I’d be out of town for the fourth, but the third cleared up nicely. So I took my little telescope downtown, set it up in the public square, and ended up showing the first quarter moon to 144 passersby. That was my first experiment with the time-honored tradition of sidewalk astronomy: setting up a telescope in a public place to show the wonders of the heavens to whoever happens by–for free.

Since then I’ve tried to get downtown with the scope once or twice a month. Most people are happy to take a look and even happier once they have. A lot of folks tell me that it’s their first time looking through a telescope, and usually at least one or two people tell me that it was the highlight of their evening.

So it’s completely ridonkulous that I haven’t blogged yet about Galilean Nights, which is going on right now. The 100 Hours of Astronomy event was so successful that the organizers of IYA 2009 decided to do it again. Starting yesterday and running through tomorrow (Saturday) night, amateurs and pros everywhere are hitting the streets and the web with the goal of getting as many people as possible to do something very simple: look through a telescope. The moon is waxing, Jupiter is riding high in the southern sky, and if the weather doesn’t cooperate there are opportunities to do some remote observing.

Having somehow forgotten about the big show, I took my scope downtown last night anyway, just because that’s what I do at this point in the lunar cycle. Weeknights are kinda slow and in the space of an hour I only saw 22 people. I was back out tonight, and got 79 visitors. But it’s not about numbers, it’s about connecting with people and connecting people with the sky, and I had a grand time both nights. Sometimes the slow nights are best, you get more time to chat with folks. Not everyone wants to look, and that’s okay. But those that do–kids, grandparents, teenagers, whoever–everyone is moved by the sight of the moon and planets.

So here’s a sort of meta-mission assignment for you: if you have seen the moon or Jupiter (or whatever looks nice when you find this, my visitors-from-the-future) through your binoculars or telescope, share. Maybe you have a child or significant other that has never braved the cold and dark to stargaze. Maybe there’s a kid across the street or an elderly neighbor down the road that has never looked through a telescope. Maybe you’re lucky enough to live somewhere with a safe public place nearby. Doesn’t matter if your telescope is fully tricked out or fully humble, or if you don’t know exactly how far away Jupiter is. Sidewalk astronomy isn’t about giving people all the answers–it’s about giving them access, to something that belongs to all of us, but that they might never have seen before.

My first night out with the scope, I was nervous and fumbling and could hardly bring myself to ask the first person walking by, “Would you like to see the moon?” The guy stopped and looked, and what he said wasn’t printable (this is a family establishment; use your imagination), but it was gratifying. And I was off and running.

Go have fun!