From: Steve Koren Organization: The Amiga Online Review Column - ed. Jason L. Tibbitts III Phase-Of-Moon: the moon is waxing crescent (8% illuminated) Subject: REVIEW: Distant Suns 4.0 Keywords: utility, educational, astronomy Path: menudo.uh.edu Distribution: world Newsgroups: comp.sys.amiga.reviews Followup-To: comp.sys.amiga.applications Reply-To: Steve Koren This is a review of Distant Suns 4.0, an excellent astronomy program for Amiga computers. Distant Suns is powerful, expandable, and well worth the price. It has a few usability flaws but nothing which seriously detracts from the overall quality. I had previously owned 3.0, and took advantage of the VRLI offer to upgrade to version 4.0. This upgrade was $30. The list price if you are not upgrading is $99 US, although it is on sale from VRLI for $59.95 through October 1991. Distant Suns is available from VRLI (Virtual Reality Labs Inc). Virtual Reality Labs 2341 Ganador Court San Luis Obispo CA 93401-9826 Version 4.0 runs on any suitably equipped Amiga from a 500 to a 3000, under 1.3 or 2.0, and requires 1 mb or more of memory (the more the better). A hard disk is recommended. Some of the expansion data sets require larger machines. 68030/882 versions are available for machines with faster processors, and this makes the program more enjoyable due to the faster speed. Distant Suns: What Is It? ------------------------ Distant Suns is an astronomy program which, among other things, can act as a planetarium. It will also do many things a planetarium cannot do. The program started life under the name "Galileo", but there have been so many improvements since then that it can no longer be considered to be the same program. Distant Suns 4.0 (hereafter referred to as DS4) comes with a database of 4200 stars, many solar system objects, and 2000 "deep sky objects" such as nebula, globular clusters, etc. It can display these objects on the screen in the same manner as a planetarium. You see a view of the sky on the screen, covering a field of view which is adjustable from 1 degree to 180 degrees. Exactly what you see can be customized in many ways, but the default is to look at the stars and planets. Since at large angles there is distortion induced by mapping a spherical space onto a flat screen, you typically pick fields of view around 30 to 50 degrees. You can move your field of view around the sky by several methods. There is a small control window with arrow keys. You may click the mouse cursor on an area of sky to center in the screen. You may also search for any given object by name. (Ie, center the sky on Saturn, or M-78). In Planetarium mode, DS4 displays a location independent view of the sky. However, if you tell it your location on the earth and your time zone, it will save off this information in a file, and from there on it will be able to display the sky as it looks from your location and at the current time. (It gets the time from your computer's internal clock). In fact, the program is even able to store customized horizons which match the actual horizon where you live. You can now set the program to "real time" mode, which will cause the displayed sky to rotate in time with the sky overhead. You can also greatly speed up this rotation, anywhere from real time through 100 years of simulated time per 30 seconds of real time. DS4 can superimpose a large variety of data on the sky. For just a few examples, it can display planet names, constellation names and/or outlines, and even things like the magnitude, spectral class, or distance of every star displayed in the sky for which the data is known. Identifying Objects ------------------- DS4 has a neat feature whereby data may be displayed for almost any object in the sky. For example, I have an expansion data disk of 20000 stars which I bought with my program. I can click the mouse cursor on any one of these, and I can find out the name of the star (if it has one), the magnitude, the position, rise and set times, the spectral class, catalog number, whether it is a binary star, and if so the magnitude of its companion, their orbit period, the distance from Earth, and a whole host of other details. Even more information is provided for DSO (Deep Sky Objects) and planets. For example, I can click on M-31 and see not only the above information, but a paragraph describing the nebula, galaxy, or cluster, and a small image of it. I can then choose to view a full screen image of the object if I wish. This capability is only limited by hard disk space. All of the DSO have textual descriptions, often including information on what size of telescope is needed for viewing the object ("...in a 6 inch instrument one can make out the dark bands between the clouds, but an 8 inch scope is recommended to resolve more detail"). Many DSO have images as well. Off-Planet Views ---------------- Distant Suns can also generate views from any location within 800 AU of the sun. Further, it has the ability to generate standard IFF anim files. The first day I had the program I created an IFF anim which was taken from the viewpoint of Halley's Comet, covering the years 1984 to 1988. The resulting animation was spectacular. It is fascinating to watch planet motion from the viewpoint of Halley as it zooms around the sun and back out again. Many options are available, such as displaying the ecliptic plane, distances of planets above the ecliptic, etc. This ability is one of the most visually fascinating provided by the program. Any animations created with DS4 may be freely distributed. Animations with a fixed viewpoint can be a great tool for investigating solar system object interactions, and with a fixed viewpoint