Sunday, November 09, 2008


The Silicon Sky Part I: Planetariums for PCs

Your ol Unk Rod ain’t gonna pretend he’s the most computer-savvy dude out there. Much of what goes on inside those mysterious boxes on the desktop is still a mystery to me. So how dare I write a piece about amateur astronomy software?

Well, I might not know the details of how a computer and a program work all their magic, but I darned sure know how to use ‘em—in my simple and simple-minded fashion, anyhow. I’ve been onboard the astronomy computer revolution since I got my hands on Sky Travel, a proto astronomy program for the Commodore 64, in the mid 1980s. It wasn't very useful, but it was fun.

My acquaintance with software that can actually help you find your way across the sky began one day when I was strolling through Books-a-Million in the mall. I noticed a program called Skyglobe in a bin of shareware 5.25-inch floppies (you old folks will remember them). I went from that to the late and mostly unlamented Stargaze (ground-breaking in its own way, nevertheless), and, before I knew it, my hard drive was full of more astro-ware than humans should be allowed to have. If it’s a Win PC program, I’ve probably used it, and so, I feel qualified to give you my greatest hits here.

Actually, this will be Part One of my greatest hits. First time out we will take a look at planetarium programs. Whatsits a whosits? A “computer planetarium” is just what it sounds like; a program that simulates the night sky on your computer screen. This may range from a simple display of the constellations and bright stars designed to appeal to the kids, to a gen-u-wine star atlas on disk. Planetariums are not the only style of astro-ware, there’re also the “planners” we’ll talk about here in a week or three, but planetariums are a good place to start: they are what pops into most amateur astronomers’ minds when they think “astronomy software.”

Planetariums and planners, eh? That still leaves open the question of why you’d want to use either. Who would want to drag an expensive laptop PC onto a damp observing field? Sure, zooming around the sky indoors with something like Celestia can be Real Fun, but why would anybody want to fool with computers—or even computer printouts—in the great outdoors?

Well, for those just starting out to conquer the deep sky, Sky Atlas 2000 is more than adequate. At least you’ll never have to worry about its batteries pooping out. But what happens when you get beyond the M31s and M13s? When you find yourself chasing Einstein’s Cross and M31’s multitudinous globs?

Even if you are not quite that sanguine, you may eventually come to the point where good ol’ SA2000 and similar atlases don’t contain everything you want. Or even much of what you want. You can go deeper and stay with "print;"  the magnitude 11 Millennium Star Atlas (MSA) has a lot of Good Stuff in it, but, believe you me, this detail level is where a computer program becomes much more practical. Using a work like MSA involves lots of page flipping (three fat volumes of thin paper). You may spend more time looking for the target in the book than you will looking for it in the sky. Even the simplest planetariums have search features that make finding IC Umptysquat a no-brainer. There’s also the fact that even el cheapo planetariums go way deeper than MSA. Yes, Millennium contains 1,000,000 stars and 10,000 deep sky objects. Howsomeever, even the meekest and mildest planetarium may sport 10,000,000 stars and 100,000 DSOs.

You still don’t want to tote an expensive laptop onto a wet observing field? Well, beyond the fact that laptops ain’t exactly expensive anymore, and that a used one more than adequate for running most astro-ware can be had for a cupla hundred George Washingtons, you don’t have to tote your laptop onto the field to enjoy its benefits. If you’ve got a good idea what you will be looking at or at least where in the sky you will be looking, you can enjoy many of the rewards of the PC astro revolution by just printing hard copy charts and carrying them with ya. Most good planetariums today can print charts of almost typeset quality, and, again, they will go far deeper than the equivalent page of SA2000 or MSA. Try to print on a laser printer if possible, since an inkjet's output will become an illegible mess in about two heartbeats under heavy dew, even if you’ve got it in page protectors.

Now, without further ado, here are my picks for the Best of the Best. These are the planetarium programs I’ve used the most and loved the most.

