Archive for the ‘Galileo’ Category


The mountains of the moon, and the moons of Jupiter

February 15, 2012

My latest efforts at white-trash astrophotography (or, if you prefer, afocal projection photography, or digiscoping), wherein I hold my digital camera up to the eyepiece of my telescope and take pictures:

The moon last night, at last quarter. I love this phase because the mountains that form the eastern rim of Mare Imbrium–the immense incomplete circle in the moon’s northern hemisphere–are still catching the light of the setting sun, creating an arc of light in a sea of darkness. Galileo saw the same thing with his 1-inch telescope 403 years ago, and correctly inferred that the lights in the darkness were mountaintops on the moon, catching either the first (when waxing) or last (when waning) rays of the sun, and that therefore the moon was not a perfectly smooth sphere, but a world with similarities to our own.

And, hey, it looks pretty. I like how the arc-of-light-in-darkness motif is repeated by the smaller craters along the terminator to the south of Mare Imbrium.

Jupiter and the Galilean moons, tonight. As with previous efforts (see here and here), this is a composite shot. To get the moons to show up at all, I had to completely overexpose Jupiter,  so this is a combination of two images. The order of the moons from right to left is also, by chance tonight, their order from closest in to farthest out from Jupiter: Io (by itself on the right), Europa, Ganymede, and Callisto. This is only the second time I’ve gotten Jupiter and all four kids in one shot; often one of the little bleepers is off in Jupiter’s shadow.

All photos taken with a Nikon Coolpix 4500 digital camera, Orion Apex 127mm Maksutov-Cassegrain telescope, and Orion Sirius Plossl eyepieces (32 mm for moon, 25 mm for Jupiter and family).


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.


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.


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.


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.



Observing Report: Mt Wilson!

August 22, 2009
1 - LA from Mt Wilson 1200

The LA Basin from Mt Wilson. The yuckiness is partly fog, partly smoke from forest fires, and partly the exhaust of a few million automobiles.

Looking toward the ocean at sunset. The fog helped suppress light pollution from LA while we were observing.

Looking toward the ocean at sunset. The fog helped suppress light pollution from LA while we were observing.

The antenna forest outside the observatory entrance. The top of the solar telescope tower is visible in the distance on the left.

The antenna forest outside the observatory entrance. The top of the solar telescope tower is visible in the distance on the left.

The immense dome of the 100-inch Hooker telescope looms through the trees like a mountain.

The immense dome of the 100-inch Hooker telescope looms through the trees like a mountain. Edwin Hubble used this scope to discover the redshift of distant galaxies and the expansion of the universe.

A closer look at the solar telescope, which was the first operational telescope on Mt Wilson. Hale used this scope to discover the Sun's magnetic field.

A closer look at the solar telescope, which was the first operational telescope on Mt Wilson. Hale used this scope to discover the Sun’s magnetic field.

We started observing with the Mt Wilson 60-inch at about 8:15 PM Wednesday evening. We aimed at Arcturus first, just to make sure that everything was in good working order. Then we split a nearby double star, Epsilon Bootes. After that we got started in earnest. Our first deep sky object (DSO) was M13, the great globular cluster in Hercules. This vast sphere of several hundred thousand stars was discovered by Edmund Halley in 1714. It has special significance for me because it was the first object I observed through the Great Lick Refractor on September 15, 2007, on the night that my lifelong interest in astronomy finally caught fire. In the 60-inch telescope M13 filled the field of view. It almost exhausted the eye, there was so much to  look at.

Here we go--the dome of the 60-inch telescope.

Here we go–the dome of the 60-inch telescope.

Then we went outside at about 9:20 to watch an Iridium flare–the sudden brightening of a giant solar panel on one of the Iridium communications satellites. It was the first time I’d seen one, and it was pretty cool.

Finally, the big gun itself. When you're in the dome, it's about all you can look at.

Finally, the big gun itself. When you’re in the dome, it’s about all you can look at.

Then it was back inside for more telescopic goodness. Post-flare we looked at NGC 6543, the Cat’s Eye Nebula. This is another summer to early autumn classic, and another object that I first viewed through the Lick Refractor almost two years ago. It was even better in the 60 inch telescope, a visibly S-shaped swirl of green with hints of structure  around the central star.

Arf--dunno how this caught me without a smile. I had one plastered on for the entire evening.

Arf–dunno how this caught me without a smile. I had one plastered on for the entire evening.

Then it was on to Jupiter, which was huge. The visible Galilean moons were not just points of light in the eyepiece but little spheres; they looked like the worlds that they are. An odd side effect of looking through the giant telescope was to make us appreciate our own scopes more. For picking out detail on nearby objects like Jupiter, atmospheric turbulence is often more limiting than telescope optics. I’m not going to lie and claim that the views in my 6-inch telescope are as good as the views through the Mt. Wilson 60-inch–but on Jupiter I reckon that the 60-inch scope delivered twice as much detail as my scope, rather than the ten times more detail that optical theory would suggest. If the 60-inch was up on Mauna Kea and not plagued by light pollution, smog, and turbulence, it would perform a lot better–as would any telescope. I’m not complaining. Just observing that although our backyard scopes don’t show nearly as much as big observatory scopes, they still show quite a bit.

