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Crux: Difference between revisions
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Crux was visible to the Ancient Greeks; Ptolemy regarded it as part of the constellation Centaurus. It was entirely visible as far north as Britain in the fourth millennium BC. However, the precession of the equinoxes gradually lowered its stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. By AD 400, most of the constellation never rose above the horizon for Athenians. <ref>[http://en.wikipedia.org/wiki/Crux Crux]</ref> | Crux was visible to the Ancient Greeks; Ptolemy regarded it as part of the constellation Centaurus. It was entirely visible as far north as Britain in the fourth millennium BC. However, the precession of the equinoxes gradually lowered its stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. By AD 400, most of the constellation never rose above the horizon for Athenians. <ref>[http://en.wikipedia.org/wiki/Crux Crux]</ref> | ||
Like the Big Dipper ([[Ursa Major]] of the northern sky, the Southern Cross indicates the location of the pole and as such is often utilized by navigators. The longer bar of the Cross points almost exactly toward the south pole of the sky, which some aviators and navigators have named the "south polar pit" because, it is not marked by any bright star. According to the writings of Richard Hinckley Allen (1838-1908), an expert in stellar nomenclature, the Southern Cross was last seen on the horizon of Jerusalem around the time that Christ was crucified. But thanks to precession — an oscillating motion of the Earth's axis — the Cross ended up getting shifted out of view well to the south over the ensuing centuries. | |||
Immediately to the south and east of the Cross is a pear-shaped, inky spot, about as large as the Cross itself, that looks like a great black hole in the midst of the Milky Way. Legend holds that, when Sir John Herschel first saw this feature from the Cape of Good Hope in South Africa in 1835, he wrote his Aunt Caroline about this "hole in the sky.<ref>[http://www.space.com/29445-southern-cross-constellation-skywatching.html Southern Cross]</ref> | |||
Crux can be found on the national flags of Australia, New Zealand, Papua New Guinea, Samoa and Brazil. The New Zealand flag depicts only the four brightest stars of the Cross, while the banners of the other nations also include the faintest fifth star (known as Epsilon Crucis). | |||