The Physical Appearance of the Planet

The disk of Jupiter presents a variety of features that can be observed by an amateur astronomer with modest equipment. Features both obvious and subtle await the eager observer. Indeed, Jupiter is often referred to as “the amateurs’ planet”, due in part to its enormous size and angular diameter that makes it easy to observe. The use of CCD cameras and web cams by many amateurs today is becoming more commonplace, with excellent images being obtained showing great detail. It is the physical appearance of the planet and ease of observation that fi rst attracts most of us. In this chapter we will deal with the physical structure, characteristics, and phenomenon that can be observed visually and by imaging; in other words, those things that anyone, including an amateur with a telescope, can see. Specifi cally, we will examine non-vertical structure in Jupiter’s clouds, winds, jet streams, and color. The observation of features on the surface of Jupiter, or rather in its cloud tops, and the observation of changes in the longitudinal and latitudinal positions of features, and the determination of the movement of features with regard to the speed of various currents and the appearance and reappearance of other phenomena, has been a mainstay of amateur observations since the beginning of recorded observations more than 150 years ago. While there is much to Jupiter amateurs cannot observe directly, these things we can see. Amateurs today continue this wonderful tradition of observational astronomy.