SCIENCE NETWORK NEWS Vol. 4, #1 August 1991 CIRCE, College of Education, UIUC

Jack's Summer Journal (Some Answers, More Questions)

Please, send us your pupils' summer mathematics and science questions, and your own, too!

A Lake Michigan Beach

Sitting on the beach at Hoffmaster State Park, Michigan, my wife and I wondered, why did the sun set so slowly in June? It was nearly "ten o'clock at night," as they say, closing time for the park, and the sun was still above Lake Michigan. Ten o'clock at night Eastern Daylight Time was really nine o'clock Central Daylight Time. We had moved from the eastern pan of the Central Time Zone to the western Part of the Eastern Time Zone. Now, just stepping across the border between Indiana and Michigan can mane the sun set an hour later. But also, we were a lot farther north than in Champaign. Going north in June can lengthen the daytime a lot. (During World War II, I lived inside the Arctic Circle on Baffin Island, Canada, and the sun stayed up 24 hours every day in June.) A few minutes later, near our campsite, we saw Jupiter, Venus, and the crescent moon close together. Why does the setting sun or rising moon look so big?

We love sassafras trees with some leaves shaped like mittens. We have one in our backyard. So we noticed a lot of them along the path and the edge of the woods at the beach. At the Nature Center at Hoffmaster State Park we found a description of the pine/oak woods along the beach and the maple/beech forests further inland. The pine/oak woods were needed to prepare the soil for the maple/beach forest. I had read about this succession of one kind of woods following another, fifty years ago in a book called Bio-Ecology, by Clements and Shelford, ecologists at the University of Illinois. But why was there no mention of the sassafras? And what were the unmentioned sassafras trees doing all along the beach and the path to the beach? We asked the park ranger on duty and got no answer as to why they hadn't been mentioned in the nature center. There was, in fact, a large sassafras tree right in front of the nature center. This is a puzzle I am still working on.

Airplane Earache

Flying to Hawaii for a family reunion, my wife and granddaughter complained bitterly about the pain in their ears as the plane came down from 35000 ft.

Can you find out what happened to their ears?

Hint: colds and allergies often clog Eustachian tubes. The air pressure on the outside of the ear increases rapidly when the plane comes down.

Touristic Pollution?

Hanauma Bay was less full of marine life and colorful reef f ski, than it had been 25 years ago, more full of very plain looking mullet and of tourists feeding them bread and frozen peas against the warning of posted signs. There is a full parking lot rule--no more visitors after the lot is full.

There are reported to be daily changes in aquatic visibility: murky at night and clearer in the morning. Why?

The water off Ha'anapali on Maui is reported to be exceedingly clear. Why?

More questions: There is a large tidepool at Onekahakaha Beach, near Hilo, where I had once also collected marine invertebrates, and where I had later worried about all the bagasse (what's left after sugar cane has the sweet juice squeezed out of it). Now it was almost sterile several years after the sugar mills had stopped dumping bagasse into the ocean. Why? More questions: How long will the life in that tide pool take to recover? Will it?

A Total Eclipse

As the moon circled around the earth, passing between the earth and the sun on July 11, the shadow of the moon, only about 150 miles wide, fell on the Pacific Ocean. It crossed the Island of Hawaii, "the Big Island," from West to East just after sunrise, and crossed the rest of the ocean on the way to Mexico. Going down through Central America, it entered South America just before sunset.

It will be many months before the shadow of the moon again strikes the earth (see page 4), because each month, when the moon goes between the sun and the earth, its shadow will pass a little above the north pole or a little below the south pole of the earth. Sometimes the moon's shadow will dwindle to nothing, when the moon gets farthest away from the earth.

Fortunately, I was attending a family reunion with about fifty people, including 16 children below the age of nine, in Hilo, on the Big Island. We all got in a school bus by 1:30 the morning of the eclipse and rode over to the dry side of the Big Island to get away from the clouds and rain usually found in Hilo.

Unfortunately, there were some clouds in all parts of the island that morning; even a haze, from the Philippine and Japanese volcanoes, stretched above the worlds' largest collection of powerful telescopes on Mauna Kea, the highest mountain on Hawaii. For us, on the beach at the northwest part of the island, the clouds came and went, and we looked at the sun through special glasses, darker than welders' glasses, so dark we could not see anything else through them.

A Simple Experiment

You can form images, of the sun or moon out of doors, or of the ceiling lights indoors, if you hold an opaque paper with a pencil sized hole in it so light falls through the hole onto a white piece of paper. You can even form an indoor image of the whole view outdoors if you make the room very, very dark, and just let light in from outside through pencil sized holes in pieces of construction paper. These images are all inverted from top to bottom and from left to right. So, if a person or a car moves outside, you can see the moving object going the wrong way upside down on a thin white piece of paper held a few inches away from the hole that lets in the light.

On the back corner of the bus, I mounted pieces of heavy paper with holes cut in them of various shapes. The images formed on a piece of paper a few feet away were all crescent shaped during the partial eclipse before and after the sun was all covered by the moon. If the paper was close, the images matched the shapes of the holes. Holes in envelope with mirrors in them did not world as well as those through which the sun shone directly.

