By the 10th century, the university portion of the site, along with the library proper had been established in full.
The multiple courtyards and ornate interiors were decorated with lovely Arabesque calligraphy and tile work adorning the floors, walls, and ubiquitous arches, making it a beautiful architectural, as well as academic artifact.
The simulations show that the orbits of the inner planets (Mercury, Venus, Earth and Mars) have about a 99 percent chance of staying on their current, orderly paths for another 5 billion years, which is when the sun evolves into a red giant and swallows the inner solar system, incinerating the planets and thereby rendering orbital calculations somewhat beside the point.
Of the 2,501 scenarios covering the next 5 billion years that the Paris astronomers examined, 25 led to a disruption of Mercury's orbit sufficient to make it collide with Venus or the sun.It isn't every day that you read an astronomy paper that talks about the "grisly" details of changes in planets' orbits, triggering a tongue-in-cheek warning: "suffice it to say here that Earth does not fare well in the resulting interplanetary melee." But a pair of papers in today’s issue of Nature are not your everyday offerings.An embarrassing little secret of astronomy (dating to the days of Newton) is that the mathematical equations that describe the orbits of the planets have—how to put this? That is, the gravitational pull on a planet of everything but the sun is incalculable (literally; see the three-body problem.Even the beautiful courtyard fountains and mosaics have begun to fall apart.The library had been closed to the public for years when architect Aziza Chaouni was commissioned to restore the site.