And it IS a spaceship.

UFO widely seen in Middle East skies, linked to Russian missile test has an update from James Oberg, explaining that the spiral does not indicate a failed launch, but is a deliberate feature needed for the trajectory the Russians wanted.

Earth-Companion Asteroid Discovered in Horseshoe-Shaped Orbit, referencing A long-lived horseshoe companion to the Earth.
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Alessandra Celletti and Ettore Perozzi, Celestial Mechanics: The Waltz of the Planets. This is a semi-popular look at one of my old and persistent interests. Very little math, but a lot of graphs and terminology. It includes the traditional subjects, e.g. tidal forces, the discovery of Neptune, Delaunay's lunar theory, and the stability of the ( Read more... )