Find the middle of Line 2 then draw a perpendicular line down toward Line 1 until the lines meet. The point at which the lines 1 and 3 intersect is the SCP. From there just look straight down to the horizon and you've found south. Even though the Southern Cross moves around the sky during the year, the foot of the cross always points to the SCP, which is very handy if you've lost your compass or the sun's gone down.
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Skip to navigation Skip to content. This site is being redeveloped. For all the latest ABC Science content click here. As the Southern Cross dominates Crux constellation , it is often confused for the constellation itself, which contains more than five stars. The stars that form the cross asterism are just the brightest ones located in the constellation.
The cross-shaped pattern can easily be seen from the southern latitudes at any time of year. Observers in the tropical latitudes of the northern hemisphere can see it near the horizon in winter and spring, but only for a few hours every night.
Shining in the southern sky, the four bright stars portrayed in the left part of this image represent a useful orientation mark which helps identifying the south celestial pole.
Because of the rather distinctive asterism they form, these stars have been officially classified as the Crux constellation, or the Southern Cross. The ruddy object glowing in the upper part of the image owes its colour to the blaze of hydrogen gas.
Catalogued as IC , this emission nebula hosts a sparkling cluster of young stars. Two of the brightest stars that form the cross, Alpha Crucis and Beta Crucis, are among the brightest stars in the sky and easily visible from the southern hemisphere.
The stars Alpha, Beta and Delta Crucis are co-moving members of the Scorpius-Centaurus Association, a young association of stars in the constellations Scorpius and Centaurus that belong to the spectral class O and B, have common proper motion, and are believed to have formed inside the same giant molecular cloud.
It is the brightest star in the constellation Crux. It is really a multiple star system with a combined apparent magnitude of 0. Alpha Crucis is the southernmost first magnitude star, lying just a bit more to the south than the bright Alpha Centauri in Centaurus constellation.
Acrux lies at a distance of light years from Earth. It has an absolute magnitude of The two stars are separated by four seconds of arc. Alpha-1 Crucis has a visual magnitude of 1. Both components are hot class B stars on the verge of becoming class O. They belong to the spectral classes B0. Their surface temperatures are 28, and 26, K, and luminosities 25, and 16, times solar respectively.
The name Acrux is an abbreviation for the Bayer designation Alpha Crucis, which entered common use by the midth century. It was coined by the American cartographer Elijah Hinsdale Burritt around It is the second brightest star of the Southern Cross asterism. The star is about light years distant from the solar system. Beta Crucis has an apparent magnitude of 1. Mimosa is the 19th brightest star in the sky and Deneb , the 20th.
Mimosa is thought to be the hottest first magnitude star. The star is classified as a Beta Cephei variable with three different pulsation periods.
The stars orbit each other every five years. The Coalsack is one of the most prominent dark nebulae visible to the unaided eye. The Coalsack is located approximately light-years away from Earth in the southern part of the constellation of Crux the Southern Cross. This seemingly starless dark patch is actually an opaque interstellar dust cloud that obscures the light of the background Milky Way stars.
Dust grains in the cloud redden the starlight that reaches us by absorbing blue light preferentially, so that the red stars shimmering in the northern and darkest part of the Coalsack appear more crimson than they would in the absence of this dust.
The first European to see this remarkable object was probably the Spanish navigator and explorer Vincente Yanez Pinzon when he sailed to the South American coast in The Incas tell that the god Ataguchu, in a fit of temper, kicked the Milky Way and a fragment flew off, forming the Small Magellanic Cloud where it landed on the sky, and leaving the black mark of the Coalsack behind.
Beware of Inca gods in a bad mood! Another famous sight seen from southern latitudes — though it can creep into view in tropical northern latitudes — is the Southern Cross, or Crux. This cross-shaped constellation has assumed great significance in the cultures of the Southern Hemisphere, even as far back as prehistoric times.
The European Southern Observatory ESO has also acknowledged the significance of Crux as the foremost constellation of the southern skies, and has proudly incorporated the cross-shaped symbol into the ESO logo. The system is a relatively young one, with an estimated age of 8 to 11 million years. The primary component belongs to the spectral class B0.
The companion is believed to be a main sequence star belonging to the spectral class B2. A third star was discovered in , which may be a pre-main sequence star, and there are two other stars nearby which are believed to be optical companions, lying in the same line of sight but not physically associated with the Beta Crucis system.
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