Cartes du Ciel

I once asked “CdC” author Patrick Chevalley why he didn’t try to make some money off his creation instead of giving it away as freeware. His response? “Rod, I’m an amateur astronomer, and I’d rather see amateur astronomers spend their money on new eyepieces than computer programs.” That oughta tell you something about Patrick’s commitment to the astronomical community. This commitment also shows in the quality of his program. No, Cartes does not offer photorealistic skies; its depiction of the heavens is a simple one, but it is a clear one, something welcomed by me at 3 o’clock in the a.m. It also does just about anything you would ever want a planetarium to do.

The complete program package includes tens of thousands of deep sky objects, and an almost unlimited number can be added to that. Since CdC has been around and very popular for a long time, just about any astro-catalog you can think of, from the familiar PGC and PK to things like the DWB, has been formatted for this program. Still can’t find what you want? Patrick includes a utility that will allow nearly any catalog to be converted from ASCII to something CdC understands. Stars? As downloaded, the program package (the complete 15 megabyte version) includes the Tycho II, which is often more than enough. Cartes can also read-in the Hubble Guide Star catalog from a variety of different format CDs. Don’t want to mess with or pay for GSC CDs? One of the nicest features of Cartes is that if you have an Internet connection available (which is more often than not the case at big star parties in these latter days), CdC can download GSC stars for the current field as needed.

More and more Kats 'n Kittens want to (or think they want to) connect the laptop to the go-to scope and initiate slews with Mr. Mouse. How does CdC do there? Very well indeed. Seeing as how it uses the ASCOM telescope driver helper-program, Cartes can interface with just about any go-to rig under the Sun.

Stink-it-ups? Not many. Oh, if you want pretty, this is not the place to go, but that is the only majorly bad thing I can think of to say about this time and user tested application. Nits? Cartes is Patrick’s hobby, not his job, so development on Cartes (and his other program, Virtual Moon Atlas) tends to be slow and in fits and starts. The current Cartes release is v2.76, and has been for years. He has continued work on an even nicer v3.0, but it’s still in beta a fur piece down the road (though it’s perfectly usable right now). The fact that this is an avocation for the author does not translate into “lack of support,” however. Patrick runs a Yahoogroup for his program, and is almost always there to answer questions, squash bugs, and address all sorts of user concerns. Were I you, I’d definitely try Cartes du Ciel before plunking down coin for a commercial program.

Hallo Northern Sky

Hans Kleijn’s program’s name sounds weird (to this ol’ boy’s ears, anyhow), but it works like a champ, and is, if not quite as popular as Cartes, still one of the big three freeware planetariums. With good reason. This is an incredibly capable and mature tool. Like Cartes, there is little any observer would need to do that can’t be done with HNS. In addition to the usual fillips—millions of stars, tens of thousands of deep sky objects, and images for many of these objects—the program presents an even more clear and uncluttered UI (user interface) than Cartes du Ciel. One thing I particularly like is that requesting object information does not bring up a sky-obscuring window; instead details on the target are printed in the upper left corner directly on the sky display in unobtrusive fashion.

So what’s not to like? Not much. If you are concerned about aesthetics, you will find HNS’s sky display not just plain, but positively antique-looking. In addition, while many add-on catalogs are available, including a portion of the LEDA galaxy cat, catalog support for Hallo Northern Sky is not as extensive, from what I can tell, as it is for Cartes. As is the case with CdC, HNS users will need to download and install ASCOM in order to control a go-to scope with this program. Once that is done, however, HNS works exceedingly well in that regard. Verdict? Two enthusiastic thumbs up for this classy and classic planetarium.


If you want a freeware planetarium program and are concerned about aesthetics, HOOBOY do I have the software for you. Stellarium is the third member of the freeware planetarium triumvirate and has gained many, many fans due to its incredible good looks. Hell, the Stellarium sky is actually prettier than my own real (sodium pink) heavens. Now, a lot of folks like the idea of a near-photo-realistic depiction of the sky, but get a little skittish about glomming onto such a soft because they don’t have the latest 8 gazillion gigaflop laptop. Not to worry. Purty as Stellarium is, it still runs speedily even on many older machines. It is quite a trip the first time you “grab” the sky and drag it with your mouse…ahhh, so smooth and responsive.