the resulting anim file is quite small. I generated a 300 frame high-res overscan anim file which took less than 250000 bytes of disk space. In a 2 meg animation, then, you could store about 2400 such frames. Of course, animations with a moving viewpoint are much larger. My Halley animation was 3 megabytes. Animations are generated directly to disk, so you do not need to have enough memory to store the animation and the program at once. User Expansion -------------- DS4 can be greatly expanded in many ways. First, you can currently purchase up to a 20000 star catalog for $20 US, with a 250000 star catalog coming soon from VRLI. You can also purchase other sets of DSO. The program comes with several thousand deep sky objects from the Messier and NGC catalogs, but you can purchase many more. VRLI also sells sets of image disks which contain images of these deep sky objects. The program can also be easily expanded by users. For a few examples, you can add your own object images to the database. You can also add custom objects, either within the solar system, or outside. Perhaps, for example, you are interested in tracking a small asteroid which the program doesn't know about. You can define this orbit to DS4, and thereafter, it will be able to display and track it for you. You may also add, for example, a custom catalog of pulsars from an outside source. VRLI claims in a recent newsletter that they are looking into CD ROMS which could store high res images for every DSO in the database. Personally, I am looking at the possibility of generating an animation of the Voyager I and II journeys from earth out of the solar system. Improvements from DS 3.0 ------------------------ DS4 is substantially different than 3.0. The general "look and feel" of the program is now much more professional. For example, you can now choose to run the program in high res/overscan mode in addition to medium resolution. The general layout is more logical, and "thoughtful" features have been added (such as the ability to use a dim red palette to avoid ruining night vision). DS4 supports external script control via AREXX. The possibility exists, as mentioned in the manual, for DS4 to control a real telescope through AREXX, given the appropriate telescope control hardware. You could set up a system where you could click the mouse cursor on a given nebula, and have DS move the telescope to that point in the sky. This is probably beyond the range of most hobbyist, but a small university or high school observatory could make good use of such a system. Thing which could use improvement --------------------------------- As always, DS4 isn't perfect. There are a few things I have wished could be improved: - The internal IFF viewer, while it works, isn't the best. For example, if a given object has multiple images, the must all be in the same resolution. It also won't let you scroll around a bigger bitmap than your screen. Instead of building this into the internal IFF viewer, it would be better to provide the ability to use an external picture viewer if one was available, with any command line options needed. Everyone has a favorite picture viewer, and its not practical to make the program try to do everything. - This is just a nit, but it would be nice if the application was multithreaded (as is, for example, NComm 1.92). Currently, if the "real time" screen rotation is on, the program will lock up for 5 seconds or so out of each 30 while it recomputes new star positions. This prevents you from doing other things such as interacting with various dialogs, etc. If different parts of the program ran as their own task, this problem would be prevented. However, this isn't a major problem; you can just turn off real time mode, or wait for 5 seconds. - The program seems to take quite a bit of CPU time even when it does not seem to be doing anything. (It seems to "use" about 50% of the CPU when idle). It would be nice if either the program took less CPU time when idle, or if there was some sort of pause feature which froze it. - DS4 takes various workbench "tooltype" options to configure itself upon invocation. I wish some of these were provided for shell users also. (They may very well be there, but I can't find them in the documentation). - Multiple horizon configurations would be nice. It appears as if this possibility was planned into the program and may appear in the future. This way, once could store configuration files for various observing locations, and be able to easily detect whether a given object was above the horizon from a given places. For example, I would like to store one configuration where the mountains to the west of my house obstruct low objects to the west, and another configuration taken far enough east that the obstructions are low. Conclusions ----------- DS4 is a great astronomy program, probably one of the best available for any personal computer. It has a great many features and abilities which I haven't touched on in this review. It is a good value for the price, and a worthwhile program for anyone interested in astronomy as a hobby. I could also be a fantastic tool for education; every student could have his or her own private planetarium to interact with. Astronomer hobbyists can use Distant Suns to view a date in the future, easily finding interesting objects to observe in a real telescope on that date, and even printing out that section of the sky to assist in finding the objects. The addition of expansion data makes the program more valuable, and this data is available from VRLI at a reasonable price. Rating: 9 on a scale of 1 (worst) to 10 (best). - steve (koren@hpmoria.fc.hp.com) 303-226-4985