Are You Scared of the Dark?
Imagine if there were no television and no radio and you knew very few people. If that wouldn't be strange enough, then the sky starts to darken, the birds head for their nests, and suddenly the sun disappears! Would you know what was happening? It's no wonder that some of the earth's early inhabitants feared that this was a sign their gods were unhappy. To be sure they would have some kind of warning before this happened again, they built temples and machines to help them predict when the next eclipse or darkening of the sun might occur. Fortunately, solar eclipses don't last long — only around seven minutes. Eclipses of the sun occur when the earth, the moon, and the sun are directly in line with each other. Even though the diameter or distance across the moon is much smaller than the diameter of the sun, the distance between the earth and the moon allows the entire surface of the sun to be hidden from sight. Any type of solar eclipse can only be seen from a small area on Earth, so observers are usually glad even to see a partial eclipse where it looks as though the moon has taken a bite out of the sun!Because an eclipse moves so quickly, a person would have to run over a thousand miles an hour just to outrun the shadow it makes as it moves across the earth.
Yes, the Earth Is Round!
Maybe you have seen an eclipse of the moon. Since they occur at night and the moon doesn't turn black, it probably wasn't as scary for the early people as a solar eclipse. Since you know what causes a solar eclipse, what do you think causes a lunar one? A lunar eclipse happens when the sun, the earth and the moon all line up together. When this happens, the earth keeps the sunlight from reaching the moon. Some of the very first astronomers decided that the earth had to be a round object when they saw the curved edge of the earth move across the face of the moon. If you would you like to see one of these rare sights, type in “eclipses & NASA” in your search box on the Internet. You will also find lists and catalogs there that will predict the dates of eclipses to come for thousands of years!
Did you know that every person who lives on Earth gets a free vacation every year? That's right — no matter how rich or how poor, each person gets a free ticket to travel more than 370 millionmiles! Where are we all going? To find out, color in all the blocks with the letters F-R-E-E T-R-I-P.
Long Nights, Short Days
Did you ever wonder why the days are longer in the summer and the nights are longer during the winter? If you live in a place where you can watch the sun set, you might try looking to see where the sun is in the sky on June 21st compared to December 21st. June 21st is known as the longest day of the year in the Northern Hemisphere. Some of the first explorers soon learned that the further north you travel, the longer the days last. Have you heard of the land of the midnight sun? This land is located near the North Pole and named this because you can still see the sun at midnight! Unlike June 21st, December 21st is the shortest day of the year. These two days are known as the summer and wintersolstices or the days when the sun seems to stand still! You might think all of this was caused by the earth rotating to the north and south, but it is actually the earth's rotation around the sun that causes these changes. Have you ever played with a toy top or a gyroscope? The center that it spins on is straight up and down. Unlike a top, the earth's center of balance is tipped over 23 degrees. This is a very good thing, because as Earth moves around the sun, part of the year the sun shines directly on the Northern Hemisphere and part of the time it shines on the Southern Hemisphere.
The next time you go camping spend a little time watching the campfire. If you watch the flames closely, you will see different colored flames that show the level of heat. Blue flames are the hottest, followed by yellow, and then red, which are cooler than blue, but still hot enough to burn. Stars like our sun are coded by colors depending on how hot they are.