Formation and evolution of the Solar System have been forged from the remnants in less violent collisions. Moons around some asteroids currently can only be explained as consolidations of material flung away from the parent object without enough energy to entirely escape its gravity. Moons have come to exist around most planets and many other Solar System bodies. These natural satellites originated by one of three possible mechanisms: Jupiter and Saturn have several large moons, such as Io, Europa, Ganymede and Titan, which may have originated from discs around each giant planet in much the same way that the planets formed from the disc around the Sun.
Vulcan (hypothetical planet) circular orbits of Venus and Earth. Einstein's theory was empirically verified during the solar eclipse of May 29, 1919 by measuring the bending of sunlight. Astronomers generally quickly accepted that a large planet inside the orbit of Mercury could not exist, given the corrected equation of gravity. Observing a planet inside the orbit of Mercury is difficult, since the telescope must be pointed very close to the Sun, where the sky is only dark during a solar eclipse. Also, an error in pointing the telescope can result in damage for the optics, and injury to the observer if viewing directly.