Braille [key], in astronomy, a small asteroid notable because it has the same atypical geologic composition as the larger asteroid Vesta. In 1999 the space probe Deep Space 1 passed within 16 mi (26 km) of Braille's surface, the closest flyby ever of an asteroid. Braille measures only 1.3 mi (2.1 km) by 0.6 mi (1 km). Its orbit is highly elliptical; its periapsis, or closest point to the sun, being midway between earth and Mars, and its apoapsis, or furthest point from the sun, is more than three times further from the sun than the earth is. In addition, much of Braille's orbit, and much of it is a considerable distance above or below the ecliptic, the plane in which the planets circle the sun. Because of its orbit and geologic composition, it has been suggested that Braille was torn from Vesta, which has a huge crater, as the result of Vesta's collision with another celestial body.
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