Ursa Minor (Little Bear) is a constellation in the northern sky. It is colloquially known as the Little Dipper because its seven brightest stars appear to form the shape of a ladle (diagram pictured). It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. Polaris, its brightest star, is currently less than one degree away from the north celestial pole. Because this position stays nearly fixed as the Earth rotates, the star has traditionally been important for navigation, particularly by mariners. Polaris is a yellow-white supergiant and the brightest Cepheid variable star in the night sky, ranging in apparent magnitude from 1.97 to 2.00. Beta Ursae Minoris, also known as Kochab, is an aging star that has swollen and cooled to become an orange giant with an apparent magnitude of 2.08, only slightly fainter than Polaris. The constellation also contains an isolated neutron star—Calvera—and H1504+65, the hottest white dwarf yet discovered, with a surface temperature of 200,000 degrees Kelvin. Planets have been detected orbiting four of the constellation's stars, including Kochab.
Read more: https://en.wikipedia.org/wiki/Ursa_Minor
_______________________________ Today's selected anniversaries:
9:
The Western Han dynasty of China ended after the throne was usurped by Wang Mang, who founded the Xin Dynasty. https://en.wikipedia.org/wiki/Han_dynasty
236:
Pope Fabian, who is said to have been chosen by the Holy Spirit by having a dove land on his head, began his papacy. https://en.wikipedia.org/wiki/Pope_Fabian
1645:
William Laud, Archbishop of Canterbury and a fervent supporter of King Charles I, was beheaded in the midst of the English Civil War. https://en.wikipedia.org/wiki/William_Laud
1901:
The first great gusher of the Texas Oil Boom was discovered in the Spindletop oil field near Beaumont, Texas, US. https://en.wikipedia.org/wiki/Spindletop
1941:
Greco-Italian War: The Greek army captured the strategically important Klisura Pass in Albania. https://en.wikipedia.org/wiki/Capture_of_Klisura_Pass
1993:
The Braer Storm, the strongest extratropical cyclone ever recorded in the North Atlantic, reached its peak intensity. https://en.wikipedia.org/wiki/Braer_Storm_of_January_1993
_____________________________ Wiktionary's word of the day:
constraint: 1. Something that constrains; a restriction. 2. (mathematics) A condition that a solution to an optimization problem must satisfy. https://en.wiktionary.org/wiki/constraint
___________________________ Wikiquote quote of the day:
No obstacle has been so constant, or so difficult to overcome, as uncertainty and confusion touching the nature of true liberty. If hostile interests have wrought much injury, false ideas have wrought still more; and its advance is recorded in the increase of knowledge, as much as in the improvement of laws. --John Dalberg-Acton, 1st Baron Acton https://en.wikiquote.org/wiki/John_Dalberg-Acton,_1st_Baron_Acton