Archive for November, 2009

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Astronomy Quote #2

November 10, 2009
M33colormosaic5LL_gendler_full

M33, the Triangulum galaxy, with pink star-forming regions and bluish clusters of newly-formed stars.

Once the sky was fully dark I had a look at the Triangulum galaxy, which at a distance of less than three million light years from Earth is a local object by intergalactic standards. Its rangy spiral arms, tangled with glowing clouds of gas, spilled out beyond the field of view. As often happens, I was struck by the fact that all of these things, unimaginably big or small or hot or cold as they may be, really are out there. Like giant squid or loaves of French bread–and unlike, say, postmodernism or public opinion polls–they confront us with the regality of the materially real.

– Timothy Ferris, Seeing in the Dark, p 64

 

Photo from APOD.

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Galileo Club, Part 3: Callisto in eclipse

November 8, 2009

There were two chances to see a Galilean moon entering or exiting Jupiter’s shadow from California tonight. At 6:22 PM Europa came out of the planet’s shadow, and at 8:50 Callisto went into it. I missed the first one but caught the second one.

I cheated a little bit; in addition to observing the disappearance of the moon at under 20x as required by the rules, I also photographed it at higher magnification in my 6″ reflector.

Now, when I first started observing, there were four little moons, two on each side of Jupiter, and as I watched, the inner one on the right got dimmer and then disappeared. But that requires a little unpacking. If you punch up Jupiter this evening in Stellarium or Celestia (follow the links on the right to download ’em if you haven’t already–they’re free), you’ll see that Callisto was the inner moon on the left as viewed from Earth. It was the inner moon on the right in the telescope because Newtonian reflectors rotate the image by 180 degrees. No big whoop, but if you watch the un-flipped version in Stellarium, the mechanics of the process are a lot clearer.

Callisto eclipse diagram

If you face south to see Jupiter, the sun is off to your right, having just set. That means the shadow of Jupiter forms a cylinder sticking out into space to the left of the planet as viewed from Earth. Since most stuff in the solar system orbits in a counter-clockwise direction* when viewed from above (Earthly north), Callisto must be on the far side of Jupiter from Earth. Callisto came out from behind the planet (1), was briefly visible from Earth, then entered the planet’s shadow (2), and will re-emerge in a little less than two hours (3).

* Neptune’s largest moon, Triton, is a notable exception, and its backward motion indicates that it is almost certainly a captured Kuiper Belt object and not a “true” moon. In fact, it is possible that all of Neptune’s moons are captured objects.

So how did the pictures turn out? Well…the listed time of 8:50 PM turned out not to be the midpoint of the entrance of the moon into the shadow, but the  completion. Which I guess makes sense, but I was prepared to start my observations 10 minutes early and run 10 minutes after. In fact, by 8:40 Callisto was already noticeably dimmer than the other moons, and at 8:50 the show was over. “Noticeably dimmer” in the eyepiece means “almost impossible to photograph”, at least with my setup (Orion XT6 telescope, 25mm Sirius Plossl eyepiece, and Nikon Coolpix 4500 camera). I thought I had missed it completely. My only shot of Callisto this evening:

Callisto 1 - nothing to see

Can’t see it? Neither could I. But I blew out the contrast and look who showed up, if only just:

Callisto 2 - ugly but there

By using that image as a template, I was able to copy, paste, and lightly sharpen my best Jupiter image of the evening, and replace the moon blobs with tiny little brush-dots that approximate their actual size and brightness, to create this much prettier and more representative, but less real, image:

Callisto 3 - too pretty to be real

Jupiter looks lousy compared to previous efforts because I was looking through most of the LA light dome and attendant haze, but still: eat yer heart out, Galileo. One required task down, ten to go!

(If you haven’t bagged a moon eclipse yet, there are still several opportunities this week.)

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Hack that scope

November 8, 2009

A time-honored tradition in amateur astronomy is amateur telescoping making, or ATMing. For many decades, most people didn’t buy their first scope, they built it, sometimes using optics or mirror grinding kits supplied by Edmunds and others, sometimes just hacking with whatever they happened to have lying around.

I’ve messed around with this a little; a couple of years ago I bought a National Geographic brand 76mm reflector at Target at a deep, deep discount. The scope had good mirrors but the mechanics were terrible; in particular, the eyepieces seemed to have been designed by someone who wanted to discourage people from looking skyward. Why, National Geographic, why? The old rule still applies: never buy a telescope anywhere that sells underwear (that includes Toys ‘R Us!). Unless, like me, you only want the scope for its parts, to build it into something better, and you can get it super-cheap.

