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Newtons Lichtgeschwindigkeit


Original-Zitat


Basiswissen


Isaac Newton beschreibt Beobachtungen an den Jupitermonden und schlussfolgerte daraus, dass Licht von der Sonne bis zur Erde etwa sieben bis acht Minuten benötigt (der Wert passt recht gut: es sind 8 Minuten und 20 Sekunden). Hier folgt das Original-Zitat aus Newtons Opticks aus dem Jahr 1704:

Original-Zitat


Light is propagated from luminous Bodies in time, and spends about seven or eight Minutes of an Hour in passing from the Sun to the Earth.

This was observed first by Roemer, and then by others, by means of the Eclipses of the Satellites of Jupiter. For these Eclipses, when the Earth is between the Sun and Jupiter, happen about seven or eight Minutes sooner than they ought to do by the Tables, and when the Earth is beyond the Sun they happen about seven or eight Minutes later than they ought to do; the reason being, that the Light of the Satellites has farther to go in the latter case than in the former by the Diameter of the Earth's Orbit. Some inequalities of time may arise from the Excentricities of the Orbs of the Satellites; but those cannot answer in all the Satellites, and at all times to the Position and Distance of the Earth from the Sun. The mean motions of Jupiter's Satellites is also swifter in his descent from his Aphelium to his Perihelium, than in his ascent in the other half of his Orb. But this inequality has no respect to the position of the Earth, and in the three interior Satellites is insensible, as I find by computation from the Theory of their Gravity.