Good commercial programs don't die - they just get a new distributor. Such is the case with Commodore's SKY TRAVEL, owned now by Micro Illusions and distributed by Electronic Arts. This all-encompassing astronomy program first appeared in 1983 and has since become an instant classic.
SKY TRAVEL takes the often puzzling field of astronomy and brings it down to Earth, so to speak. Upon initial booting you are presented with a ground-level view of the night sky. All major stars and constellations appear as they should in real life, except that there are labels and constellation lines to aid you. All planets from Mercury to Pluto are represented by their Greek symbols while the sun and moon appear as round disks in the sky. Lunar phases are faithfully simulated.
Because this program is intended primarily for educational purposes and recreation, ease of use is extremely important. SKY TRAVEL excels at this, allowing even a novice user to effortlessly manipulate space and time.
All function key commands appear on-screen. Viewing options may be turned on and off at will, and in any combination. You have complete control of constellation lines, labels, planetary symbols and deep space objects.
Basically, SKY TRAVEL operates in four seperate modes which are accessable at any time. First there is the versatile SKY mode, which allows you to interact with the heavens. We will discuss this mode in detail further on.
Next is the SET mode. From here you set the time and date for your observations. Dates from 9999 B.C. to 9999 A.D. are permitted, although events taking place before 1752 are subject to calendar error. SKY TRAVEL takes into account the fact that the Earth is slowly wobbling on its axis, causing the 'North Star' to change every few thousand years (this is called PRECESSION).
The MAP mode is for setting your vantage point on Earth. A crosshair may be placed over any point on the Earth except the extreme north and south poles. Full latitude and longitude coordinates are displayed for fine-tuning.
Finally, the CHART mode creates a 'photo negative' star map complete with Right Ascension and Declination lines (which correspond to latitude and longitude on Earth). This may be printed out on any 1525-compatible printer.
Numerous useful features make SKY and CHART mode a pleasure to interact with. There is a tracing option that will lock onto a celestial object and track it as the Earth moves. The special FIND feature can immediately locate any planet or constellation you like and center it in the viewing window. The DEEP SPACE option displays galaxies, star clusters and nebulae.
There is even a SOUND option which, when invoked, causes your crosshair to turn into a starship and make a rocket noise when moved.
By far one of the most important features of SKY TRAVEL is the INFORM command, which can be invoked either from the keyboard or via joystick. Simply move your crosshair using the CRSR keys or joystick over any celestial object and press F7 or the fire button. The disk is accessed for a moment and suddenly, along the bottom of the screen, there appears a line of informational text that you can scroll back and forth.
Like in a planetarium, it is possible to watch special events occur - solar eclipses, for example - merely by setting time into motion. Pressing the plus key selects forward time travel anywhere from 1X (real time) to 64X (highly accelerated). The minus key can be used to slow down the progress of time. You may also go backwards at a rate of up to -64X.
When time is in motion, the program periodically makes calculations and updates the display accordingly. Because of the C64's limitations, selecting the 32X or 64X rate makes the computer spend most of its time feverishly calculating instead of sitting idle and waiting for input. This makes it very difficult to get a keystroke in edgewise. Often, the user must keep tapping away at the time control keys until everything comes to a stop.
The viewing angle may be reduced to provide a slightly higher degree of 'resolution.' The program starts out with a 72 degree viewing angle, which may be reduced in increments down to nine by pressing SHIFT-MINUS. The smallest viewing angle is excellent for resolving small details, like Andromeda's two satellite galaxies.
Although this all sounds very complicated, it really isn't. SKY TRAVEL operates almost intuitively, focusing your attention on the events on your monitor rather than on a page full of cryptic keyboard commands and special procedures. I found myself breezing through the program within minutes. As it turned out, most of my time was spent exploring and experimenting, not cursing and flailing my arms helplessly.
Naturally, I found myself itching to put SKY TRAVEL to the test. Thanks to some old back-issues of 'Sky & Telescope' - and an astronomy book entitled 'The New Solar System' - I was able to put SKY TRAVEL through its paces.
The first test I devised was one of the most interesting because it proved that the planet Neptune was actually discovered by Galileo Galilei 233 years before its official discovery. While observing Jupiter's satelites on December 28th, 1612, Galileo noted the appearence of a fixed star which somehow moved.
Enter SKY TRAVEL. After moving the MAP crosshair to Italy and leaping back in time to 1612, SKY TRAVEL clearly shows Neptune in very close proximity to Jupiter. Weeks later, SKY TRAVEL shows Neptune in a different part of the sky, just as Galileo had depicted.
The 'Sky & Telescope' issues high-lighted numerous solar and lunar eclipses, with enough time and locale information to zero-in on events practically in progress. The magazines also provided a varied assortment of lunar occultations (when the moon covers-up a planet or major star) and planetary conjunctions (when two or more planets are in line).
The program performed flawlessly and within reasonable levels of accuracy. In most cases, the events depicted on the screen - like a cresent moon slowly passing in front of a planet - closely resembled actual photographs.
SKY TRAVEL's 61 page manual may startle first time users for a moment, especially the way it makes the software packaging bulge omninously. It is actually one of the best manuals I've ever read. It is both clearly written and concise, without being long-winded or wordy. It begins in a friendly, conversational manner and maintains this tone throughout.
The many functions that SKY TRAVEL has to offer are painlessly explored with step by step instructions and examples. Some manuals have a tendency to go off on frequent tangents and try to explain too much. Not so with SKY TRAVEL.
Another flaw that plagues most user manuals is that they describe how to use the program and then just end at that. SKY TRAVEL goes far beyond this by offering documentation that you can actually learn from. Only a dozen pages are devoted to the operation of the program itself. The other 48 launch the reader into 'A Guided Tour of the Universe,' reminiscent of Carl Sagan's COSMOS series.
So much essential information is covered that the manual could concievably double as a mini-textbook. Unlike boring school textbooks, you are encouraged to boot-up SKY TRAVEL and become involved with the learning experience.
After seeing hundreds of dip-wit games come down the pike, it's nice to see a software package that realizes the full educational potential of the Commodore 64/128. Four stars for SKY TRAVEL.
