The sidereal messenger of Galileo Galilei : $b and a part of the preface to Kepler's Dioptrics containing the original account of Galileo's astronomical discoveries — John Shaqi
The sidereal messenger of Galileo Galilei : $b and a part of the preface to Kepler's Dioptrics containing the original account of Galileo's astronomical discoveriesGalilei, Galileo
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The sidereal messenger of Galileo Galilei : $b and a part of the preface to Kepler's Dioptrics containing the original account of Galileo's astronomical discoveries
Galilei, Galileo
Astronomy -- Early works to 1800; Jupiter (Planet) -- Satellites
Moreover, the great spots in the
Moon are seen to be more depressed than the brighter tracts; for in
the Moon, both when crescent and when waning, on the boundary between
the light and shadow, which projects in some places round the great
spots, the adjacent regions are always brighter, as I have noticed in
drawing my illustrations, and the edges of the spots referred to are
not only more depressed than the brighter parts, but are more even,
and are not broken by ridges or ruggednesses. But the brighter part
stands out most near the spots, so that both before the first quarter
and about the third quarter also, around a certain spot in the upper
part of the figure, that is, occupying the northern region of the Moon,
some vast prominences on the upper and lower sides of it rise to an
enormous elevation, as the illustrations show. This same spot before
the third quarter is seen to be walled round with boundaries of a
deeper shade, which just like very lofty mountain summits appear darker
on the side away from the Sun, and brighter on the side where they face
the Sun; but in the case of the cavities the opposite happens, for the
part of them away from the Sun appears brilliant, and that part which
lies nearer to the Sun dark and in shadow. After a time, when the
enlightened portion of the Moon’s surface has diminished in size, as
soon as the whole or nearly so of the spot already mentioned is covered
with shadow, the brighter ridges of the mountains mount high above the
shade. These two appearances are shown in the illustrations which are
given.
[8] Specimens of _frosted or crackled Venetian glass_ are to be
seen in the Slade Collection, British Museum, and fully justify
Galileo’s comparison.
[Sidenote: Description of a lunar crater, perhaps Tycho.][9]
[9] Webb, _Celestial Objects for Common Telescopes_, p. 104,
suggests this identification.
Public-domain text, read in full here on John Shaqi.
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