Celestial Crow (CORVUS) and Cross Standing Out in Night Sky

Celestial Crow and Cross Standing Out in Night Sky..
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Corvus coordinates: 12h 00m 00s, -20degrees 00' 00''

A cosmic crow is making an appearance in the southern night sky this week and can be spotted about a third of the way up from the horizon at around 10 p.m. local time. Weather permitting, the sight will give skywatchers a glimpse of the famous Sickle of Leo, and probably the most striking star pattern in the spring southern sky for those living at mid-northern latitudes: Corvus, the Crow.

This celestial bird appears as a small, moderately bright quadrilateral-shaped pattern of stars – like a triangle whose top has been removed by a slanting cut. Add a fainter adjoining star, known as Alchiba, and the pattern resembles the battened mainsail of a Chinese junk.

Corvus can also be used to positively identify the bluish first-magnitude star Spica, in Virgo.

Just follow the direction of Corvus' slanting top to the east (to the left) and you will soon arrive at Spica. It almost appears in the sky as if Corvus were poised, waiting for a chance to grab at Spica, which represents a spike of wheat held in Virgo's hands.

In a way, this makes some sense, since crows are omnivores and will eat almost anything. They are also extremely smart. They will cautiously hop near whatever attracts their attention, then leap in and grab it.

Corvus is supposed to represent the unfaithful raven of the god Apollo. The bird was sent out with a cup for some water, but instead loitered at a fig tree until the fruit became ripe. He then returned to Apollo without the cup, but with a water snake in his claws, alleging the snake to be the cause of his delay.

As punishment, the angry Apollo changed Corvus from silvery-white to the black color that all crows and ravens bear to this very day. In addition, Corvus was forever fixed in the sky along with the Cup (Crater) and the Snake (Hydra), doomed to everlasting thirst by the guardianship of the Hydra over the Cup and its contents.

The Southern Cross beckons

Interestingly, when the four-sided Corvus has reached its highest point in its course across the sky, it stands directly above Crux, the famous Southern Cross, which is also attaining its highest point above the South Pole of the sky.

But unfortunately, even at its highest, the Cross remains out of sight below the horizon nearly everywhere in the United States. To see Crux, one must go at least as far south as latitude 25 degrees north. That means heading to the Florida Keys in the continental United States, where you'll see it now just lifting fully above the southern horizon.

A slightly better view is afforded to those living in Hawaii, where the Cross appears a few degrees higher.

But for those who live in the Southern Hemisphere, the Cross is by far the most well-known constellation, even prominently displayed on the national flags of Australia, New Zealand, Papua New Guinea, Samoa and Brazil. Those south of the equator (where it is now late autumn), need only cast a glance toward the south where they'll see the distinctive shape of the Cross hanging well up in the sky.

To some, it looks more like a kite, though the Cross is clearly outlined by four bright stars, two of which, Acrux and Becrux are of the first magnitude.

From top to bottom, Crux measures just 6-degrees – only a little taller than the distance between the Pointer stars of the Big Dipper. In fact, the Southern Cross is the smallest (in area) of all the constellations. Like the Big Dipper 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, unfortunately, it is not marked by any bright star.

Who saw it first?

It is thought that Amerigo Vespucci was the first of the European voyagers to see the "Four Stars," as he called them, while on his third voyage in 1501. But actually, Crux was plainly visible everywhere in the United States some 5,000-years ago, as well as in ancient Greece and Babylonia.

According to Richard Hinckley Allen (1838-1908), an expert in stellar nomenclature, the Southern Cross was last seen on the horizon of Jerusalem about the time that Christ was crucified. But thanks to precession – an oscillating motion of the Earth's axis – over the centuries, the Cross ultimately ended up getting shifted out of view well to the south.

Immediately to the south and east of the Cross is a pear-shaped, inky spot, about as large as the Cross itself, looking like a great black hole in the midst of the Milky Way.

When Sir John Herschel first saw it from the Cape of Good Hope, South Africa in 1835, it is said that he wrote his aunt, Caroline about this "hole in the sky."

Indeed, few stars are seen within this hole and it soon became popularly known as the "Coalsack" which initially was thought to be some sort of window into outer space. Today we know that the celebrated Coalsack is really a great cloud of gas and dust that absorbs the light of the stars that must lie beyond it.

So it is that the four stars that outlines the figure of a wily crow, also reveals the position of another four-star pattern whose name is known to almost everyone though invisible to many of us.

Last Edited by _Anon_ on 05/21/2010 09:37 AM