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What Northern Hemisphere Astronomers Are Missing From the Southern Hemisphere
creimer (824291) writes The New York Times Sunday Review has an interesting article on the astronomical night life when viewed from Sao Paulo, Brazil, featuring a treasure trove not visible to astronomers in the Northern Hemisphere: "Yet the Southern Hemisphere claims the three brightest stars of the night sky: Sirius, Canopus and Alpha Centauri. Canopus belongs to the Carina constellation, notorious for two things: the Carina Nebula, four times as large and even brighter than the famous Orion Nebula, and the star system Eta Carinae, which is expected to burst as a supernova or hypernova sometime in the next thousand years. (A scientist told the BBC that the explosion would be so bright that you would see it during the day, and you could even read a book by its light at night.) Alpha Centauri and Beta Centauri, the 11th-brightest star, are called "The Pointers," as they form a line in the sky to the constellation Crux (the Southern Cross). Crux is the smallest of all 88 constellations but one of the most distinctive. It is visible at practically any time of the year in all of the Southern Hemisphere."
The light pollution where I live is so bad that only a few stars are visible on a clear night. I frequently wish all the street lights could be turned off for a change. I doubt that the switch to LED street lights will improve things. In fact, I imagine it will make things worse for the local observatory (Lick) since it is relatively easy to filter out sodium.
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Crux is very useful for navigating at night. From wikipedia:
In the Southern Hemisphere, the Southern Cross is frequently used for navigation in much the same way that the Pole Star is used in the Northern Hemisphere. Alpha and Gamma (known as Acrux and Gacrux respectively) are commonly used to mark south. Tracing a line from Gacrux to Acrux leads to a point close to the Southern Celestial Pole.[3] Alternatively, if a line is constructed perpendicularly between Alpha Centauri and Beta Centauri, the point where the above-mentioned line and this line intersect marks the Southern Celestial Pole. Another way to find south, strike line through Gacrux and Acrux, 3 1/2 times the distance between Gacrux and Acrux, directly below that point is south.
They sentenced me to twenty years of boredom
I mean, yes, it's true. And yes, it's interesting. But ... news?
Yeah, not really. In Australia I have known for decades that we have a great opportunity for our telescopes because we see portions of the sky that are out of sight for all you Northern Hemisphereans. Hardly news. That is also why bases in Australia are very useful during space flights, when the capsules or whatever go out of range for the Nrothern Hemisphere.
Oh, and it's summer here - a balmy 25 degree Celsius (=77 degrees F). And I live three minutes walk from the beach ....
I am anarch of all I survey.
As you might imagine, there is a section specifically on Crux:
In your mind, draw a straight line through the axis of the Cross, through the tip and across the sky. You will find the arrow is pointing at another bright star. You cannot fail to identify this star, Achernar, because it is the only first-magnitude star in that part of the sky. Approximately halfway along the imaginary line between the cross and Achernar is the south celestial pole... Once you have established where the celestial pole is, you can determine your latitude. The celestial pole is always a number of degrees above the horizon equal to the latitude at which you are standing. Surprisingly, you don't need complex equipment to make this measurement. Polynesian navigators used a notched stick held at arms length, or sometimes nothing more than the outstretched hands and fingers.
Hej! Nasi tu byli!