Amir Ijaz, age 11, of Winnipeg, Manitoba, Canada, for his question:
HOW MUCH DOES THE EARTH WEIGH?
By using careful mathematical calculations, scientists are able to tell us that the earth weighs 6.6 sextillion tons. That number is written with 20 zeros following the number 66.
The earth is a giant sized ball covered with rock, water and soil. It is one of nine planets that travel through space around the sun. The sun is a star and only one of billions that make up a galaxy called the Milky Way.
Just to make you feel even smaller, you must realize that our Milky Way is only one of billions of other galaxies that make up the universe.
If you were to drill a hole from the North Pole to the South Pole, you would travel just a bit less than 8,000 miles. The earth's polar circumference, or the distance around the planet from one pole to the other and back again, is 24,859.82 miles. The equatorial curcumference, or the distance around the earth along the equator, is 24,901.55 miles.
Even though the earth is just a speck in space when compared to the billions of galaxies that make up the universe, it looks like a mighty large place when you're standing on it.
The planet that weighs 6.6 sextillion tons has a total surface area of 196,940,400 square miles. Almost 58 million square miles, or about 30 percent of the total surface area, is covered with land. About 70 percent is covered with water.
A total of 99 percent of the earth's air or atmosphere is less than 100 miles above the surface, although particles of the atmosphere extend 1,000 miles upward.
The highest spot of land on the earth's surface is the 29,028 foot mark set by Mt. Everest. The lowest spot of land is 1,299 feet below sea level, in the Dead Sea.
The average depth of the earth's oceans is 12,450 feet. The deepest spot is found in the Challenger Deep, in the Pacific Ocean southwest of Guam. Here, the water is 36,198 feet deep.
Scientists tell us that the earth is approximately 4.5 billion years old.
The earth is just exactly the right distance from the sun to support both animal and plant life. If it were too close to the sun, the earth would be too hot for living things. And if it were too far from the sun, it would be too cold for anything to live.
Most living things must also have water and a gas called oxygen, or they will die. The earth has a lot of both.
The earth is always moving. It spins much like a top as it travels around the sun. It takes the earth one day to spin around once, and one year for the earth to travel once around the sun.
The study of the earth is called geology and scientists who study the earth are called geologists.