Anyway, the full saga of the oft-rebuilt 76mm reflector will be a story for another day–not least because I am contemplating rebuilding it for, let’s see, the fourth time.

Outlook

Today I’m writing to bring to your attention this very cool rig built by frequent commenter David DeLano. It’s basically a board with three holes, but this  simple device allows him to mount his GalileoScope (tricked out with a diagonal and helical focuser from StellarVue) and his SkyScout (a handheld computerized planetarium-star pointer-thingy) on the same tripod. And he’s thinking of adding binoculars on top! His inspiration came from this cool tripod adapter from astronomy hacker extraordinaire, Rob Nabholz.

What do you have laying around the house that might make your observing life easier? Give it a think, and if you come up with any cool ideas, let me know!

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Galileo Club, Part 2: Jupiter’s Moons in Eclipse

November 6, 2009

Galilean_Moons

Task #4 for the Astronomical League’s Galileo Club:

4. 1612 – Jupiter’s moons in eclipse: The objective is to show that in addition to the moons being occulted by Jupiter, they also travel through Jupiter’s shadow and are eclipsed. Observe and sketch, noting the timing, one of Jupiter’s moons during an ingress or egress with Jupiter’s shadow. Callisto or Ganymede is the most dramatic. Two observations should be done.  One should be close to when Jupiter is at opposition. The second should be done when Jupiter is at quadrature (90 degrees from the sun). Note how close to the planet the moon is when the event occurred. (Editor’s note: At least two observations and timings are required.)

This is one of the ones that needs to be done Real Soon Now, because the eastern quadrature of Jupiter is this coming Tuesday, November 11. After this Jupiter is going to keep heading west and then disappear into the sun’s glare for a while. Western quadrature won’t be for another six months, and then you’ll have to either get up real early or stay up real late to catch it; western quadrature is equivalent in terms of sky position to last quarter moon.

Unless you want to spend all night watching, waiting, and hoping, you’ll want some idea of when to observe to see the entry or exit of a moon from Jupiter’s shadow. So here’s a list of ingressions and egressions for the next week, taken from Sky & Telescope’s Jupiter moon calculator. Sometimes there is an exit with no entrance, because the moon in question went directly behind the planet as seen from Earth; that’s an occultation rather than an eclipse. Everything is listed both by Universal Time (UT), equivalent to Greenwich Mean Time or London time, and Pacific Standard Time (PST). If you live somewhere else, you can look up your offset from UT at this helpful site.

I’ve never watched one of these events so I don’t know how long they take. Probably worthwhile to start observing 15-30 minutes ahead of the stated time and keep watching until you know it’s over. That blows my titular goal of providing things you can do in 10 minutes, but…whatcha gonna do? Feel free to leave a comment if you make a successful observation. Photo borrowed from here.

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Saturday, November 7, 2009
18:18 UT (10:18 AM PST), Io exits eclipse by Jupiter’s shadow. Daytime for US.

Sunday, November 8, 2009
02:22 UT (6:22 PM PST), Europa exits eclipse by Jupiter’s shadow.

Monday, November 9, 2009
04:50 UT (8:50 PM PST), Callisto enters eclipse by Jupiter’s shadow. Sunday night in the US!
09:30 UT (1:30 AM PST), Callisto exits eclipse by Jupiter’s shadow.
12:48 UT (4:48 AM PST), Io exits eclipse by Jupiter’s shadow.

Tuesday, November 10, 2009
08:52 UT (12:52 AM PST), Ganymede enters eclipse by Jupiter’s shadow.
12:32 UT (4:32 AM PST), Ganymede exits eclipse by Jupiter’s shadow.

Wednesday, November 11, 2009
07:16 UT (11:16 PM PST), Io exits eclipse by Jupiter’s shadow. Tuesday night in US!
15:40 UT (7:40 AM PST), Europa exits eclipse by Jupiter’s shadow. Daytime for US.

Friday, November 13, 2009
01:46 UT (5:46 PM PST), Io exits eclipse by Jupiter’s shadow. Thursday evening for US, probably too early for PST.

