STARRY NIGHTS
by Gary Boyle
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July 21, 2003
OTHER WORLDS
Situated in the icy cold of space, two giant planets slowly circle a star. These extraordinary worlds orbit around 316 million and 560 million kilometers respectively from its parent sun. They revolve around this star once in three and seven years. You might think this is an opening scene from a Steven Spielberg movie. After all our solar system consisting of nine planets is unique in our galaxy - right? Wrong.
The scenario I just portrayed is real. These worlds measuring about eleven and eight times the size of the earth live around a star named 47 Ursae Majoris, part of the constellation of the Big Dipper. This point of light is about 46 light years from us. A light year (ly) is the distance light travels in one year, close to ten trillion kilometers. The star light from 47 UMa you see tonight actually left around 1957, the year of the Chevy.
Every star in the night sky has a different life story. They exhibit different age, dimensions, temperatures, brightness, evolution and color. 47 UMa is however very similar to our closest star - the sun. The sun appears bright as a result of its close proximity to us. Imagine holding a candle at arm's length. Now have a friend hold it about a kilometer away - it now appears so dim you require binoculars of a telescope to see it.
Estimated at seven billion years old 47 UMa surface temperatures are approximately 5,500° C very close to our sun's 5,800° C. It is also a bit smaller then the sun. If the earth represents a pearl on a necklace, you would need a string consisting 109 beads to stretch across our sun's belly. If the sun was hollow like a basketball, over a million earths would fit inside.
So how do astronomers know about other worlds? As instrumentation becomes more sophisticated, scientists have the ability to fine tune they measurements, thus leading them to new discoveries. About ten years ago scientists theorized that if a star had planetary bodies around it, a minute gravitational wobble could possibly be measured. This theory was based on the Doppler shift.
The best example of this would be the sound waves of a moving train's whistle. As the train approaches you sound waves are tightly compressed like a spring thus producing the high pitch sound. As the train recedes the wavelengths are long (stretched out spring) and the tone is lower. With this in mind they began to look at and measure some 120 stars like our sun. As an object approaches you it appears as a blue shift and if it recedes, it red shifts but to a lesser degree. These distant specks of light were within 200 light years from earth.
The first star detected with this questionable wobble occurred in October 1995. The target star is named 51 Pegasi and is located in the constellation of Pegasus - the winged horse. This sun lies 50 light years from us, literally in the neighborhood. It has one Jupiter size body orbiting it at very close distance. The planet's hostile environment would not sustain life.
Up to now astronomers have been only able to measure a wobble. From this data they can deduce how many bodies are in orbit, its distance from the parent star along with its period of rotation. Because of great distances, the planets themselves can never be photographed. Imagine for a second trying to locate a firefly next to nuclear explosion three thousand miles away.
Almost four years had passed. By September 1999 the total number of discoveries had grown to19 stars with siblings around them. The next discovery was by far unique. A star with catalog number HD 209458 was measured on the nights of Sept 9 & 16, 1999. Astronomers noticed a 1.7% dip in starlight. This was the first time ever, that evidence pointed to a planet circling a distant star. Situated 153 light years from us, HD 209458 sole planet is incredibly close to its solar furnace. Circling at only 7 million km it crosses the star's face every 3.5 days.
As of July 1st, 2003 the list of discoveries has drastically risen to 110. The latest find was not part of the search criteria of a couple hundred light years but truly bizarre. An ancient planet has been discovered orbiting two burnt out stars in a globular cluster called M4. This tightly knit ball of 10,000 stars is located 5,600 light years from us in the constellation Scorpius. We can only detect the Jupiter sized monsters but given time, astronomers will have the capability of finding smaller ones and eventually even earth sized.
So the next time you are stargazing at a dim flicker of light thinking there might be a world in motion, who knows where might be someone on that world looking at our flicker of light and thinking the same. The question of "are we alone in the universe", just took on a whole new outlook.
