`Sit, Jessica!', says young Lorenzo, addressing, not his dog, but Shylock's pretty daughter, of whom he finds himself enamoured. "Look how the floor of heaven," he goes on, "is thick inlaid with patens of bright gold."
Lorenzo was reflecting the common belief noted yesterday in Weather Eye that the stars were tiny luminous objects set permanently into the black, solid hemisphere of the celestial dome.
It appears thus because normally the stars seem motionless. But sometimes on a clear night you may see a bright object trace a moving path against this backdrop of the stars. If it streaks rapidly, and is gone almost before you have begun to notice it, the chances are it is a meteor - a "falling star"; if is it bigger and brighter than even the brightest of the stars and makes a droning sound, it may turn out to be an aircraft; but if it is comparable in brightness to one of the less brilliant stars and takes, say, 10 minutes or so to make its way across the sky, it is most likely to be an artificial satellite.
Although we rarely notice them, satellites can be observed on nearly any cloudless night. At this time of year, however, they are only to be seen during the few hours after sunset, or those immediately preceding sunrise; they are visible only when they are illuminated by the sun, and while at the same time, the observer on the ground is in the darkness. These conditions in turn are met only when the sun is below the observer's horizon, but not so far down that the satellites themselves are also in the Earth's shadow. Only near the summer solstice, can artificial satellites be seen in the middle of the night.
If you would like a little warning as to what satellites will be in your vicinity at any given time, you can get all the information you need from the website www.heavensabove.com. All you have to do is log on, select your location from the very comprehensive database of possibilities, and then wait for details of all artificial satellites worth watching for to be displayed. You can ask for current data, or for the information for any desired period in the future; in either case, for a long list of spacecraft and each one clearly named, you will be given the time and duration of their appearance, where in the sky to look for them, and their predicted brightness on the scale of "magnitude" astronomers use.