243 Ida is an asteroid in the Koronis family of the main belt. It was
discovered on 29 September 1884 by Johann Palisa and named after a
nymph from Greek mythology. Later telescopic observations categorized
Ida as an S-type asteroid, the most populous type in the inner asteroid
belt. On 28 August 1993, Ida was visited by the spacecraft Galileo,
bound for Jupiter. It was the second asteroid to be visited by a
spacecraft and the first found to possess a satellite. Like all
main-belt asteroids, Ida's orbit lies between the planets Mars and
Jupiter. Its orbital period is 4.84 years, and its rotation period is
4.63 hours. Ida has an average diameter of 31.4 km (19.5 mi). It is
irregularly shaped and elongated, and apparently composed of two large
objects connected together in a shape reminiscent of a croissant. Its
surface is one of the most heavily cratered in the Solar System,
featuring a wide variety of crater sizes and ages. Ida's moon, Dactyl,
was discovered by mission member Ann Harch in images returned from
Galileo. It was named after creatures which inhabited Mount Ida in
Greek mythology. Data returned from the flyby pointed to S-type
asteroids as the source for the ordinary chondrite meteorites, the most
common type found on the Earth's surface.
Read the rest of this article:
Today's selected anniversaries:
Byzantine-Bulgarian Wars: Forces of the Byzantine Empire defeated
troops of the Bulgarian Empire at the Battle of Kleidion in the
Belasica Mountains near present-day Klyuch, Bulgaria.
Japan reluctantly signed the Treaty of Amity and Commerce, an Unequal
Treaty giving the United States various commercial and diplomatic
ENIAC , the world's first general-purpose electronic digital computer,
was turned on in its new home at the Ballistic Research Laboratory at
Aberdeen Proving Grounds, remaining in continuous operation until
October 2 1955.
U.S. President Dwight D. Eisenhower signed the National Aeronautics and
Space Act into law, establishing a new federal non-military space
agency known as NASA.
A worldwide television audience of over 700 million people watched
Charles, Prince of Wales, marry Diana Spencer at St Paul's Cathedral in
Wiktionary's word of the day:
1. A small European-style restaurant.
2. A small bar
Wikiquote quote of the day:
The Congress hereby declares that it is the policy of the United States
that activities in space should be devoted to peaceful purposes for the
benefit of all mankind.
Show replies by date