For the amateur backyard astronomer, there are primarily two objects that are worthwhile for small and medium (2-8 inch) telescopes: the planets Jupiter and Saturn.
Jupiter is the fifth planet from the sun and is the largest in the Solar System. It is also one of the brightest planets in the sky, often being mistaken for Venus, but usually being visible for much longer due to its orbit. Visually, its color appears off white to the naked eye. Through a telescope of any size (and in binoculars) its four largest moons can be seen and tracked as they make their way around the planet. A small telescope will show two ruddy bands spanning the entire disk, one in the Northern Hemisphere and its counterpart in the Southern Hemisphere. In medium sized telescopes, the Great Red Spot can be glimpsed when atmospheric conditions permit, as well as shadows when moons cross in front of the planetary disk.
Saturn is the sixth planet from the sun and is second largest in the Solar System. Visually, it is a ruddy yellowish off-white color. Through a small telescope, it appears distinctly out of round. Larger telescopes allow a beautiful vista of the Saturnian ring system. The planetary disk is largely featureless, but the ring system can be seen in two or three groupings, separated by dark voids, the most prominent of which is called Cassini’s Division. Sometimes the largest of Saturn’s moons can be glimpsed as well.
Either of these two objects are perfect for the beginning amateur astronomer or deserve more detailed study by the more experienced. The beginner can time transits of the moons of Jupiter as well as transits of the Great Red Spot. As far as Saturn is concerned, the changing tilt of the rings over their 28 year period is always something of a marvel, especially around that time when the rings are seen edge-on and virtually disappear for the users of a small telescope. Especially intriguing is when Saturn appears inside of its rings as a crescent.
In all, many happy evenings can be spent exploring the two largest outer planets. All that is required is a 2 to 8 inch telescope, a clear sky, and the willingness to get outside and experience the sky the same way Galilieo and Kepler did centuries ago. Just remember to take a pad and a pencil to sketch what you see!