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Get your Mars on

November 6, 2009

Victoria crater small

The Boston Globe’s The Big Picture feature covers Mars today, thanks to the HiRISE camera on board the Mars Reconnaissance Orbiter. See craters, dunes, water-eroded gullies, dust devils, and the tracks of our rovers, courtesy of what is still the coolest non-Hubble camera in existence.

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Extended Mission: AL Galileo Club

November 4, 2009

Galileo observing

All right, it’s been a long time since I’ve given you any homework. Heck, it’s been a long time since I’ve given myself any homework. Joining the local astro clubs also made me a member of the Astronomical League, which has loads of cool observing projects available. If you complete an observing project, you get a pin and a certificate, and I want some bling.

(Aside: if you’re interested in astronomy but not a member of a club, find one nearby and check it out. Most clubs will happily let you sit in for free for a meeting or two. The two I’m involved in both have annual family dues of $30, and I imagine most clubs’ dues are not wildly off from that. It’s a small price to pay for the companionship and education you’ll get from fellow astronomers.

If there is no club nearby, the stand alone Astronomical League dues are also $30, and if you don’t want to spend any money, you can still download the lists for almost all of the observing clubs for free.)

Observing lists are good. They give you tangible goals, and a way to measure your progress as you develop your skills. Perhaps most importantly, they give you something to point the scope at. The sky is chock-full of good stuff, but if you don’t know that it’s there or how to  find it, eventually you are going to run out of things to do. If you find your observing getting stale, maybe it’s time to try something new.

So, given that it’s the International Year of Astronomy and that we’re all following in the footsteps of Galileo, what better observing list to start with than the Astronomical League’s Galileo Club? The goal is to repeat Galileo’s observations of the heavens. There are 11 required tasks, and two optional ones. The optional tasks are to observe and sketch an aurora, which is only an option for people at sufficiently high latitudes, and to observe and sketch a naked-eye supernova in the Milky Way galaxy. I’m guessing that last one was included a bit tongue in cheek; as the instructions state, “It should be noted that the last time a supernova was visible in the Milky Way galaxy was in the early 1600’s when Galileo observed one.”

Now, the Astronomical League doesn’t pass out those pins and certificates for nothing. Some of the tasks are comparatively easy, but some are fairly involved (in terms of effort, not equipment), and several require making observations at particular times of the year. If you start now, you can’t possibly finish before next summer, not because you’ll be slammed for the next 9 months, but because one of the observations can’t be made any sooner. So if you’re in, you’re in for the long haul.

Gear

The only requirements regarding equipment are as follows: “All observations must be done at a magnification between 10 and 20. Either binoculars or a telescope may be used. The instrument should be mounted to provide adequate stability. Go-to equipment is allowed.”

Let’s break it down, in reverse. Go-to equipment means computerized telescopes that do the finding for you. I’m surprised they allow that for this club; I think it defeats the purpose of the exercise and I’m going to pretend that it doesn’t exist.

Mounting the instrument shouldn’t be a problem. If you’re going to use a telescope, presumably it came with a mount. If you’re using binoculars, all you need is a cheap tripod and about three bucks worth of hardware; see instructions here.

The first requirement is the toughest: all observations have to be done between 10x and 20x magnification. This is tough because some telescopes can’t go down that low with normal eyepieces. For example, my little Mak has a focal length of 1250mm. The longest eyepiece is can accept is probably a 40mm Plossl (which I don’t own), which would still yield a magnification higher than 30. What to do, what to do? One option is to use a scope with a fairly short focal length, which includes loads of small refractors (from the $20 Galileoscope to thousand-dollar APOs) and tubby little reflectors like the Firstscope and Funscope (both $50), Astroscan, and Starblast.

Another option is to just use binoculars. If you don’t already have some, you can get a decent pair of 10x50s for about $25.

What else will we need? Most of the tasks include the word “sketch”. Sketching at the eyepiece is a good way to build observing skills and it’s probably something we should all be doing more of anyway. But what to sketch on? Lots of folks like to use preprinted observing log sheets that have room to note the date, time, equipment, sky conditions, and observations of the target, plus a circle in which to draw the object of interest. You can find nice PDF versions online for free here and here. The GalileoScope Observing Guide also includes a log sheet, and you should check that out anyway, whether you’ve got a GScope or not.

