Field Trip to the Stars

   During a visit the grandkids who live at the south end of the Gulf of Maine, I was invited to go with them on a field trip with the Science Club. We gathered on the high school football field on a sunny late September morning-- perfect weather for this sort of thing. The teacher, Mr. Dom, would be helping us understand exactly how big our solar system is. 

   Mr. Dom held up a pea. “Imagine this is the sun," he said. "If you hold a pea at arm’s length in front of the sun, it will block out the sun." Then he set the pea on a small square of paper on the goal line. Two feet away he put a piece of paper on the grass.  This is the earth and the moon,” he said. He held a magnifying glass over the paper and two dots appeared. "The earth would be tiny if the sun was a pea."

  Jupiter was a poppy seed 12 feet downfield. Pluto was a tiny dot on a piece of paper 90' further down the field. We followed Mr. Dom another 217' over the opposite goal line where he placed another piece of paper. "This is the Voyager 1 spacecraft launched in 1977 to explore the solar system. This is where it is now, 15 billion miles away, still sending information back to earth. They say it should be good until 2035. And now we're going to visit our nearest star, Proxima Centuri. Everybody on the bus!" 

   How far could this be, I wondered. Good thing I brought a book. We got on the freeway and about an hour and a half later I noticed we were in New Hampshire. After another hour and a half we pulled over just north of North Conway. "We're here," Mr Dom said. "If the sun was a pea, you'd have to drive 125 miles to get to our nearest star." Outside the bus he placed a radish seed. "Proxima Centuri is much smaller than the sun," Dom said. "It's a red dwarf, only visible with a large telescope. Don't worry about it, you'd have to be south of the equator to see it. We know it has a planet about 3.5 centimeters away on this scale.

  "So where's the closest visible star?" Someone asked.

"Good question. Back on the bus." Everyone groaned. But it was only another five miles up the road. "This is Alpha Centuri," Dom said, as he placed a pea on the ground. It's slightly larger than the sun. The brightest star we can see in the northern sky is Sirius. It would be the size of a marble. Proxima Centuri was 125 away. Sirius would be twice as far. We won't go to Sirius today. Betelgeuse, not the movie, is the reddish star in the constellation Orion. On our scale it would be the size of a car. To get there you'd have to travel to the west coast of Spain. But from here you'd have to travel west across the Pacific and southern Asia to get to the west coast of Spain. It's really far away.

  "One more piece of information. Remember Voyager I back on the football field? It's taken the spacecraft 47 years traveling at 38,000 mph just to get to the end of the heliopause of the sun. At that rate it's going to take another 77,000 years to get to Proxima Centuri, our closest star. Any questions?"

  "Mr Dom? On this scale, where is the nearest McDonald's?"

  Mr Dom sighed. "It's about one light year away, but I know a shortcut. Everybody on the bus!"

Voyager 1– milk train to the Milky Way