The technical guides describe file formats, user-settable options, and algorithms used in the programs. Software and documentation are available via an anonymous ftp site on the Internet. The purpose of this exercise is to illustrate the measurement of the mass of a planet using Kepler's third law. Students make observations of Jupiter and its satellites at regular intervals over a period of several weeks, and, by graphing the separation of each moon from Jupiter versus time, they measure the period and radius of each satellite's orbit. This is sufficient information to derive the mass of Jupiter.
Students use the mouse cursor to identify the moons and to measure distances.
The purpose of this exercise is to illustrate the measurement of the rotation rate of a planet using the Doppler shift of a returning radar pulse. Students are given control of a simulated radar telescope. They point it toward Mercury and send off a narrow pulse of radio waves. The received echo, frequency versus intensity, is displayed for 5 time slices, which correspond to echoes from surface elements progressively further from the subradar point. By clicking the mouse cursor, students can measure the Doppler shift from the approachingand receding limbs of the planet, and from this determine rotational velocity of Mercury.