Young Folks' Library, Volume XI (of 20): Wonders of Earth, Sea and Sky
Science
Young Folks' Library, Volume XI (of 20): Wonders of Earth, Sea and Sky
Science -- Juvenile literature
hundred and eighty-four days.
Venus is thus Hesperus or Vesper, the evening star, when following the
sun as she passes from beyond him in superior conjunction to inferior
conjunction where she is nearest to the earth. As she again leaves him
behind in her course from this point to the opposite one of superior
conjunction, she appears in her second aspect as Phosphorus or
Lucifer, "the sun of morning," and herald of the day, shining as
"The fair star
That gems the glittering coronet of morn."
II.
THE PHASES OF VENUS.
But the changes in the aspect of Venus due to her varying positions in
her orbit are not confined to those which cause her to oscillate with
a pendulum movement eastward and westward from the sun. The discovery
that she undergoes phases exactly like those of the moon, followed
that of the existence of Jupiter's satellites as the second great
result achieved by the use of the telescope in the hands of Galileo.
The fact that the planets were intrinsically dark bodies revolving
round the sun, and reflecting its light, as he and Copernicus had
maintained, thus received a further ocular demonstration. The
Florentine astronomer describes in a letter to a friend how the
planet, after emerging from superior conjunction as a morning star,
gradually loses her rotundity on the side remote from the luminary,
changing first to a half sphere and then to a waning crescent; until,
after passing through the stage of absolute extinction when
intervening between us and the sun, she re-appears as a morning star,
and undergoes the same series of transformations in inverse order. The
revelation was indeed so novel and unexpected, that when the slight
deformation of the planet's shape was first detected by him, he did
not venture to announce it in plain terms but veiled it, according to
the prevailing fashion of the time, under a Latin anagram. His
celebrated sentence--
"Haec immatura a me jam frustra leguntur."
("Those incomplete observations are as yet read by me in vain.")
forms, by transposing the letters, the more definite statement,
"Cynthiæ figuras æmulatur Mater Amorum."
("The mother of the loves imitates the aspects of Diana.")
that is to say, Venus vies with the phases of the moon. The discovery
was an important one from its bearing on popular superstition ascribing
to the planets special influences on human affairs, for since they were
thus shown to transmit to us only borrowed light, belief in their
beneficent or malefic powers over man's destinies received a rude shock.
[Illustration: THE PHASES OP VENUS.]
Public-domain text, read in full here on John Shaqi.
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