Despite all the good things above, unlike CdC and HNS, I will not suggest Stellarium can be your sole tool if you are a working observer. Right now, "pretty" is most of it. While the program is well-equipped with stars (600,000 in the default package), it loses steam with the DSOs. Oh, it’s got all the Messiers, and it’s got all the NGCs and ICs (I think it does, but the number of DSOs in the program is not enumerated anywhere), but that is about it. Also, while the Messiers are depicted with honest-to-god images, other DSOs are merely spots. Galaxy symbols, for example, are just that, symbols, that do not depict size/shape/orientation. The program can control a scope with the aid of ASCOM, but this requires yet another add-on module, Stellarium Scope. Still, this program is beautiful and has come a long way in a short time.

How useful this one will be out in the field in the future depends on which way the authors go with it. If they go just a tad further in the observing direction, lotsa guys ‘n gals will quickly throw-over CdC and HNS for it. However, the developers are hinting they are actually more interested in developing Stellarium into something like Microsoft's WorldWide Telescope or Google Sky than turning it into an observer’s tool. Whatever they do, Stellarium will still be one of my faves, I’m sure—for indoor use at least.


With Megastar we come to “pay to play.” Yep, you’ll shell-out just o’er 150 pieces of silver for thisun. Is it worth it? I’ll say it is, if you’re a hardened deep sky observer, anyways. Megastar and I go way back. The first time I heard about it was in the early 1990s. And what I was hearing was impressive. Not only did Megastar have more DSOs than any other computer program (or print atlas) of the day, I was gobsmacked to learn it sported the whole Hubble Guide Star Catalog—a tool most amateurs didn't dream of possessing back then.

A search of the teeny-tiny ads in the back of Sky & Telescope revealed a blurb for Megastar, which, at the time, was marketed directly by its author, Emil Bonano. The only thing that stopped me from ordering it right then and there was the information: “Ships on fifty 3.5-inch floppies.” Fifty? That seemed a bit much to load successfully. What if floppy 39 failed? Luckily, CD ROMs was coming in by then, and it was not long before I was able to order a copy in that format.

Actually it was Miss Dorothy who did the ordering for me; since she thought it would be a nice Christmas present for her new husband. When she talked to Emil, she mentioned that and that scamp suggested they play a little joke on Unk. He shipped the program CD in a box from a program called “Expert Astronomer” (don’t ask). You can imagine how ol Rod struggled to look surprised and pleased on Christmas morn when he unwrapped the sucka. Miss D., sweet as she is, couldn’t bear to keep me twisting in the wind though, and soon said, “Just open it, you silly.” I’ve been happily using this “star atlas on disk” ever since.

Not that it is perfect. While the author has added some planetarium type tools over the years, this is still more a, yes, computer star atlas than a full fledged planetarium. Oh, there’s a horizon line, animation, and planets, but these things take a backseat to the depiction of faint stars and deep sky objects on a screen that is at least as plain as those of CdC and HNS. Also, don’t expect a UI that slavishly follows the Windows standard. This program began life as a DOS application, and has retained some of its old menu structure. It is not hard to learn, but it’s a little different. Frankly, it also looks a little old despite some fairly substantial updating in versions 4.0 and 5.0 (the current one).

Will Megastar’s modernization continue? Don’t look like it. The author turned marketing over to Willman-Bell not long before the current v5.0 came out some years back, and development has been very slow since. Scope control? You’ll be fine if you have a Celestron or a Meade or other popular go-to, but if you have something way off the beaten track, forget it. Megastar relies on built-in drivers rather than ASCOM, so it cannot support the huge number of computer-scopes CdC and HNS do. Despite these minor downchecks, if you are mainly a deep sky observer with a scope in the 12-inch and up range, you would be danged foolish not to give Megastar very serious consideration.

