What About Meteors?

Background: Dr. Art's Guide to Planet Earth, pages 10-11. Utah State Earth Systems Core: Standard 3600-08: Students will investigate the universe and Earth's place in that system. Objective 01: Research and describe scientific theories on the origin and structure of the universe. Background: Dr. Art says that Earth is essentially a closed system for matter. This was not true in Earth's early history when it first formed though a process of collision and aggregation. Even after it reached its present size, the young solar system had much more debris crashing into its planets and moons. How about the last three billion years when much smaller amounts of material have been impacting our planet? Dr. Art wrote, "the total amount of matter that has entered the Earth system during the past three billion years is less than 0.00001% of Earth's total mass." We will give you the information you need to make this calculation. Try it yourself. Then compare your math with Dr. Art's. We think he might have made a small mistake in his original calculation. Information that you need: Annual inflow of material: 300 tons per day (Scientific American, July, 1999, page 44) Mass of Earth: 6 times 1024 kilograms (kg) Conversion factors for tons and kilograms: 1 ton = 2,000 pounds 1 pound = 2.2 kg Check out Dr. Art's Math... Appendix/Further Explorations: As the sun gets older, it continues to get hotter. Sometime in the next 1 to 5 billion years, scientists predict it will get so hot that it will vaporize our planet. At that time, Earth will again be a very open system for matter. The book and website will need a major revision at that time! When the solar system was very young and Earth first formed, the sun was weaker than today. It gave out about 25% less energy than it does now. If today's sun gave out 25% less energy, Earth would be a totally frozen ball. We have evidence that the early Earth was not a frozen ball. This situation has been called the Faint Sun Paradox. We know that Earth's early atmosphere was very different than today. Most Earth Systems scientists believe that the early Earth atmosphere had more greenhouse gases than today and these gases kept Earth warm despite the weaker solar energy inflow.