April 01, 2005

More about the Sun's Orbit, mentioned in the Qur'an

idbc wrote: "Nice try dunner, but the Sura implies that the moon and the sun have the same orbit. (#42)"

No, the sura makes no such implication. The sura states, "They float each in an orbit." (My emphasis.) Not, "they float each in the same orbit." I've tried to think about why you might have made such an erroneous original statement ("Why does the Quran say that the sun has an orbit, when we know it doesn't ?" (#38)). Even the ancients, as far back as Ptolemy (Claudius Ptolemaeus; 85-165 CE), knew that the heavenly bodies all travelled in separate orbits. My conclusion was that you must be taking the perspective of an observer who watches the sun, moon and planets as they traverse the zodiacal band, wherein most of those bodies (with the notable exception of Pluto, the comets and some asteroids) all appear to be moving within the same area of the sky. Even if we take this perspective, the earlier sentence in the sura remains true: "It is not for the sun to overtake the moon..." The sun, of course, can never "overtake" the moon in the sky. The moon moves too quickly in its apparent motion. When there's a solar eclipse, it is the moon that overtakes and then passes the sun, not the other way around.

"It should also be pointed out that is is NOT the 'SUN' that revolves around the a 'galactic center' but the entire solar system. (#43)"

Irrelevant. It is the sun's gravity that holds the solar system together. The sun orbits around the galactic center; the rest of the solar system is merely along for the ride.

"Also as I pointed out the sun does not 'orbit' the center of our galaxy. (#45)"

Never taken an astronomy class, huh? :) Well, here's some information for you:

"The sun is one of hundreds of billion of stars in our galaxy, the Milky Way. The galaxy is composed of gaseous interstellar medium, neutral or ionized, sometimes concentrated into dense gas clouds made up of atoms molecules, and dust. All of the matter -- gas, dust, and stars -- rotate around a central axis perpendicular to the galactic plane. The centrifugal force caused by the rotation balances out the gravitational force, which draw all the matter toward the center.

"The mass is located within the circle of the Sun's orbit through the galaxy is about 100 billion times the mass of the Sun. Because the Sun is about average in mass, astronomers have concluded that the galaxy contains about 100 billion stars within its disk.

"All stars in the galaxy rotate around a galactic center but not with the same period. Stars at the center have a shorter period than those farther out. The Sun is located in the outer part of the galaxy. The speed of the solar system due to the galactic rotation is about 220 km/s. The disk of stars in the Milky Way is about 100,000 light years across and the sun is located about 30,000 light years from the star's center. Based on a distance of 30,000 light years and a speed of 220 km/s, the Sun's orbit around the center of the Milky Way once every 225 million years. The period of time is called a cosmic year. The Sun has orbited the galaxy, more than 20 times during its 5 billion year lifetime. The motions of the period are studied by measuring the positions of lines in the galaxy spectra."

Source: Period of the Sun's Orbit around the Galaxy (Cosmic Year) (All italics mine.)

Understanding the Qur'an is a lot easier when you leave your preconceived notions behind.

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