“But if the Sun can pull objects, why doesn’t it pull them all the way to it?” Billy asked.
“That’s a good question, Billy. And the answer is: some are pulled into the Sun, just like on occasion some asteroids and meteors come crashing into the Earth; however, some objects fly off into space, and sometimes objects get stuck in an orbit when their centripetal force and centrifugal force balance each other out. I’ll teach you about those forces later, but think of it this way: the object’s momentum, which tries to carry it away from Earth, is balanced by gravity, which wants to pull it to the Earth.”
“What’s a meteor, Miss Hutchinson?” someone asked.
“A meteor is a small piece of an asteroid. And if it enters the Earth’s atmosphere it is called a meteoroid. One astronomy article I recently read says that most meteoroids burn up in the Earth’s atmosphere before they can hit the ground. But some do not. It depends on their size. If they are big enough they don’t completely burn up before they reach the ground; and those are called meteorites. Regardless, they also call meteors that enter the Earth’s thick atmosphere shooting stars, because they glow like a star when they burn.”
“Why do they burn?” Billy asked.
“Because of friction, Billy. The objects are going so fast that they get hot when they bump into the air molecules in the Earth’s atmosphere. It’s like when you go horseback riding, or sledding: The faster you go, the more wind you feel on your face. Well, that wind is really the air molecules hitting your face. If you could go fast enough, the wind would eventually burn your face. Of course, you cannot go fast enough to get a real bad burn. But, as you all know, you can go fast enough to get a minor windburn.”
“What are air molecules, Miss Hutchinson?” a 4th-grader asked.
“Our atmosphere is made up of many different air molecules and atoms: like oxygen, hydrogen, and nitrogen,” the teacher answered. “Nitrogen is the most abundant, but it’s oxygen that is the most critical for us. We all need to breathe oxygen to stay alive; we, in turn, all exhale carbon dioxide, which plants and trees need to grow. And they do the opposite of us by absorbing carbon dioxide and then emitting oxygen into the air. But you’ll learn all about that in high school, so let me return to my lesson on the Universe. Now, where was I?”
“You were talking about the Sun pulling things, Miss Hutchinson,” Arlene said.
“Oh, that’s right. As I was saying, the Sun’s pull can capture an object and keep it in an orbit around itself forever, if the conditions are right. Like what happened with the Earth and the Moon. It depends on the size of the object, the speed and direction of that object; and the distance the object is from the Sun when it flies past it. The size of the orbit and the amount of time that the object takes to make one circle around the Sun depends on those things. Obviously the conditions were just right for the Earth to capture the Moon, and for the Sun to capture the eight planets that orbit it, including Earth; and they were just right for many comets as well.”
Miss Hutchinson decided that it was now time to explain centripetal force and centrifugal force in detail, and to talk about how the planets and other objects travel in an elliptical orbit around the Sun. Although she was teaching The Universe to her 6th-grade class, she didn’t realize that there was a 3rd-grader paying attention as well; or just how impactful her lesson was going to be on that child.
Chapter 28
Halley’s Comet
It was from Miss Hutchinson that Leona first heard of Halley’s Comet, or the “four-score-minus-four comet,” as the teacher called it. She was working on her math assignment while listening to Miss Hutchinson’s 6th-grade lesson. The things she was hearing about the Universe were all extremely fascinating to the 8-year-old’s curious mind, but when the teacher mentioned the name of a comet that was occasionally visible from Earth, Leona’s eyes widened and she stopped what she was doing, listening much more attentively to her teacher.
“Except for the planets, Halley’s Comet is the most famous object to circle our Sun,” Miss Hutchinson said. Halley’s Comet happens to be the most well known comet of them all,
Although some pronounced it Hal-lee’s Comet, Miss Hutchinson pronounced it Hay-lee’s Comet, as did most Americans and even some Europeans. Hearing her teacher’s pronunciation of the comet’s name, Leona assumed that its spelling was the same as her own; after all, it sounded the same. And the little girl also assumed that Edmund Halley, the English astronomer who discovered it, had to be an ancestor of hers. It wasn’t until later that she learned the spelling of the early astronomer’s surname was different from hers. Even then she thought that maybe Edmund Halley’s descendents had moved to America and changed the spelling of their name, as immigrants often did in an attempt to avoid being subjected to real or imagined prejudice in the new land.
Margaret had heretofore explained to her children about some of the problems certain immigrants faced during, and after, the immigration process: in particular, the Irish. However, Leona had never heard of Englishmen being the subject of prejudice in America, especially one with such an innocuous ethnic name as Halley. Then Leona remembered something else her mother told her about immigrants:
“When they were being processed at Ellis Island, New York, some of them wanted to change their names to more American sounding names, and other were forced to do that to appease narrow-minded immigration officers. Even if some of them wanted to keep their birth names, they were afraid of what would happen if they argued with immigration; so they were caught between the devil and the deep blue sea.”
“Huh?” Leona said.
“It means the same as being caught between a rock and a hard place, Leona,” Margaret explained.