Earth Centered Univese

Like Megastar’s reams of data, but prefer something with a more standard interface and more planetarium-like bones? ECU is it. “Earth Centered Universe,” that is. Like Megastar, this one is busting at the seams with objects including the Hubble GSC and the whole PGC galaxy catalog. Unlike Megastar, however, ECU is equipped with fairly robust planetarium features. Like CdC and HNS, ECU uses ASCOM (defense contractor Unk is, yes, acronym obsessed) for telescope control, and can therefore interface to just about any scope you throw at it.

One thing I really liked about the program was the quality of ECU’s printed output. Many of today’s programs have near-type-set print quality, but this is the only one I have used that produces hardcopy every bit as good—or better looking than—the best print atlas. What puzzles me is why more folks don’t use Earth Centered Universe. Maybe because they haven’t heard of it. The author maintains a modest website, but as far as I know doesn’t run many (or any) ads in the astro-rags. The only way I learned about ECU was that David Levy once mentioned to me that this is what he uses, and I figgered that if he liked it a lesser mortal like me ort-to too.

The above does not mean it’s all gravy with ECU. If you don’t like “plain and simple” forget this one. It makes Cartes 3.0 look like, well, Stellarium. Also, if you decide there are features missing from the current version (5.0), don’t expect them to be added in the next release. It does not appear there will be a next release. The author appears to have stopped development. Which is a shame, since, with Megastar, ECU is my fav-o-rite DSO huntin’ app.


Unlike the programs we’ve been shooting the breeze about so far, TheSky is not the product of somebody’s garage. It is a professionally developed application done by a pro company, Software Bisque, and is the product of programming teams, not one dude working in his spare time. It shows. TheSky is beautiful, featuring a near photorealistic sky, but it is also useful. It has all the objects (or more) of a Megastar or an ECU, but with almost Stellarium-quality appearance. Despite its tremendous capabilities, TheSky 6 Professional (the top of the line of TheSky’s various levels/versions), like Stellarium, runs in surprisingly frisky fashion on older PCs. Are you a dyed-in-the-wool CCDer? TheSky integrates tightly with Bisque’s CCDsoft (and their other programs—like Tpoint—as well).

What brings many potential TheSky 6 Professional users up short is that ol’ demon the bank account. Yep, all this power is not cheap. Plan to fork over 250 shekels. On the other hand, the level “down” from “Professional,” “Serious Astronomer” does almost as much and is 150 bucks easier on the ol’ pocketbook. If there’s any bringdown here other than price, it’s simply that, like Megastar, TheSky uses built-in drivers rather than ASCOM. That is not as much of a problem here as it is with M-star, though, since TheSky supports many, many more scopes. There is also a way (somewhat convoluted) to make TheSky work with ASCOM—though it may not behave with some of the more unusual ASCOM drivers like EQMOD.

Starry Night

Want even purtier, and don’t wanna give up them zillions of objects? Want even more features, including things like the ability to download satellite weather maps for your observing site? Think “Starry Night.” And ‘specially Starry Night Pro Plus. Yep, it does tons of things. I’ve been using this one for over a year and it has capabilities I haven’t even begun to exploit—or even try—yet. The thing that sets it apart from every other astro-soft, though, is its "All Sky" display. Some of you may remember a planetarium program from a few years back, Desktop Universe, which used a mosaic of CCD images for its depiction of the heavens. That program was never a huge success, but part of it lives on. Its CCD sky was incorporated into Starry Night Pro Plus. Whether you are zoomed in or zoomed out, you are not looking at a cartoon. You are looking at honest-to-god images of the sky (usually with symbols, text, and other things superimposed).

So this should be the planetarium to end all other planetariums, right? It should be but it ain’t quite. I have enjoyed and benefitted from using Starry Night Pro Plus, but it has some quirks and weaknesses as well as strengths. With all these features and its virtual sky, SNPP is not something you will enjoy running on Aunt Lulu’s 566mhz Celeron. You’ll want the fastest PC with the fastest video card you can manage. Also, the program is intimately tied to Apple’s Quicktime. It needs this program to be present or it will not even run. Changes by Apple to Quicktime have been known to stop Starry Night in its tracks until a “fix” is released. This reliance on Quicktime may also be one of the reasons many Vista users have had trouble running SNPP under that operating system. Like TheSky, Starry Night Pro Plus is in the 250 buck neighborhood. Also like TheSky, however, you can buy lower levels that do almost as much for a lot less money (they do not, alas, feature All Sky). Ground truth? I sometimes cuss at SNPP, but I would not be without it. It simply does things nothing else does right now.

