Page:The sidereal messenger of Galileo Galilei.pdf/81

 the satellite on the east to Jupiter; from Jupiter to the satellite furthest to the west 7′. The two interior satellites on the western side were 0′ 40″ apart, and the satellite nearer to Jupiter was 1′ from the planet. The inner satellites were smaller than the outer ones, but they were situated all in the same straight line, along the ecliptic, except that the middle of the three western satellites was slightly to the south of it, but at the sixth hour of the night they appeared in this position (Fig. 20). The satellite on the east was very small, at a distance from Jupiter of 5′ as before; but the three satellites on the west were separated by equal distances from Jupiter and from each other; and the intervals were nearly 1′ 20″ each. The satellite nearest Jupiter appeared smaller than the other two on the same side, but they all appeared arranged exactly in the same straight line.

Jan. 23, at 0h. 40m. after sunset, the grouping of the satellites was nearly after this fashion (Fig. 21). There were three satellites with Jupiter in a straight line along the ecliptic, as they always have been; two were on the east of the planet, one on the west; the satellite furthest to the east was 7′ from the next one, and this satellite 2′ 40″ from Jupiter; Jupiter was 3′ 20″ from the satellite on the west; and they were all of nearly the same size. But at the fifth hour the