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.
Read the rest of this article:
http://en.wikipedia.org/wiki/Rings_of_Jupiter
_______________________________
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)