The Mac

“The Mac is back,” John McCain said recently. It turned out he wasn’t, but the Macintosh computer is. It is continuing to claim a larger and larger portion of the user base. So why haven’t I mentioned Mac programs? Simple: I don’t own a Macintosh. I do know that as Apple has increased its user share, more and more planetariums (and other astro programs) have begun to be targeted at the Mac mavens. Starry Night is and has been available for these computers. The new TheSky (“TheSky X”) will be out for Apple Real Soon Now (ahem). There is still the venerable Macintosh planetarium Voyager (recently updated). And even Cartes (the v3.0 beta) can now run on Macs.


A lot of amateurs wanna sit at their computer, click on objects on the planetarium screen, and have their go-to scopes slew to ‘em, so maybe a few words about the delicate art of scope interfacing are in order. What do you need and how do you do it? First of all, you will need to hook scope to laptop. Unless you have one of the late, lamented Meade RCX 400s, that will be via a serial cable. If your laptop does not have a “real” serial port, you will need to provide it with one via either a USB – Serial adapter cable or a PCMCIA serial card. The cable itself? Unless you are running EQMOD to a Synta mount, you cannot use a standard serial cable. You will need one appropriate for your Meade or Celestron or Acme StarDestroyer. Dealers will be happy to sell you one, or you can make one yourself (usually all you need is some multi-wire phone cable and one of them devilish little RJ connectors—check the web for plans).

One thing new go-to/laptop users get confused about is scope alignment. Do you do the go-to alignment with scope or computer? Unless you are doing the EQMOD thing, you will always align the scope “the old fashioned way” with the hand control. With scope aligned, fire up the laptop and all you should have to do to get going is select your scope from your program’s telescope menu (if your planetarium uses ASCOM, it will throw up ASCOM’s scope chooser window). After that, you can point and click your way to deep sky heaven. You may find that using a PC at the scope brings a lot of benefits that negate the aggravation of having to tote out one more piece of gear. Your planetarium will “add” hundreds of thousands of new objects to your go-to scope. Also, having that map displayed is a lot more informative than just staring at the dadgummed HC display: “Hmm…I wonder what else is in the neighborhood of NGC 253?”

So there you have it: my planetarium hit parade. Have I missed any great programs? I don’t think so, but I’d enjoy hearing about your faves, for shore. Is this all there is? Not hardly. In some ways I think the Planner programs, which I mentioned way back yonder at the start of this entry are even more useful to deep sky hounds than planetariums are. I think you will like ‘em too, and we will talk about ‘em “soon.”

I just recently got Voyager 4.5 for the PC. Have you used it? If so, how does it measure up?

With my limited experience, it seems to be quite impressive.

Thanks for any help on this question.

Terry Sandbek
Hi Terry:

I have not been able to try the Win Voyager yet. What have I heard? That they ran into some problems during its development, but it sounds like all those bugs have been squashed.

I know the Bisque Brothers are not sitting around while the competition is advancing. Look forward to a release of TheSky X pro in the near future.

When I lived in SoCal, almost every professional telescope I saw was running TheSky. Great telescope interfacing.
Just a nit - "Microsoft Virtual Telescope" is actually "World Wide Telescope" and it's put out by Microsoft Research.

The latest version (Equinox) includes 3-D solar system views/fly-throughs.

It also can control your scope via ASCOM, so I think it's quite a bit more functional than Google Sky. The tours are awesome, and in my mind make it superior to Stellarium as a teaching/learning tool - *if* you're connected to the internet.

Besides, the tours are awesome, and in the vernacular, it's just "purty." :)
HI David:

Good catch, thanks...fixed.

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