The rings of Jupiter are a system of planetary rings around the planet Jupiter. The Jovian ring system was the third ring system to be discovered in the Solar System after those of Saturn and Uranus. It was first observed in 1979 by the Voyager 1 spaceprobe and thoroughly investigated in the 1990s by the Galileo orbiter. It has also been observed by the Hubble Space Telescope and from the ground for the past 25 years. Ground-based observations of the rings require the largest available telescopes. The Jovian ring system is faint and consists mainly of dust It comprises four main components: a thick inner torus of particles known as the 'halo ring'; a relatively bright, razor-thin 'main ring'; and two wide, thick and faint outer 'gossamer rings', named for the moons of whose material they are composed: Amalthea and Thebe. The main and halo rings consist of dust ejected by high-velocity impacts from the moons Metis, Adrastea and other unobserved parent bodies. High-resolution images obtained in February and March 2007 by the New Horizons spacecraft revealed a rich fine structure in the main ring. The age of the ring system is not known but it may have existed since the formation of Jupiter.

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_______________________________ Today's selected anniversaries:

1444: The Ottoman Empire under Sultan Murad II defeated the Polish and Hungarian armies under Władysław III of Poland and John Hunyadi at the Battle of Varna near Varna, Bulgaria in the final battle of the Crusade of Varna. (http://en.wikipedia.org/wiki/Battle_of_Varna)

1871: "Dr. Livingstone, I presume?" – Journalist and explorer Henry Morton Stanley located missing missionary and explorer David Livingstone in Ujiji, near Lake Tanganyika in present-day Tanzania. (http://en.wikipedia.org/wiki/Henry_Morton_Stanley)

1928: Hirohito was crowned the 124th Emperor of Japan. (http://en.wikipedia.org/wiki/Hirohito)

1969: The children's television series Sesame Street debuted on the National Educational Television network in the United States. (http://en.wikipedia.org/wiki/Sesame_Street)

1995: Playwright and environmental activist Ken Saro-Wiwa and eight others from the Movement for the Survival of the Ogoni People were executed by the Nigerian military government. (http://en.wikipedia.org/wiki/Ken_Saro-Wiwa)

_____________________ Wiktionary's Word of the day:

vouchsafe: To condescendingly grant a right, benefit, outcome, etc.; to deign to acknowledge. (http://en.wiktionary.org/wiki/vouchsafe)