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Thus, the Sun occupies 0.00001% (1 part in 10 7) of the volume of a sphere with a radius the size of Earth's orbit, whereas Earth's volume is roughly 1 millionth (10 −6) that of the Sun. Jupiter, the largest planet, is 5.2 AU from the Sun and has a radius of 71,000 km (0.00047 AU; 44,000 mi), whereas the most distant planet, Neptune, is 30 AU ...
[19] [20] Studies of the structure of the Kuiper belt and of anomalous materials within it suggest that the Sun formed within a cluster of between 1,000 and 10,000 stars with a diameter of between 6.5 and 19.5 light years and a collective mass of 3,000 M ☉. This cluster began to break apart between 135 million and 535 million years after ...
After small planetesimals—about 1 km in diameter—have formed by one way or another, runaway accretion begins. [20] It is called runaway because the mass growth rate is proportional to R 4 ~M 4/3, where R and M are the radius and mass of the growing body, respectively. [65] The specific (divided by mass) growth accelerates as the mass increases.
All remaining stars were regarded as "fixed" in the background. One important discovery made at different times in different places is that the bright planet sometimes seen near the sunrise (called Phosphorus by the Greeks) and the bright planet sometimes seen near the sunset (called Hesperus by the Greeks) were actually the same planet, Venus. [7]
This model posits that, 4.6 billion years ago, the Solar System was formed by the gravitational collapse of a giant molecular cloud spanning several light-years. Many stars, including the Sun, were formed within this collapsing cloud. The gas that formed the Solar System was slightly more massive than the Sun itself.
The Sun formed about 4.6 billion years ago from the collapse of part of a giant molecular cloud that consisted mostly of hydrogen and helium and that probably gave birth to many other stars. [125] This age is estimated using computer models of stellar evolution and through nucleocosmochronology. [13]
The Sun was found to be part of a galaxy made up of more than 10 10 stars (10 billion stars). The existence of other galaxies, one of the matters of the great debate , was settled by Edwin Hubble , who identified the Andromeda nebula as a different galaxy, and many others at large distances and receding, moving away from our galaxy.
The ancient Hebrews, like all the ancient peoples of the Near East, believed the sky was a solid dome with the Sun, Moon, planets and stars embedded in it. [4] In biblical cosmology, the firmament is the vast solid dome created by God during his creation of the world to divide the primal sea into upper and lower portions so that the dry land could appear.