David M. Schwartz
The amazing, engaging, math exponent
'Tis the season. The rotting season.
You thought Halloween was full of ghosts, goblins and ghouls? Well, wait until the post-Halloween season. This is when your Jack O' Lantern begins its ghoulish decline. It starts as a pumpkin and it ends as a heap of goo. This is scary!
Now is when your Halloween pumpkin begins to rot. Don't get me wrong. Rot is not gross. It is a beautiful thing—beautiful in its own deliciously disgusting way.
You start with a proud Jack, a plump, shiny-skinned pumpkin. Halloween is over so you leave it on your porch, or inside by the window, or maybe you toss it into the garden or onto the compost heap.
It attracts some visitors. A squirrel. A pair of mice. A scurry of sow bugs. They chew the skin of the pumpkin, leaving moist, rough surfaces, just perfect for the next wave of invaders: the molds and fungi and bacteria that start to grow. There are dozens, even hundreds, of types of organisms waiting to sink their "teeth" into pumpkin flesh as soon as the conditions are right. One kind of invader changes the conditions of the flesh to make it perfect for the next one. Meanwhile, the poor pumpkin is looking less and less like a pumpkin. Its skin turns to shades of black, gray and white, with only a few patches of dull orange. Its shape collapses into a heap, then a pile of mush, and then . . . well, no shape at all.
Do you think rot rots? Imagine what your life would be like if things didn't rot. You'd be tripping over all the old pumpkins, not to mention mice, eagles, tomato plants, oak trees and everything else that ever walked, flew, swam or grew upon the earth. Their dead bodies simply wouldn't go away! Worse, their nutrients would be locked forever inside. The energy in the molecules they are made of would be unavailable to any other living things. Rot, properly known as "decomposition," releases all those good vitamins, sugars, proteins, carbohydrates and energy so that they can be used by next year's pumpkin, which will grow from the seeds of last year's pumpkin. Mice and eagles, tomatoes and the trees in a nearby forest can grow and reproduce because nutrients and energy pass through complex food webs from plants to the animals that eat those plants, to other animals that eat those animals.
It's all possible because of rot. So you see, rot doesn't rot. Rot rocks!
David is the author of > 50 books on math and science, including his newest, rottenest title, Rotten Pumpkin. For more information, click here.
David is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
by David M. Schwartz
the amazing, engaging, math exponent
A light year is not a year that has gone on a diet. It is not a year that’s been trimmed to 300 days. It’s not a year spent under high-wattage lamps. A light year isn’t any kind of year.
A light year is a distance. It is a vast distance; the distance light travels in a year. To appreciate a light year, you have to understand how fast light travels.
The speed of light is truly mind-boggling: 186,000 miles per . . . second. That’s “per second,” not “per hour.” In one tick-tock second, light travels a distance of 186,000 miles. If it could go in circles, it could travel around the earth more than seven times in just one second! But light travels in straight lines, not in circles. Imagine something traveling that fast in a straight line—not for a second, not for a minute, not for an hour, not for a day, but for an entire year. The distance it goes in that year is called a light year.
A light year is a convenient unit of measure when distances are enormous. You could talk about the same distances in miles. It's about 5,878,499,810,000 (5 trillion, 878 billion, 499 million, 810 thousand ) of them. But these measurements are so large that they are unwieldy. It's much easier to just name that enormous distance with two simple words: a "light year."
The star closest to our solar system is Proxima Centauri. Some of the light that leaves Proxima Centauri goes to Earth, cruising along at 186,000 miles per second. At that speed, light takes about 4.2 years to get to Earth from Proxima Centauri So how far away is Proxima Centauri? It is 4.2 light years away.
To give you an idea of how far that is, imagine going to Proxima Centauri in a spaceship traveling at the speed of the space shuttle — about ten miles per second. (That’s much faster than airplanes can fly.) You would get there in about 70,000 years.
Our Sun is much closer than Proxima Centauri. It is 93 million miles away. There is another way to refer to the distance from the earth to the Sun. Light leaving the Sun takes about eight minutes to get to Earth, so we say the Sun is eight “light minutes” away. If you traveled at the speed of light, you could get there in eight minutes. Have a nice trip!
© David M. Schwartz, 2014
David Schwartz has been fascinated by big numbers and big distances ever since he was a little boy riding his bicycle, wondering “How long would it take for me to ride to Proxima Centauri, 4.2 light years away?” He wrote about light years in his math alphabet book G Is for Googol.
David is a member of iNK’s Authors on Call. He can visit in your classroom via interactive video conferencing. Learn more here.
MLA 8 Citation
Schwartz, David M. "What Is a Light Year?" Nonfiction Minute, iNK Think Tank, 14 Sept. 2017, www.nonfictionminute.org/the-nonfiction-minute/what-is-a-light-year.
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