Normally, a Saturn ring-plane crossing is a time of intense ground-based telescopic observation. However, at the time of the next crossing of Saturn's ring plane across the Earth (September 4,2009), Saturn will be at a poor position in Earth's sky, a scant 11° from the Sun. The following crossing of Saturn's ring plane through the Earth will be March 23, 2025, and the Earth and Saturn will again be on opposite sides of the Sun, although Saturn will be slightly farther from the Sun in Earth's sky than in 2009. Hence, no reasonably good Saturn ring-plane crossings will be observable from Earth until about 2040.
Following completion of the Cassini Mission at Saturn, there will be a body of ring and related data that will require decades to digest. As these data lead to conclusions, undoubtedly those conclusions will spawn countless theoretical and observational campaigns and perhaps even follow-on space missions. B. A. Smith  attempted in 1984 to predict the types of Earth-based observations that would contribute to improved knowledge of the known planetary ring systems (Neptune's ring system was still a matter of speculation). He accurately predicted that the Hubble Space Telescope would be an invaluable tool for such studies. His statement that "The principal problem with groundbased observations of... rings is the limited resolution imposed by the terrestrial atmosphere ...'' did not foresee the development of adaptive optics . Such optics now routinely achieve imaging resolutions comparable with and sometimes better than that of the orbiting Hubble Space Telescope. Learning from his experience, we will not attempt to outline in detail what can and cannot be observed about Saturn's rings from ground-based telescopes, nor what theoretical studies will be pursued, but it is certain that there will be many such observations and studies over the coming decades.
Stellar occupations viewed from Earth continue to be the primary means of studying the narrow rings of Uranus. Stellar occultations also provide useful data on the rings of Saturn and on the arc regions of the Adams ring of Neptune.
When the rings of Uranus were discovered in 1977, and when they were imaged by Voyager 2 in 1986, they were essentially concentric rings surrounding the planet. However, as Uranus continues in its orbit around the Sun, its ring system, like that of Saturn, is edge-on to the Sun twice each 84-year orbit. The next Uranus "equinox" occurs on December 7, 2007. Associated with that equinox, the Earth will cross the Uranus ring plane three times within a 10-month period, on May 2 and August 16, 2007, and on February 20, 2008 . These times will be very useful for observations of the tenuous dusty rings of Uranus, including the two recently discovered rings 2003U1R and 2003U2R.
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