»

# What Time Is It Anyway? by Kathi Wagner and Sheryl Racine

If someone asked you when the sun usually rises or sets, you probably couldn't predict when it would happen unless you watched the news on TV. Many local meteorologists will tell what time they expect the sun to rise or set the next day. If you watched enough sunrises or sunsets, a pattern would start to appear and then you would soon know how much earlier or later to look for them. Do you think the sun rises or sets at the same time at places that are straight north or south of your home? Scientists believe thousands of years ago a group of stargazers built a place called Stonehenge in England to keep track of the sun and possibly other things in the sky. To do this they arranged huge stones in circles that seemed to use their placement to predict when the sun would rise on the longest day of the year. Some people believe they also placed posts in holes to predict eclipses and to keep track of the passage of the days. At that time people didn't know the earth revolved around the sun, so how would they know how many days there should be? The mystery of Stonehenge is ongoing, with so many unanswered questions like were they counting the days till a certain star shape appeared again in the sky? Or when winter would come again? Over time people learned that the earth revolves every twenty-four hours giving us what is known as a solar day. They also figured out that it takes 365 days for the earth to orbit around the sun. Because there is 360 degrees in Earth's orbit around the sun and it takes 365 days to complete this orbit, the sun's star (sideral) day and the earth's day are almost the same length. Earth is one of the few planets where these two days are approximately equal!

A quote about astronomers has been placed into a puzzle grid, cut apart, and scattered through the universe! Can you figure out where each piece goes and write the letters in the empty grid?

## The Passage of Time

One expression that best sums up fate is you have to be at the right place at the right time. That expressionreally holds true here on Earth. The earth hasn't always been the way it is now. Over four billion years ago, Earth was only a chunk of metal and rock, like Mercury is today. It took billions of years for the earth's volcanoes to fill the space around it with gases that would produce a protective atmosphere. The rains that eventually fell on the earth were made when two gases combined. This combination of gases produced H2O, which is another name for water. The H stands for hydrogen and the O for oxygen. Another gas that formed on our planet was carbon dioxide. It took more than another two billion years, but animals eventually began to appear, too. Can you believe that this world, which had been steaming, eventually started freezing? Glaciers that covered much of the world would come and go for hundreds of thousands of years. Animals that were the first ancestors of your dog walked on Earth within a few hundred million years, but humans didn't appear until many years later. In many ways this may be the best of times in the history of Earth. What will the future bring? Only time will tell.

## Try This

Keeping Track of the Weather weather

Monitoring the can be fun. You can do this by making a rain gauge out of a clear plastic pop bottlemarked in inches. You can also make a snow stick from a piece of wood or use a plastic ruler. How close are your measurements to those of the weather stations? Write down your measurements. Are they different each year?

## METEOROLOGY:

Meteorology is the study of the earth's atmosphere, usually involving activities within it such as the weather. Someone who studies meteorology is called a meteorologist.

## Try This

Cloudy with a Chance of Rain

You can learn a lot about predicting the weather by looking at the clouds. Check out a book at your public library and memorize the cloud shapes and what they mean. Keep a record of how often you were right and teach your friends this new trick.

Read More Home Sweet Home, Planet Earth
Shopping

#### THE EVERYTHING KIDS' ASTRONOMY BOOK

By Kathi Wagner and Sheryl Racine

1. Home
2. Astronomy for Kids
3. Home Sweet Home, Planet Earth
4. What Time Is It Anyway?