#Jupiter hell distance explanation full

This effect was not detected with even the best astronomical instruments during the time of the ancient Greeks. If Castor and Pollux are fixed on the celestial sphere, then the distance CP between them is a fixed length.īecause they are fixed objects, the distance CP in this case appears largest when closest, and smallest when most distant. If one views the heliocentric model from the north ecliptic pole in Figure 1 we see the sun, Earth (E) in several positions in its orbit, Castor (C), and Pollux (P) on the celestial sphere. In heliocentric theory, the ecliptic is the projection of Earth ’s orbit onto the sky. Those most likely to show the effect of this yearly motion are those in Gemini, especially its brightest stars: Castor and Pollux, which are about 4.56 ° apart and close to the ecliptic, the sun ’s yearly path among the stars. Aristarchus concluded that the sun was several times larger than Earth, and thought it reasonable that the smaller Earth revolved around the larger sun.īecause the stars are all located on an enormous celestial sphere (the entire sky) centered on the sun, Earth ’s yearly motion around the sun is reflected in the stars. From this value he determined the sun ’s distance and the relative sizes of Earth, the moon (about 1/4 that of Earth), and the sun. The smaller the difference between the intervals, the more distant the sun.

#Jupiter hell distance explanation full

Observing the new moon to the first quarter and the first quarter to full moon, then using geometry and several assumptions, Aristarchus used the time-interval differences to calculate the sun ’s distance from Earth. Over 200 years later Aristarchus of Samos (310-230 BC) attempted to measure the sun ’s distance from Earth in Earth-moon distance units by measuring lunar intervals. This was seen as more plausible than the heliocentric theory because to a casual observer, all celestial bodies seem to move around a motionless Earth at the center of the universe. Only a round body can always cast such a shadow.ĭespite this discovery, the prevailing theory at that time was that of a geocentric (Earth-centered) universe, in which all celestial bodies were believed torevolve around Earth. By the sixth century BC they had deduced that Earth is round (nearly spherical) from observations that during lunar eclipses Earth ’s shadow on the moon is always a circle of about the same radius wherever the moon is on the sky. The first evidence of the theory is found in the writings of ancient Greek philosopher-scientists. Everything else (planets and their satellites, asteroids, comets, etc.) revolves around it. The heliocentric theory argues that the sun is the central body of the solar system and perhaps of the universe. Copernican revival of the heliocentric theory