When the big scope is pointed straight up you can sit in a chair to observe, but most of the time we were up and down the ladder to reach the eyepiece.

When the big scope is pointed straight up you can sit in a chair to observe, but most of the time we were up and down the ladder to reach the eyepiece.

There was another way in which the views Wednesday night made me appreciate my own telescopes more. Galileo discovered the moons of Jupiter, and he never saw them through a telescope with a diameter of more than an inch. The finderscope that I use on my airline-portable travel telescope has a bigger aperture and sharper optics. And yet Galileo changed the world with the observations he made through his tiny, optically terrible telescope. To get to see the Galilean moons as little worlds in the 60-inch reinforced how ridiculously fortunate all of us are to have such nice tools available.

When you go downstairs from the observing deck to use the restroom, you go past a bank of lockers. The names include Zwicky and Minkowski. This one belonged to Edwin Hubble.

When you go downstairs from the observing deck to use the restroom, you go past a bank of lockers. The names include Zwicky and Minkowski. This one belonged to Edwin Hubble.

Speaking of tools, we got to take turns photographing Jupiter through the eyepiece. As is often the case, I got my best picture in the first few snaps. I was so busy previewing my pictures and talking with the other visitors that I completely missed the next object, planetary nebula NGC 7662, the Blue Snowball. Many thanks to Tom Mason, our scope driver, for sharing the photo below.

Planetary nebula NGC 7662, the Blue Snowball. It consists of vast rings of gas blown off by a dying star. Our sun may look like this in about 5 billion years.

Planetary nebula NGC 7662, the Blue Snowball. It consists of vast rings of gas blown off by a dying star. Our sun may look like this in about 5 billion years. This photo is by Tom Mason, our scope driver for the evening.

Faint DSOs require light-gathering ability primarily and not the resolution of fine details. The 60-inch totally blew away any backyard scope on planetary nebulas. After the Blue Snowball we checked out another, even more famous planetary nebula, the Ring Nebula or M57. In backyard scopes it looks like a perfect little doughnut of gray smoke. In the 60-inch it was a huge and green, with threads of gas and dust visible in the middle. I could even make out the central star, which is a legendarily tough object to detect visually.

After the Ring we went back to Jupiter, and then on to Neptune, which is currently close by Jupiter in the sky, just as it was for Galileo four centuries ago. Neptune is incredibly distant, 4.5 billion kilometers away. That’s 30 times farther from the sun that we are, and 6 times farther away than even Jupiter. Even in the 60-inch Neptune was small, but it was visibly a sphere, which is quite an achievement for any Earth-bound optical telescope. Coming down the ladder, I had to remind myself that Neptune is now the most distant planet in the solar system, since Pluto was (correctly, IMHO) demoted to dwarf-planethood.

The final object I observed through the big gun was the Saturn Nebula, NGC 7009, another planetary. It looked much like its namesake. Click on the link above, get 10 feet back from your computer, and you’ll have a pretty good idea of what I saw through the 60-inch.

The highlight of the evening for me: Jupiter and its moons. Three of the four Galilean moons were visible in the eyepiece, but this photo only shows one: Io, on the upper right.

The highlight of the evening for me: Jupiter and its moons. Three of the four Galilean moons were visible in the eyepiece, but this photo only shows one: Io, on the upper right.

By the time I’d gotten down the ladder from looking at the Saturn Nebula, it was 3:00 AM and time for me to skidaddle; I had to teach Thursday morning and that meant getting at least a little sleep. On the way out, though, I did stop long enough to enjoy a view of the newly-risen Pleiades in my binoculars. You can do the same if you’re willing to get up in the middle of the night–or you can look forward to a Pleiades mission here in a few months. It all comes back around.

Lots of things came back around for me Wednesday night. M13 and the Cat’s Eye ushered me into astronomy, and it was great to revisit them with two years of knowledge and experience under my belt–as well as 24 more inches of aperture.

What I wanted most from the evening, though, was to photograph Jupiter and its moons. They were the first things I ever viewed through a telescope, in my high school astronomy class. They were also among the first things that Galileo observed with his telescope, 400 years ago this December. I wish he could see how far we’ve come–and how much we owe him.

Finally, a huge thank you to the Pomona Valley Amateur Astronomers for inviting me along and being such gracious and interesting hosts. I had the time of my life. If you ever get the chance, go.


In the footsteps of Galileo redux

August 18, 2009


Hoo boy. So all of three days ago I started this blog with a post entitled, “In the footsteps of  Galileo”, about Galileo’s  achievements, IYA 2009, and starting out in astronomy (image above from Wikipedia).