“Oh,” she replied.
Even though what her mother said made sense, Leona could not imagine that anyone would intentionally change a simple name like Halley to Haley. There was something else that Leona remembered her mother saying that made much more sense to her. She remembered Margaret say that careless immigration officials at Ellis Island often made spelling errors when they wrote down the names of immigrants—something that seemed more likely to Leona in this particular case—and once an error was made and the document was stamped, the misspelled name became the legal name of the new immigrants and they had no choice but to live with it. Regardless, on this marvelous day in 1918, Leona thought that astronomer Edmund Halley’s name was spelled the same as hers, and thus the little girl was convinced that he must be her ancestor.
So she listened intently as Miss Hutchinson talked about his comet.
“Another thing to remember,” she explained, “is that the closest point an object gets to the Sun is called its perihelion and the farthest point from the Sun is called its aphelion. Halley’s Comet flies deep into the Galaxy and, remarkably, its aphelion is even further away from the Sun than Neptune’s, while its perihelion is less than Earth’s.”
“Miss Hutchinson, you said that the Earth takes one year to travel around the Sun. If Halley’s Comet travels so far into the Galaxy, how long does it take for its trip around the Sun?” Billy asked.
“That’s another excellent question you’ve asked, Billy. Remember the unusual nickname I gave the comet? I made it up as a memory aide for you children because I wanted you to be able to figure out for yourself when it will return again.”
“You mean when you called it the four-score-minus-four comet?” Arlene said.
“That’s right. Now how long do you think it takes to orbit the Sun?” the teacher asked.
After seeing none of the kids raise their hands, Miss Hutchinson offered help.
“Okay, I’ll give you a clue. Who remembers how Lincoln’s Gettysburg Address begins?”
“Oh! I remember that, Miss Hutchinson,” Arlene answered. “My mother and father helped me memorize it.”
“Okay, Arlene, why don’t you recite the opening sentence for the class a
nd then see if you can answer my question.”
“Yes, Miss Hutchinson. The first sentence is: Four score and seven years ago, our fathers brought forth on this continent a new nation. For the life of me, I can’t remember what a score is, but I think I can figure it out.”
“Good. Go ahead and do your best,” the teacher said.
“Let’s see, the Declaration of Independence was signed in 1776, and Lincoln’s Gettysburg Address was written around 1864, I think?” Arlene said as she picked up a pencil to make a calculation. “So if I subtract 1776 from 1864, I get 88 years. Now if I subtract 7 years from 88, I get 81. And dividing 81 by four gives me 20.25 years. So a score must equal twenty years, and that means—just a minute, 1776 plus 87 equals, oh yes—the way I figure it, the Gettysburg Address was really written in 1863, not 1864.”
“That was excellent, Arlene,” the teacher remarked. “Now, how long does it take Halley’s Comet to make a trip around the Sun?”
“Since you call it the ‘four-score-minus-four comet’, it must take 80 minus 4, or 76 years for it to orbit the Sun,” Arlene answered.
“Excellent! And now, how many years are there between the perihelion and the aphelion?”
“It should be about one-half of 76—or 38 years,” Arlene answered.
“Right again! Now, class, give Arlene a big hand for coming up with the correct answers; and don’t be surprised if you need them on your next test.”
—1—
Leona watched Arlene beaming with pride as she and the other children applauded her sister’s accomplishment. After the applause died down, Miss Hutchinson continued.
“Thank you, Arlene. Another way to think of it is that Halley’s Comet will come within view of the Earth only once every 76 years. And since the last time it was close enough to Earth to be visible was in 1910, what year will it be visible again?” the teacher asked.
When Leona heard that 1910 was the last time Halley’s Comet visited Earth, she exclaimed: “That’s the year I was born, Miss Hutchinson.”
At that point, the 3rd-grader suddenly remembered that the younger children were not supposed to speak when Miss Hutchinson was teaching a lesson to the older ones.
“Oh, I’m awful sorry, Miss Hutchinson,” Leona apologized. “I forgot that I wasn’t supposed to talk.”
“That’s quite all right, Leona. You had a really good reason for speaking up, this time. And that’s a really good way for you to remember the last time Halley’s Comet visited Earth, isn’t it?”
Leona smiled, but the next thing the teacher said puzzled the 8-year-old.
“Maybe because you were born the year the comet was last visible, it will be a good omen for you. Do you think so, Leona?”
“I don’t know, Miss Hutchinson. What’s an omen?”
“Come to think of it, I guess you would be a little too young to know what that word means. Does anyone else know what it means? No? Then, Arlene, would you look it up in the dictionary and read the definition to the class?”
Arlene got up from her desk and walked to the corner of the room where a very large copy of Webster’s Dictionary was sitting on a small circular table. She picked up the heavy maroon-colored book, carried it back to her desk where she looked up the word omen and read from the dictionary.
“Omen. A circumstance or occurrence thought to portend future good or evil,” Arlene read.
“And what does portend mean?” the teacher asked.
