21 Jan 2007
After sunset tonight and for the next weeks to come, a solitary bright object in the western skies will be making a vain attempt to escape the clutches of the setting sun. It is Venus, the Evening Star, and her path in the sky over the next season will dramatically show us why she has been so popular through the ages in both myth and metaphor.
Venus has an orbit that is permanently parked in the Number 2 spot from the sun after Mercury. Her place in the sky, therefore, takes the bright planet never too far from the Sun from our perspective. If we could freeze the Sun in the noontime sky for a year we could watch Venus go around the sun - passing in front towards the right (the west), then crawling behind to the left (eastwards), coming out from behind to begin the circuit all over again.
Now you can imagine that during those weeks when Venus is to the west of the sun - on the "right" - she precedes the Sun when they both rise in the morning. It is then that our nearest neighbor is called the Morning Star, shining far brighter than any other object besides the Moon.
But months later, as Venus continues to orbit around to the backside of the Sun, she appears to be getting closer to our star every morning, and finally gets so close as to disappear into the fires the Sun.
Just weeks after that, Venus reappears on the other side of the sun, to the east, and follows that Greater Light through the sky.
Now, when the sun sets and the skies darken, Venus, the follower, has seemingly "reappeared" as the Evening Star. As her orbit takes her more and more around the sun, she appears to rise higher and higher in the twilight western sky. It's almost a "Look at me, see how bright and shiny I am!" sort of circumstance, an attitude that lends itself to great stories of human nature.
What Venus doesn’t know is that her current rise into brilliant fame is short-lived; she is destined for a fall back into the sun.
Venus's recurring ascent from and descent into the fires was well known by the Babylonians, and the Sumerians before them. In Babylon the goddess associated with Venus was known as Ishtar, in Sumer she was Inanna.
Inanna's stories are numerous, and can't be described here; not because of the space limitations, but because they were quite racy. She was one promiscuous goddess to say the least.
But one of her escapades, edited here for the family, shows us how nature and human nature unite in myth. E. C. Krupp's excellent book "Beyond the Blue Horizon" describes Inanna's exploits as she attempts to take control of the underworld.
Dressed to kill - literally - Inanna descends into the kingdom of the dead. Unknown to her, she is quickly discovered. Forced to disrobe, she is still unaware that she herself is being prepared for death. She finally stands naked before the magistrates of the netherworld, who find her guilty of attempted overthrow, and she is killed.
But some spirit spies are sent down into the abyss. They find her rotting body and bring her magically back to life. She then ascends again, reborn to former glory.
Sound like any planet we know?
The Bible itself uses the bright planet as a metaphor for the fall of prideful beings.
The prophet Isaiah condemns the king of Babylon in the fourteenth chapter:
How you have fallen from heaven, O morning star, son of the dawn.
You have been cast down to the earth, you who once laid low the nations!
You said in your heart, "I will ascend to heaven;
I will raise my throne above all the stars...
I will make myself like the Most High"
But you are brought down to the grave,
To the depths of the pit.
As you watch the great planet rise higher in the sunset skies over the next weeks, keep in mind the lessons given us from the ancients and painted on the skies: pride goes before the fall.
07 Jan 2007
The last time we were together we learned how the great constellation of Orion was not exclusively a European constellation by any means. Peoples on every continent have thrown their own stories and characters up there into that conspicuous part of the sky.
Now we hit the scientific stories, our best insights into what precisely those points of light and fuzzy clouds really are.
Let's start with Betelgeuse, the reddish-orange star that makes up one of the bright corners of the quadrangle, specifically the star in the upper left.
The name Betelgeuse is possibly derived from the Arabic for "armpit of the central one." Some think it might have come from the Arabic for "shoulder" or "hand," but those interpretations don't cause nearly as many snickers.
What we do know is that Betelgeuse is one enormous star, yes-sirree-bob. It is in its red giant stage, the final act in The Life of an Enormous Star. When a star begins to run out of fuel it goes through some crazy death throes, one of which is to expand. Betelgeuse has expanded so much that if we could put it where our own Sun is, it would swallow up all the planets out to Jupiter. That is one big star.
We're happy it's over 400 light years away, because when it finally self-destructs as a supernova in just the next thousands of years, it will spew lethal radiation for hundreds of light years around it, sterilizing the vicinity. Are we completely safe? We don't know yet.
On the opposite corner of Orion's hourglass figure is Rigel, the "foot" of the Great Hunter. It is the brightest star in Orion, and one of the brightest stars in the galaxy. To be over 775 light years away and still burn that brightly means Rigel is one energy-gushing star.
In fact, bluish-white Rigel is over 90 times bigger than our sun and pours out more than 50,000 times more energy.
From left to right, Alnitak, Alnilam, and Mintaka make up a triplet of other fiery, fast-burning stars, those that make up Orion's Belt.
They are about the same type and size of star as Rigel, telling astronomers that perhaps Rigel and the Belt Stars - and some of the other stars of the Hunter - were formed in the same super colossal stellar womb, the same cyclopean cloud of gas and dust, some ten million years ago.
We can see residual star formation still going on in the most famous nebula in the sky, the aptly named Orion Nebula.
Just below the Belt, and visible to the naked eye, is this cloudy-looking area of intense star birth. A decent telescope will bring out the four brightest stars in the heart of the nebula - the Trapezium. But the whole immense gas cloud is lit up from the energy of just one of those stars.
Theta1 C Orionis - yes, that's its real name - is that crybaby toddler star, the brightest of the four. It screams out so much nasty radiation, specifically ultraviolet, that it energizes the cloud to the point of lighting it up like a lightyears-across neon sign.
It has just millions of years left before it, too, detonates as a supernova.
The whole of Orion is an example of the fleeting nature of constellations. Often they are made of bright, massive stars that live fast and die young. Orion wasn't in the sky when dinosaurs ruled the earth. He won't be there in about 10 million years, by which time the major stars of the Great Hunter will have long since reached their expiration dates.
Like the Orion of mythology, this constellation is destined for a life cut short.
Enjoy it while you can.