Classic Computer Magazine Archive COMPUTE! ISSUE 92 / JANUARY 1988 / PAGE 38

Galileo For The Amiga

Ervin Bobo

Requirements: Amiga with a minimum of 512K.

Astronomy programs exist for every leading personal computer, but it is only now, with a combination of Galileo and the Amiga, that one of the major obstacles to a realistic astronomical display has been overcome. Previously, the limitation of computer graphics made it necessary to show every star, planet, and deep space object at the same level of brightness. While this was a workable situation, it required that the magnitudes of heavenly bodies either had to be stated in text or ignored. This may seem a small matter— but it is not, and your first look at the working screen of Galileo, with nine distinct levels of brightness, should be enough to make you catch your breath.

Following that, you'll have other opportunities for surprise, and perhaps at least one for dismay.

Star Light, Star Bright

Once booted, Galileo presents you with a picture of the night sky and, at the left of the screen, a control panel. Activated by mouse-clicks, this panel allows you to scroll the screen in four directions and to zoom in on portions of the sky. In addition, this panel displays the coordinates of the object currently under the onscreen crosshairs, as well as indicating whether you are in Planetarium, Local, or Flashcard mode.

Planetarium mode displays the stars in absolute form, with the Pole Star at screen center. Local mode shows you the heavens as they would appear from your selected location (as well as selected date and time). Once you choose a location, that information can be saved to your working disk, and this will become the default setting whenever you select a Local view. Then, by using either Quickview or the scrolling arrows, you can select a direction for viewing that will be the same as that obtained when standing on your back porch, or anywhere else you may choose.

Flashcard has nothing to do with viewpoint. Instead, it presents a constellation for your identification. You may click on the left mouse button to see whether your guess is correct. As its name implies, Flashcard is a learning tool.

Galileo takes advantage of the stunning graphics capabilities of the Amiga, and displays a realistic skyscape with nine different levels of brightness.

Any Time, Any Place

Via pulldown menus, you can enter the date and time for which you're interested. Galileo is said to have reasonable accuracy for any date 400 years in the past or future. Beyond those points, accuracy will diminish because of certain movement factors not considered by the program.

Next, select the location from which you wish to view the sky. An appendix provides latitude and longitude for over a hundred major cities around the globe, thus making it possible for you to teleport to Buenos Aires if that happens to be the best place from which to observe a solar eclipse or a planetary conjunction.

Lighting, either Bright or Normal, can be selected, and this changes the intensity of the display without altering the relative brightness of the stars. (It is suggested you use Galileo in a dim or darkened room to obtain the fullest effect, and to avoid distracting reflections on your monitor screen.)

You may also select the amount of Skylight (though ground scatter is the more familiar term). With this, you duplicate the ambient light of cities, towns or country. Switching from Country to City light, with the consequent disappearance of dimmer stars, shows you just how much city dwellers miss. On the other hand, it is probably easier for them to identify major objects and constellations without the crowded background of other stars.

Magnification Factors

The Telescope option opens a magnifying window on the screen. Use your mouse pointer to select an object in which you are interested, and an enlarged view of it will appear in the window. Such views are relative to the size and distance of the object—while the moon almost fills the window, Saturn is barely large enough for you to distinguish its rings. Since even highly enlarged stars are still points of light, the telescope is useful only for the objects within our solar system.

For deep-sky objects, another form of identification is provided: You may choose to display Messier Objects, 110 of which are identified by the M number. Alternatively, NGC (New General Catalog) objects are represented by colored dots—though if your field of view is less than 30 degrees, there will be room for their labels to be displayed.

Still another identification system is invoked by choosing the Brightstar option from the menus. When this is done, 35 of the brightest stars will be identified.

In addition to these, constellation lines and names, as well as planetary names, may be toggled on or off from the proper menu. During such toggling, or any other changes made such as direction of view, time, and so on, there will be a wait while the screen redraws itself. While this may seem tedious, bear in mind the complexity of calculations your computer must consider in order to effect a change and still maintain accuracy.

Another unique feature from the Extras pull-down menu is the What's Up? option. By selecting this, you'll be told in graphic form what planets are visible for this particular day and time, for the time of sunrise and of sunset, for the different phases of the moon, and for the date of the next meteor shower.

Although meteor showers are not displayed by Galileo, solar eclipses and planetary eclipses are included. Unfortunately, the documentation gives you the times and coordinates for only one of each, so you'll have to refer to your astronomy books and magazines for others.

The Size Of The Universe

It's possible there may be some lamentations among the more serious students or professionals in astronomy: only 35 bright stars identified, only 110 Messier Objects, only 340 NGC objects. Granted that those are but small portions of what is really out there, we should keep in mind that we are dealing with a whole universe, and that all of it could simply not be stuffed into a computer of 512K. What is here is choice—and it is well worth your while.

Documentation is very good, serving as a primer on many aspects of astronomy, with brief discussions of planetary conjunctions, an overview of meteor showers and deep sky objects, and much more.

For me, the one serious deficiency in Galileo is that it does not have the ability to print what you see on your screen. Nor will it run in conjunction with any of the screen dump programs in my library. There are times when hard copy would fill a great need: A beginning student could make a print out of the sky with constellation lines in place and take it outside with him that night as an aid to identification.

Despite that one shortcoming, I think you'll find Galileo to be a highly valuable tool.

Infinity Software
1144 65th St., Ste. C
Emeryville, CA 94608

(An upgrade, expected in late 1987, will be priced at $69.95.)