Mars24 is a Java program which displays a Mars sunclock, a graphical representation of the planet Mars showing its current sun- and nightsides, along with a numerical readout of the time in 24-hour format. Other displays include a plot showing the relative orbital positions of Mars and Earth and a diagram showing the solar angle for a given location on Mars. Mars24 runs on many different types of computers, including Windows, Mac OS X, Linux, and more, but it requires Java 1.5 or better be installed on the computer. The associated MER Spirit/Opportunity Clock Applet requires only Java 1.1.8 and is compatible with many older web browsers, but it does not include Mars Phoenix timing or the sunclock or other graphic displays of Mars24.