Friday, December 21, 2012

An Old Friend

The dark road curved beneath my headlights, and then straightened into a long trough between the trees. An old friend lay resting there, just above the pointed tips of spruce and fir.

Orion has been my favorite winter constellation for many years. Sometimes subtitled “The Hunter,” it seems apt that Orion is lying on his side tonight, perhaps resting up for an early morning of deer hunting. Traditionally, of course, his quarry was more mythical—chasing the beautiful seven sisters of Pleiades, doing battle with Taurus the Bull, fighting a scorpion sent to tame his ego, or hunting the constellation Lepus the Hare.

In Australia and New Zealand, Orion appears upside down, and his distinctive belt and sword are imagined instead as a cooking pot. Perfect for the end of hunting season! Closer to home, some in the Ojibwa culture call this constellation Kabibona'kan, the Winter Maker, as its presence in the night sky heralds winter. Indeed, he can be seen from November to February each year. 

Of the four stars that form the rectangular shape of Orion’s body, Betelgeuse is my favorite. This reddish colored star forms Orion’s right shoulder, assuming the hunter is facing us. The red color is not an optical illusion, and it is not due to rusty iron, as is the color on Mars. Betelgeuse is a type of star called a red supergiant, and it gives off most of its light in the near-infrared wavelength, which we cannot see. It is at the opposite end of the spectrum from ultra-violet (UV) light, which is also invisible to humans. Only a small portion (13%) of Betelgeuse’s light is visible to our eyes.

Last week I discovered that if we could see UV light, we could tell male chickadees from females. This week I discovered that if we could see infrared light, Betelgeuse would be the brightest star in the sky. My narrow spectrum of human vision feels so limited, even forgetting that I have been nearsighted since 3rd grade! What is amazing is that we have built surrogate “eyes”—instruments that can “see” these wavelengths and translated them into beautiful images in the visible spectrum of colors.

With the help of these instruments, astrophysicists have seen hotspots and other features on the surface of Betelgeuse. One astronomer characterized Betelgeuse as “an enormous seething restless cauldron of belching plasma.”

Something that violent can hardly last very long. Indeed, Betelgeuse has already used up its supply of hydrogen for nuclear fusion. This means heavier elements are fusing together, and the star’s core is compressed into a hot, dense, ball, while other outer layers have expanded into the huge red mass we see today. Stars like this are rare—we only know of 200 in our Galaxy—because they do not live very long.

At about 10 million years old, Betelgeuse is thought to be near the end of its life. It will likely explode into a supernova within the next million years. When it does, it will be visible even in the day, brighter than the moon, and to an outside observer would outshine the entire Milky Way Galaxy.

While I admire the superlative nature of stars like Betelgeuse, I often think about how wonderful our own star is. Our Sun is just the right size, just the right distance, just the right age, and just the right brightness to make life on Earth possible.

This time of year, when gray clouds can hang low for many days in a row, a splash of sunlight on my face feels like wonderful gift. I am even grateful for when the Sun is not around. Crystalline stars and shimmering Northern Lights appear closer in these long winter nights. This time of year, Orion is really a perfect friend. He keeps me company on dark lonely drives, sparkles handsomely above my doorstep, and after hanging out with him, I can still get to bed early!

This world provides us with much to be thankful for. 

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