Winter Nearly Springs By
27 02 05
I just about missed it. Winter nearly whisked by without a mention here of some of the wonders of the southern hibernal sky.
That was a close one.
Now, here’s the lowdown on what’s up in those glorious skies at the end of this cold and very wet month of February.
Let’s assume the best, that in the next couple nights we will have cloudless skies. The nearly three-week-old moon doesn’t rise until late evening so star gazing and planet seeking should be very nice.
And let’s use Orion as our wayfinder for our mini-adventure. You’ll find our hunting friend in the southwest skies, that great stellar quadrangle cut through by his famous belt.
At his “top left” shoulder there’s the famous red giant star, Betelgeuse. “Giant” is the right description for this dying star since he is over 600 times bigger than our sun. Put him where our sun is and he’d swallow all the planets out to and beyond Mars.
Opposite Betelgeuse, to the lower right, is bright blue Rigel. Both Betelgeuse and Rigel each pour out more energy than 50,000 suns. That’s why they can abide at their great distances of hundreds of light years – thousands of trillions of miles - and still appear as bright as they are.
But the energy leader of the Orion clan is that middle star in the belt. There lies Alnilam, a star that spews more than 112,000 suns worth of energy. It’s a fiercely violent star but is dimmer than the other stars in the great family because of its distance – more than 1350 light years from earth.
A quick trip through Orion would be incomplete without at least a mention of the most famous star nursery in the sky, the Orion Nebula.
Located just below the Belt, here are dozens and dozens of stars being formed in a luminous cloud of dust and gas. But, amazingly, only one star is lighting up the entire cloud, a bright O-type star in a tiny cluster of four named the Trapezium Cluster. One can see both the Nebula and the four tiny Trapezium through even inexpensive backyard scopes.
Closer - much closer - to Earth is the intensely bright star almost due south this evening and a little to the east of Orion. That is Sirius in Canis Major. This beauty is not so bright because it’s so big, but because it is so close. A mere stone’s throw 8.6 light years away, it is the closest star we can see this far north, besides the sun of course. (In case you’re wondering, southern folks can see the Proxima and Alpha Centauri pair, the closest stars to Earth overall.)
Now our next stop on the tour is a planet, but it will take a little sleight of hand to get there. Imagine a line made from the top two stars of Orion - from Bellatrix at the upper right through Betelgeuse at the upper left. Holding your arm out and spanning your hand, imagine a line extending out to the left from Betelgeuse, curving slightly upwards, two hands spans worth of sky away.
There you will find a bright golden “star” near two bright, but slightly dimmer stars. That would be Saturn, the ringed beauty. The second largest planet in the solar system, it is easily spotted through amateur scopes and is a favorite at star parties.
Its main moon (one of over 30) is Titan, the rare satellite that can brag of its own thick atmosphere. Titan has been making a lot of news lately since we’ve managed to land a probe there, just weeks ago.
The spacecraft Cassini, which finally arrived in a comfortable orbit around Saturn last year after its launch back in 1997 - it takes a while to get certain places - dropped a probe named Huygens down onto chilly old Titan to see what makes it tick.
You can see all the great images from both Cassini and the Huygens probe of Saturn’s amazing rings, Titan’s spooky other-worldliness, and other bizarre creatures in Saturn’s zoo of satellites at the website for the mission: http://saturn.jpl.nasa.gov.
Hope our little tour of the southern skies was enlightening. Our next scheduled planetary package tour will be in spring starring the King of the Giants – Jupiter. We’re taking reservations now.