Astro Bob A look at celestial happenings in the Northland and beyond Bob King View my profile Click here to view previous posts or additional resources

A wedding band for lovebirds and a sinkhole for the ages

The constellation Fornax the Chemical Furnace depicted by Johann Bode in his Uranographia celestial atlas of 1801. The constellation was originally introduced by Frenchman Nicolas Louis de Lacaille in the mid-1700s.

The ancient constellation makers put a lot of animals and heroes in the sky but very few inanimate objects. Yesterday we looked at Libra the Scales which may have been resurrected by the Romans from ancient Babylon. In addition there are Ara the Altar, Crater the Cup, Triangulum the Triangle, Corona Borealis the Northern Crown, Corona Australis the Southern Crown, Sagitta the Arrow and the ancient ship Argo Navis, now broken into three separate constellations. That makes a total of eight inanimates familiar to ancient Mediterranean sky watchers. Celestial cartographers in the 17th and 18th centuries added 17 more including such wonders as Fornax the Furnace and Pictor the Painter's Easel.

Corona Borealis lies a little more than one outstretched fist to the left of Arcturus high in the southern sky at nightfall. Created with Stellarium

Pity no one created a wedding ring. I can't think of a more appropriate and symbolic image to place in the sky. Stars' lifetimes span billions of years just as a marriage ideally spans the remainder of our lives till death do us part. That's why I'm going to ask you to picture Corona Borealis, now conveniently located in the early evening sky, as a stand-in for a wedding band. Corona represents the crown worn by princess Ariadne of Greek mythology to her wedding, and while it serves that function admirably, its semi-circular form makes an even better ring. Its brightest star, Gemma (JEH-mah) not only sounds like a gemstone but is the Latin word for jewel. Gemma is easy to see with the naked eye and its position in the ring (crown) recalls a diamond on a gold band.

Finding Gemma is easy. Using the map from yesterday's blog, you'll see that Arcturus is high in the southern sky around 10:30 in late twilight. Arcturus is the color of a hotdog warming light and one of the sky's brightest stars, easy to find even in a city. It's also the "alpha" star in the ice cream cone shaped constellation Bootes (boh-OH-teez) the Bear Driver. Another way to find Arcturus is to simply follow the arc of the Big Dipper's Handle southward. Gemma and the nearly complete band of Corona Borealis is just shy of two fists to the left or east of Arcturus. Though not particularly bright, the "ring" is still conspicuous because of its distinctive shape.

A sinkhole covers a street intersection in downtown Guatemala City, Monday May 31, 2010. A day earlier authorities blamed the heavy rains caused by tropical storm Agatha as the cause of the crater that swallowed a a three-story building but now say they will be conducting further studies to determine the cause. Last April 2007, another giant sinkhole in the same area killed 3 people. Credit: AP Photo/Guatemala's Presidency, Luis Echeverria

Yesterday the AP published a photo of an enormous sinkhole that formed in Guatelmala City, Guatelmala in the aftermath of tropical storm Agatha which hit the region over the weekend. I know it looks like someone Photoshopped the image but trust me, it's the real thing. Apparently torrential rains from the storm saturated the ground causing it to collapse. One of my co-workers said it looked like the beginning of a black hole ready to swallow the Earth. It's likely that the limestone underlying the region has been eaten away by the weak acid formed when rainwater absorbs CO₂ from the atmosphere. The acid dissolves away the limestone creating voids (caves) which can collapse without warning.

Further out in the solar sytem at Saturn, Cassini sent back this recent image of the small moon Janus above the ring plane and the larger moon Rhea partially obscured by the rings. It's just too pretty for words. Credit: NASA/JPL/Space Science Institute

Posted by: rking@duluthnews.com on 6/1/2010 at 11:36 AM | Comments (0) | Permalink | Edit

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