System Requirements for the Interactive Sky Chart

Sky Chart
When you launch Sky & Telescope's Interactive Sky Chart applet in your Web browser, you get a naked-eye view of the sky on the left and an all-sky chart on the right, for any location and date you choose.
This applet has been developed using Java 1.1.0 library, Netscape's LiveConnect, ECMAScript (also known as Javascript), and related technologies.

Some browsers don't offer full support for these technologies in their default configurations. If you have trouble getting the Sky Chart to appear, or if you have trouble printing, please read the instructions below.

For help using the applet once it's launched in your Web browser, see Sky Chart Help. For tips on using the applet to explore the night sky from any location on Earth on any date from 1600 to 2400, see Fun with S&T's Interactive Sky Chart.

Before reading any further, make sure you know which operating system and Web browser you have. On a PC, our Sky Chart supports only Windows 98 or higher. On a Macintosh, our Sky Chart works on OS X and OS 9.1, but the functionality may vary depending on exactly which version and browser you're running.

If you use Internet Explorer on a PC, choose Help > About Internet Explorer from your browser's top menu. If you use Netscape Navigator, choose Help > About Navigator. In either case, the window that pops up will tell you which version of the browser you have.

On a Mac, here's how to find out which version of Mac OS you're running. Click on the Apple icon in the upper left corner of your screen. Then select "About this computer." In the pop-up screen, you should see something like "OS 9.1" (for Operating System version 9.1).

As explained on the next page, our Sky Chart is known to work on a Mac running OS X and Netscape 7; it may run with partial functionality in Internet Explorer and/or on other versions of Mac OS. If you have Netscape on your Mac, open the program and click the Apple icon in the upper left corner of your screen. Then select "About Communicator" to find out which version you're running.

Windows 98, ME, 2000, and XP

In the absence of any Java Virtual Machine, Windows XP users must download and install the JVM version recommended by Microsoft.

Note that you may need to activate Java manually once you download and install the JVM. It doesn't always configure itself to start automatically.


The Sky Chart applet has been tested extensively with Netscape 7 but may not work properly with earlier versions of Netscape.

Internet Explorer

This applet has been tested extensively with IE 6.0 and is known to work properly with IE 5.0 and 5.5 as well.

If you get an error message reporting that an ActiveX object is not secure, you need to adjust IE's security options. On your browser's menu bar select Tools > Internet Options...; click the Security tab; then click the "Custom Levels..." button. In the list of options for ActiveX controls and plug-ins, find "Script ActiveX controls marked safe for scripting" and make sure it is enabled.


The sky-chart applet appears to run properly in version 6.01 of the Opera browser under Windows 98 and under Windows ME with Sun's Java2 JRE version 1.3.1.

Macintosh OS X


You probably won't be able to set your observing location successfully unless you are using OS X 10.3 or later.

Other Browsers

It appears that under all versions of OS X, Internet Explorer doesn't support changing your observing location. We haven't tested Netscape or other browsers.

Macintosh OS 9.1


Currently, this applet is known to work only in Netscape 4.79 with the Macintosh Runtime for Java Plug-in, also known as the MRJ Plug-in. The MRJ Plug-in is a more stable and recent version of the Java environment. Installing this will generally make all applets run better in your browser. After installation, be sure to check the "Use Java Plug-In" box under the "Preferences...Advanced" menu.


The applet appears to work well in Netscape 4.75 on a PC running Red Hat Linux version 7.

Pop-Up Windows

If you've installed a "pop-up stopper" (or if your browser toolbar already includes one) to block advertisements that automatically open in new browser windows, you'll probably have to turn it off to use our Sky Chart, which needs to open in a new browser window.

3 thoughts on “System Requirements for the Interactive Sky Chart

  1. Richey-Scott

    Do you have a date for releasing the new/repaired skychart? My new version of Java absolutely throws the current one out. An email reply would be nice. Sorry to be such a pain.

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