Sirius is the brightest star in the night sky with a visual apparent
magnitude of −1.46, almost twice as bright as Canopus, the next
brightest star. The star has the Bayer designation Alpha Canis Majoris.
What the naked eye perceives as a single star is actually a binary star
system, consisting of a white main sequence star termed Sirius A, and a
faint white dwarf companion called Sirius B. At a distance of 2.6
parsecs (8.6 light years), the Sirius system is one of our near
neighbors. Sirius A is about twice as massive as the Sun and has an
absolute visual magnitude of 1.42. It is 25 times more luminous than
the Sun but has a significantly lower luminosity than other bright
stars such as Canopus or Rigel. The system is between 200 and 300
million years old. It was originally composed of two bright bluish
stars. The more massive of these, Sirius B, consumed its resources and
became a red giant before shedding its outer layers and collapsing into
its current state as a white dwarf around 120 million years ago. Sirius
is also known colloquially as the "Dog Star", reflecting its prominence
in its constellation, Canis Major. The heliacal rising of Sirius marked
the flooding of the Nile in Ancient Egypt and the 'Dog Days' of summer
for the Ancient Greeks, while to the Polynesians it marked winter and
was an important star for navigation around the Pacific Ocean.
Read the rest of this article:
<http://en.wikipedia.org/wiki/Sirius>
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Today's selected anniversaries:
1644:
The combined forces of the Scottish Covenanters and the English
Parliamentarians defeated the Royalists at the Battle of Marston Moor,
one of the decisive encounters of the English Civil War, near York.
<http://en.wikipedia.org/wiki/Battle_of_Marston_Moor>
1937:
Aviation pioneer Amelia Earhart and navigator Fred Noonan disappeared
over the Pacific Ocean during an attempt to make a circumnavigational
flight.
<http://en.wikipedia.org/wiki/Amelia_Earhart>
1964:
U.S. President Lyndon B. Johnson signed the Civil Rights Act into law ,
outlawing segregation in schools, at the workplace, and other
facilities that served the general public.
<http://en.wikipedia.org/wiki/Civil_Rights_Act_of_1964>
1976:
More than a year after the end of the Vietnam War, North and South
Vietnam officially united under communist rule to form the Socialist
Republic of Vietnam.
<http://en.wikipedia.org/wiki/Vietnam>
1997:
The Thai baht rapidly lost half of its value, marking the beginning of
the Asian Financial Crisis.
<http://en.wikipedia.org/wiki/1997_Asian_Financial_Crisis>
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Wiktionary's word of the day:
avatar (n):
1. (Hinduism) The incarnation of a deity, particularly Vishnu.
2. The physical embodiment of an idea or concept; a
personification.
3. A digital representation or handle of a person or being
<http://en.wiktionary.org/wiki/avatar>
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Wikiquote quote of the day:
Words do not express thoughts very well. They always become a little
different immediately they are expressed, a little distorted, a little
foolish. And yet it also pleases me and seems right that what is of
value and wisdom to one man seems nonsense to another.
--Hermann Hesse
<http://en.wikiquote.org/wiki/Hermann_Hesse>