All of three minutes ago I discovered that the Astronomical League has an IYA 2009 project called, “In the footsteps of Galileo”, with instructions for replicating Galileo’s discoveries for those starting out in astronomy. It’s a cool project, and all it takes is a pair of binoculars and some patience (or fortitude; the Pleiades [#4 on the list] rise about midnight right now and aren’t what you’d call “well placed” until 2 or 3 AM).

The duplicated title is a coincidence–Google lists almost 3000 hits for the exact phrase “in the footsteps of Galileo”–but a fortunate one, because the “Footsteps of Galileo” project hits some of the best stuff I was planning on covering on this blog anyway. In particular, I’ve got some posts lined up on how to take the binoculars you probably already have and make the most of them for stargazing. Stay tuned for more–or, if you’re chomping at the bit, download the “Footsteps of Galileo” observing guide, dig the binoculars out of the closet, and get going (don’t forget Stellarium if you need a little help finding things).

If you’re  looking for something just a little more challenging, the Astronomical League’s Galileo Club includes 12 projects for small telescopes or serious binoculars. You probably will need something with higher magnification (15x-20x) than your average birding binos for those, but even a very small telescope should be adequate. Like, er, this one (shown below), which people have been having a lot of fun with despite, or perhaps because of, its $20 price tag.


Both AL projects are also listed on the right under Observing Lists. “In the Footsteps of Galileo” appears as “5 binocular targets for beginning stargazers”, and the Galileo Club appears as “12 objects for binoculars and small telescopes”.

Have fun!


In the footsteps of Galileo

August 15, 2009


This year, 2009, is the International Year of Astronomy. IYA2009 celebrates the 400th anniversary of the first observations of the heavens with a telescope, by Galileo in 1609.

It’s staggering how much Galileo did. If you look at the stuff out there that can’t be seen with the naked eye, he discovered a vastly disproportionate amount of it. Let’s break it down:

Milky Way

GALILEO, 1609-1612
Sunspots (= sun not perfect)
Moon craters and mountains (= moon not perfect)
Venus phases (= Venus circles sun, not Earth)
Jupiter’s moons (= bodies circling Jupiter, not Earth)
Saturn “appendages”
“Star” next to Jupiter (later shown to be Neptune)
Milky Way composed of stars (stars vastly more numerous than previously suspected)
Other bright patches composed of stars (ditto)

Saturn “appendages” are rings – Huygens, 1655
Saturn’s moons – ditto
Uranus – Herschel, 1781
Ceres (first asteroid) – Piazzi, 1801
Neptune recognized as a planet – Galle, 1846
Asteroid belt – several, 1850s
Pluto – Tombaugh, 1930
Rings and moons of outer planets – Voyager probes, 1970s-1980s
dwarf planets beyond Pluto – Mike Brown, 1990s-2000s

Basically, the eras are “stuff everyone knew from when we lived in caves”, “Galileo figures out most of how the solar system works in the space of three years”, and “working out the details”.


It’s all the more impressive when you realize that he was stuck with a 1″ telescope with a field of view of perhaps 5 degrees and a maximum magnification of 20x that, in the memorable words of someone I’ve forgotten, “suffered from every aberration known to optics”. As much as amateur astronomers complain about “department store trash scopes”, the worst plastic monstrosities sold as ‘educational toys’ are still about a thousand times better than what Galileo had to work with for his entire life.

Galileo did more than any other single person before or since to give us a perspective on the universe and our place in it. It’s a perspective that most people have little or no firsthand experience of. In an age when satellite TV is more than a generation old, mobile phones and dashboard computers can guide you around the world using GPS, remote controlled robots explore the surface of Mars, and mankind’s orbital population never drops below 6 (on the International Space Station), average citizens are strikingly disconnected from the wonders of the night sky. Too many people assume that looking up is the exclusive domain of professional astronomers, or that it’s too expensive, or too time consuming, or impossible under the glare of city lights.

2009-04-27 lights at night

None of these assumptions is accurate.

My ambition for this blog is to invite you to be at home in the universe. During the day we see only the world around us, but when darkness falls we can look out, see firsthand, and really get a gut-level understanding of our place in the cosmos. You can learn your way around the sky without spending a dime, and you will never be lost again. An ordinary pair of binoculars, which you probably have stashed in the closet already, will show you most of the wonders that first excited Galileo four centuries ago. If you decide to get a telescope, they are better designed, easier to use, and less expensive than at any time in history.

The slogan of IYA2009 is “The universe, yours to discover.” It is yours to discover, and it doesn’t take a lot of time or money to learn your way around the night sky and see the best and brightest that the heavens have to offer. The journey begins whenever you go out at night and look up. If you’re not sure where to start, that’s okay–that’s what this blog is for. Let’s go!