Schedule

Okay, with optics and observing logs hopefully squared away, we still need a plan. We can’t see everything tonight, or even this month. The nature of each task will determine our schedule:

  1. Naked eye supernova in the Milky Way. Good thing this one is optional; an acceptable star might pop tonight or not for centuries.
  2. Moon features; show that the moon has mountains and valleys. Any time that is not too close to full or new moon is fine, so probably 2/3 of the nights on any given month. Check out the moon phase thingy on the right to see what’s going on and plan accordingly.
  3. Follow Jupiter’s moons through one cycle of their orbits. That’s 17 days of observations. Jupiter is a little farther west every evening and we’ve only got a couple of months before it’s lost in the sun’s glare, so start this one ASAP.
  4. Observe one of Jupiter’s moons disappearing into the planet’s shadow or emerging from it. Two observations are required, one at opposition (when Jupiter is opposite the sun in the sky) and one at quadrature (when Jupiter is 90 degrees away from the sun in the sky). Sky & Telescope, Stellarium, Celestia, and a host of other resources will tell you what to look for and when, but look soon, because eastern quadrature is Nov. 11, one week from today. This one is likely to be tricky so I’ll do a follow-up post on it in the next week, promise (hey, I did!). The next opposition isn’t until next summer, so Jupiter may set the lower bound on how soon one could possibly finish the Galileo Club, starting right now. (That would already be sorted if I’d gotten started a few months ago, but coulda woulda shoulda…)
  5. Orion’s head nebula. This isn’t a “nebula” in the sense we use it today, as a giant ball of gas and dust out in space, but rather a nebula as it was understood in Galileo’s time: a fuzzy patch of light in the sky. In this case, observing the fuzzy patch with binoculars or a telescope will reveal that it is composed of stars. Orion is up by about 10:00 and will be higher and better seen at sundown in a couple of months, so this one can be done anytime between now and, say, March or April.
  6. Praesepe nebula. Another naked eye fuzzy patch (only under dark skies these days, I’m afraid) that will resolve into a pretty star cluster with binos or a scope. Anytime in the spring.
  7. Pleiades nebula. Ditto. Up not long after dark right now, anytime in the next few months is fine.
  8. Saturn’s “ears”. The rings look like ears at the low magnifications available to Galileo (and to us, given the rules of the project). Anytime in the spring. Opposition will be in late March.
  9. Venus phases. These need to be tracked from close to inferior conjunction, when Venus is a very big crescent, to close to superior conjunction, when it is a small dot. Venus is currently a morning star and it’s about to get lost in the Sun’s glare. It will re-emerge east of the sun in 2010 and become an evening star, so the best time to start tracking this is in February or March.
  10. Sunspots. This one is tricky, both in terms of equipment and schedule. The instructions say to make the observations using a filter. Well, filters are expensive and Galileo didn’t use them, so I intend to do this as he did: by using a small telescope to project an image of the sun on a white card (don’t look right at the sun with unfiltered optics unless you’re ready to give up the burden of sight). The tricky scheduling part is that we’re in a deep solar minimum and there has only been one sunspot in the past year, so we’re at the mercy of Sol on this one.
  11. Comet. I know there are several floating around regularly within the reach of small telescopes and even binoculars, but I haven’t observed a comet since 17P Holmes a couple of years ago (which was awesome, BTW). Gonna rain check this one for a while.
  12. Neptune. Observable right now, not far from Jupiter. Along with the Jupiter moon eclipse at quadrature, this is the one most needing immediate attention. Standby for directions (also posted).
  13. Aurora. Optional. I saw it in Montana on a dinosaur dig about a decade ago. Very pretty if you get the chance.

All right, that’s all for now. Gather your gear, print off some log sheets, and I’ll get crackin’ on those Jupiter moon timings and on finding Neptune. There are also some pretty end-of-summer objects we need to see before they plunge beneath the western horizon. Stay tuned.

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New stuff

November 2, 2009

skymap_smallHere’s something that you need, or even if you don’t need it need it, you’ll probably find a use for: free monthly sky maps, with a chart on the first page and an observing list broken down by naked eye, binocular, and telescope objects on the second page. Everything on the second page is noted on the chart on the first page.  Pretty ridiculously awesome. Expect me to reference these a lot in upcoming missions.

Also, Scientific American has an in-depth report on Galileo and IYA2009. Worth checking out. And speaking of, I took my 4-year-old to what he calls the “Griffick Park Ugzerbatory” yesterday. Here he is with a replica of Galileo’s telescope.

Galileo telescope

Believe it or not, new mission coming soon. Hang in there.