The System of Saturn

THE SYSTEM OF SATURN

observed [to be] more bright than the rest of Jupiter’s body, even though others assert they are darker; perhaps for these observers, the space between two brighter zones was taken for a single dark one. In the year 1656, we found these zones to be much further apart than in the following three years, as can be seen in the attached drawings. From this instability, we might reasonably conclude that, much like our own clouds, certain vapors occur in the ether Huygens refers to "ether" as the substance filling space, but here he means the atmosphere surrounding the planet. near Jupiter, arising more frequently and thickly in some climates than in others.

On Mars, too, I detected a single belt of this kind in 1656; it was quite wide and darkened the middle part of the disk, as the attached figure demonstrates. Furthermore, I have seen the disk of this planet partially missing This refers to the "gibbous" phase of Mars, where it appears not quite circular as seen from Earth. at times, and on Venus, I have seen all the phases just like those of the Moon. But others have noted these things even with smaller telescopes.

As for the diameters of the fixed stars original: Fixarū [stellarum]. In this era, "fixed stars" were distinguished from "wandering stars" or planets., even the most brilliant ones, I could never see any width to them. Instead, they appeared only as the tiniest point whenever I used glass lightly stained with soot to remove the rays Early telescopes suffered from glare and optical aberrations that made stars look like large, fuzzy disks. Huygens used "smoked glass" as a primitive neutral density filter to see the true, point-like nature of stars.. However, following the advice of Hevelius Johannes Hevelius (1611–1687) was a prominent Polish astronomer., which appears in his excellent work Selenographia Published in 1647, this was the first atlas of the Moon., I tried covering the outer lens so that only a small opening remained. By doing this, I saw the stars display some size; I judge this size, therefore, not to belong to the stars themselves, but to arise from a deception of sight. For our method of looking at stars through the smoke with which the lens nearest the eye is tinted is certain and free from any suspicion of error; we are also accustomed to viewing the planets when they radiate too much light, and even the Sun itself, in this way. By excluding most of the light with a small hole, I believe the rays surrounding the stars are not entirely removed, but are instead forced into a smaller and quite perfectly rounded circle, which deceives the unwary into taking it for the body of the star itself.

A rectangular illustration on a dark, crosshatched background features three circular planetary disks. At the top left, a disk marked with the astrological symbol for Jupiter (♃) shows four horizontal dark bands. At the top right, another disk also marked with the Jupiter symbol (♃) displays two broad, prominent horizontal dark bands across its center. Below these, a smaller circular disk marked with the symbol for Mars (♂) shows a concentration of fine horizontal lines across its equatorial region, representing early observations of planetary surface or atmospheric features.