We arranged to have the school bus parked with the driver's side toward the sun, and we covered the windows on that side with brown paper, to protect those inside from looking at the sun during the eclipse. We also roped off the shadow of the bus on the ground and placed adults around just inside the shadow of the bus to keep careless children from wandering out where they might accidentally see the partially eclipsed sun with unprotected eyes.

Some people wondered what was so dangerous about looking at the eclipse since most people look up at the sun itself once in a while.

It was reported in all the Hawaii newspapers that during previous eclipses several persons had lost the sight of their eyes or had their eyes badly damaged during the partial phases of an eclipse. The reason is that, in looking at the full sun your eyes are protected by an instinctive reaction to turn away.

However, during eclipse, there is not enough light to cause you to turn your eyes away automatically, but the part of the sun still showing is still just as bright as before, and it can painlessly burn a crescent-shaped image in the retina of your eyeball in just a few seconds. You can't stand to watch the full sun for more than a second, but you can watch the partially eclipsed sun long enough to damage your eyes.

The one eclipse experiment I didn't think of trying until too late was to burn a crescent spot on a piece of cardboard using a magnifying glass. When the sun is not eclipsed at all, a round spot can be burned that way, forming a brown or black image of the sun. Of course, you might also set a card or paper on fire that way and burn it all up.

Active Volcanoes

Two volcanoes on the "Pacific Rim of Fire," one in Japan and one in the Philippines, exploded huge clouds of dust and ashes into the air and sent mud slides and lava flowing down their sides, killing dozens and displacing thousands. The floor of the Pacific Ocean is made of huge net plates which glide slowly along, (about one inch a year). Where the plates separate, fresh lava comes up under the ocean to form a ridge. Where plates go underneath other plates, it forms trenches, earthquakes, and volcanoes. Along the whole rim of the Pacific Ocean, the sea floor plates move under one another forming the "Rim of Fire," and earthquakes.

In Hawaii, however, Kiluea Volcano has been quietly erupting millions of tons of lava for several years without stopping. A map of the Pacific shows a long chain of islands including Kanai, Oahu, Mololrai, Maui, and Hawaii, that were built from lava (the most common product) of Hawaiian volcanoes, and ashes (from relatively rare explosions). The small islands and sea mounts to the northwest of these large islands are also part of the same chain.

The present scientific theory is that they were all formed from lava coming from just one "hot spot" underneath the North Pacific plate as it crept slowly toward the northwest. The highest islands are the last two, Maui and Hawaii, because they have been the least worn down by wind and rain. The most worn down are the sea mounts and net islands at the northwest end of the chain. It is difficult to thinly that they must have once had huge mountains lilts the two newest ones.

Two years ago my wire and I saw Kilauea Volcano's lava flowing on the surface of the land, inching its way across a parking lot toward a house that had been a Visitors Center in the Hawaii Volcanoes National Park. Fire fighters were hosing down the hot lava with water to try to harden the surface enough to males it go in another direction. However, the next morning's paper showed a picture of the Visitora Center burning. The lava had reached it during the night.

This summer, the lava had made a tube, as a 15-mile long flow of lava to the sea hardened on the top but kept flowing underneath. Three of our sons walked out across a mile of the hardened lava flow watch the red-hot lava come out of the tube and plunge into the ocean. (I had a bum knee and decided not to take that walk.) A cloud of steam arose and frequently blocked their view of the lava, as the hot lava was being turned into black sand by the much colder ocean water.

We all walked in the glistening black sand that had washed up, forming a beach several miles away, and our two grandsons made a black sand castle, which was soon washed away by big waves--too big for people to swim at that beautiful new black sand beach. An older one is now all covered with new lava.

The Big Island is still getting bigger on the southeast shore as lava builds layer on layer and pours out into the sea But one of our sons and his friend also walled down into Waipio Valley on the northeast shore, where rain falls almost constantly and is washing away the very old lava rock, after first disintegrating it into red mud. So the Big Island is getting smaller there. Someday, when the North Pacific Plate has moved Hawaii away from the hot spot, will this island, too, all wash away like the others? What else moves l. a year? Some children grew 1 " this summer, I'll bet! --JE

Afterthoughts

Books and magazines that mentioned Hanauma Bay must have contributed to its overflow of tourists. (One day, we tried to take our friends there, and the parking lot was full at 9 am. The guard wouldn't let us in.) Does this newsletter, by mentioning the clear water off Ha'anapali help increase the number of tourists who go there? Will a big increase in tourists eventually mane the clear Ha'anapali water murky?

Teachers!

Don't forget to send in your pupils' questions! And send in your subscriptions, so you can find out in the next issue, what all these children's summer questions were. And send comments on things in this newsletter--and more answers!

FrEdMail

The Apple IIe computer, called UIUCED, has been checked over during the summer. A Debugs was found that blocked it's output of QUEST messages. That bug has been fixed, so we hope all goes well this year for those of you connected to FrEdMail. Let us know if there's any trouble. --J. Easley

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