Arlene shrugged her shoulders and began thumbing through the dictionary once again, until she found the word portend.
“Portend. To indicate beforehand, to presage, as an omen does; to foreshadow,” she read.
“Thank you, Arlene. Now, Leona, do you think that Halley’s Comet appearing the year you were born will foreshadow something good or evil happening in your future?”
“I don’t know, Miss Hutchinson, but if it does I sure hope it’s not evil,” she replied, causing her teacher and classmates to explode into laughter.
“I hope so too, child. In fact, I’m sure the comet was a good omen for you,” the teacher was quick to assure her young pupil after the laughter subsided. “Now, let’s get back to the lesson. Can you tell me when the comet will be back?”
“In 68 years,” Leona answered.
“Good, I see you were paying close attention.”
Paying attention was an attribute that the young teacher greatly appreciated in her students; even the ones for whom the current lesson wasn’t meant. As long as they didn’t neglect their own subjects, she was pleased, and indeed even encouraged, when either the younger or the older children listened to her teach another class; Leona often pleased Miss Hutchinson in that way.
“Now can anyone else tell me what year that will be?”
“It will be 1986, Miss Hutchinson,” Arlene said.
“That’s right.”
When Leona remembered that Grandma Eunice was born in 1845 and was now nearly 73 years old, the 8-year-old realized that in 1986, when Halley’s Comet returned, she would not be that much older than her grandmother’s current age, and could still be alive and able to see it with her own eyes.
“If only I can live to be 76,” she mumbled softly to herself, but not soft enough.
“What did you say, Leona?” Miss Hutchinson asked.
“I was just thinking, Miss Hutchinson. In 1986 I’d be 76, so maybe I’ll be able to see Haley’s Comet for myself.”
“I hope you do, young lady, but I don’t think I’ll be watching it with you.”
“Why not, Miss Hutchinson?”
“Because, dear, I’d be ah-hundred-and-four-years-old then.”
And, while laughing, the teacher added: “I’m planning on living a very long life, but not quite that long.”
Then imitating a frail, elderly woman’s quivering voice and actions, the teacher added one more thing.
“If I live to be that old, my eyes will probably be so bad that I won’t be able to see the Sun, let alone Halley’s Comet.”
And with that the classroom again exploded into laughter. After it died down, Leona raised her hand.
“Yes, Leona?” Miss Hutchinson said.
“When was the comet visible in 1910?”
“Just a minute, dear, and I’ll look it up.”
The teacher thumbed through her books and said: “Oh, here it is. It says that Halley’s Comet was at its perihelion on April 20th, so that means….”
“That was the day before Mark Twain died, and only six days before I was born,” Leona interrupted her teacher.
“Then the comet must have been very bright the night you were born, Leona. In fact, it says right here that in 1910 it was the brightest it’s ever been. I guess Halley’s Comet was a good omen for you after all.”
Leona sat mesmerized for a while, and then asked: “Miss Hutchinson, how long can I see it in the sky when it returns in 1986?”
“That’s another good question, and one that I anticipated. The answer is that it can be seen by the naked eye for about a month, or maybe two, although very faintly for much of that time. You really need a telescope to see it well. When it approaches the Sun it be can be seen quite easily for a two-week period though; and after it circles around the Sun it can be seen again for about two more weeks as it heads away on its journey again. During those periods the comet is close enough to the Earth to be visible, and there are about three months between those periods of visibility. However, astronomers can see it for a much longer period of time, sometimes up to six month or more. But it can only be seen at night, even by serious astronomers.”
“What are astronomers, and why can they see it longer than us?” Leona asked.
“An astronomer is someone who looks at the stars through a magnifying instrument called a telescope. It works like binoculars, except it is more powerful and allows someone to s
ee objects in the sky that we cannot see with the naked eye. The first telescope was made in 1608 by a Dutch lensmaker named Hans Lippershey. And, in 1609, an Italian physicist by the name of Galileo Galilei built a larger one to look at the stars more closely. So he was the first real astronomer.”
“Do you have a telescope, Miss Hutchinson?” Arlene asked.
“No, Arlene. Although, I’ve often dreamed of owning one. But they’re so expensive that there’s no way I can afford to, not even an amateur telescope; not on a teacher’s salary.”
“What’s an amateur telescope?” Billy asked.
“Well, Billy, there are two types of telescopes: smaller, less expensive ones that amateur astronomers like you and I would use; and larger, more expensive ones that eminent professional astronomers use. An amateur telescope is good if you are curious and want to get a closer look at objects. But if you are really serious about studying the sky you need to use a professional-quality telescope. But as I said before, even amateur telescopes are a little out of my price range, at least the good ones, and a professional telescope is totally out of the question.”
“What does a professional astronomer do; just look at the stars?” Arlene asked.
“Not just look at the stars, Arlene. A professional astronomer studies them, and the other celestial objects we have talked about today.”
“How do you get to be one?” Arlene asked.
Journey With the Comet Page 26