In addition to Monday's rendezvous, Messenger is scheduled to pass Mercury again this October and in September 2009, using the pull of the planet's gravity to guide it into position to begin a planned year - long orbit of the planet in March 2011. (newscientist.com)
In 1915, Einstein explained that gravity arises because massive bodies warp space and time, or spacetime, causing free - falling objects to follow curved paths such as the arc of a thrown ball or the elliptical orbit of a planet around its sun. (sciencemag.org)
«The precisely timed orbits of these planets places strong constraints on how they could have formed,» Ford said. (keckobservatory.org)