SkyGazer FAQ

What are the main differences between Voyager and SkyGazer?

Think of SkyGazer as the "Lite" or introductory version of our software, and Voyager as the "Pro" version:

• SkyGazer has a database that can show you everything you can see with your eyeballs, or a through a pair of binoculars/a small telescope. Voyager's database, on the other hand, contains more objects than most large backyard telescopes can see.
• Voyager can control a computerized telescope; SkyGazer cannot.
• Voyager is designed to predict the positions of the Sun, Moon, planets, asteroids, comets, and spacecraft with the highest possible precision; SkyGazer gives enough precision for casual, naked eye observation.
• Voyager's interface contains a complete set of options for configuring nearly every aspect of how the program computes and displays celestial phenomena; SkyGazer's user interface is simpler, and contains fewer options.
• On the other hand, SkyGazer contains some educational features - such as our illustrated SkyGuide introduction to basic astronomical concepts, the planets, and the constellations - not found in Voyager.

How do Voyager and SkyGazer differ from other astronomy programs that are out there?

There is a lot of astronomy software available today! Much of it is very good, and some of it is even available for free. However, you'll find that very few programs - commercial or otherwise - can perform the range of simulations with the same ease-of-use that Voyager and SkyGazer provide. For example:

• One leading commercial astronomy program can only show you the night sky as seen from the Earth. The most popular open-source program can only show you the sky as seen from locations other than Earth. We can take you to any place on Earth, in the Solar System, or thousands of light years beyond into interstellar space.
• Many commercial astronomy programs require high-end graphics hardware to function reliably; ours does not.
• Voyager's database and computing engine was written by a MIT planetary science graduate for research-level accuracy; and while we can't vouch for anyone else, we can guarantee that our software has been through years of rigorous testing.
• Our user interface is the result of many years of experience in astronomy education, and is among the best in the business.

But don't just take our word for it - download our free demo version, and try it yourself!

I'm trying to install SkyGazer on Windows XP/Vista, and the installer gives me an error message that says: "Unable to Save File ... The System cannot find the path specified". Help!

You need to run the SkyGazer installer from an account with administrative privileges. Log off Windows and log on again, into an account with administrative priveleges. If you don't own the computer (for example, a computer in a school lab), you'll need to contact your system administrator or other friendly-neighborhood IT staff to get you administrative priveleges on the computer. Or find a hacker who can crack the computer's administrative password for you. :)

I changed my location, but every time the program starts up, it says I am located in San Francisco. How do I make SkyGazer save my location?

After changing your location (or, for that matter, any other setting you wish to have the program start up with by default), use the Save Startup Settings command, in the File menu. This will overwrite the default settings file, and ensure that the program starts up with your new settings every time.

I want to show the entire sky as a "ball", similar to the monthly star maps printed in Sky & Telescope or Astronomy magazine, but the edges are cut off at the sides of the window. How do I show the full sky in a SkyGazer window?

First, you need to use the Orthographic or Stereographic projection. Set the field of view to 180 degrees, then "look straight up" by centering the zenith. Finally, resize the chart window so that the window itself is square. To print a sky chart like this, make sure you're printing in "portrait" mode, not "landscape" mode, so that the printed page is taller than it is wide.

I'm running SkyGazer on Mac OS X, and I can't change the time step (in the Time Panel) or the field of view (using the menu in the lower left corner of the chart window). I click on the time/zoom menu button but no menu appears. Why?

Check to see if your display is running in 16-bit color (i.e. thousands of colors). If so, switch it to 32-bit color (i.e. millions of colors). That should solve the problem. This appears to be a bug in Mac OS X, which we've reported to Apple on several occasions, but as of this writing (OS X 10.5.2) still appears to be present.

I'm using SkyGazer to predict the position of an asteroid, comet, or spacecraft, but the position is significantly different from what I've found in another source (like a magazine, or an on-line ephemeris). What's the problem?

This is almost certainly the result of using outdated orbital elements for the asteroid, comet, or spacecraft in question.

Because of the gravitational perturbations of the other planets, the orbit of any object in the solar system is always changing. Therefore, a single set of orbital elements will gradually become less accurate over time. However, most asteroid and comet orbits change slowly enough that predictions based on a single orbit should be good to about an arcminute for several years, which ought to be sufficient for locating them in the sky.

Artificial satellite orbits tend to decay rather quickly, so it is important to use up-to-date orbits. As a rule of thumb, satellite orbital elements should be considered "out of date" and not trustworthy for predictions after 30 days.

The ability to import and update asteroid/comet/spacecraft orbits is currently limited to Voyager. SkyGazer ships with a fixed set of orbits for these objects that cannot be updated. If you want to use our software for serious asteroid/comet/spacecraft observation, we recommend that you purchase Voyager rather than SkyGazer.

Can SkyGazer show me the Moon/Mars landing sites? Can your software show me the night sky from a planet other than Earth?

No. But that's coming soon.

Can SkyGazer control my telescope?

No. SkyGazer is designed purely for eyeball or binocular observing.

Do you have an astronomy textbook that can be used along with SkyGazer in the classroom?

SkyGazer is bundled with Benjamin Cummings' excellent introductory college level astronomy textbook, "The Cosmic Perspective". You can purchase a copy of this textbook on-line from Benjamin Cummings or Amazon.com.