Where Did the Earths Water Come From?
Earth is located within the “snow line” of the solar system, the region closest to the Sun where H2O is primarily in liquid or gaseous form, if at all. The snow line is located in the outer asteroid belt, between the orbits of Mars and Jupiter. The snow line phenomena is reflected in the water content of planets like Mercury, Venus, and Mars. Water is absent on Mercury. On Venus, H2O only exists as a trace element in the atmosphere. Mars only has a thin veneer of ice in its polar regions. In general, water is rare within the snow line. Why does Earth have so much water relative to the other inner planets? 71% of the surface is covered in the oceans, more than half of which is deeper than 3,000 meters (9,800 ft), with an approximate total volume of 1.3 billion cu km (310 million cu mi). Still, the oceans only make up 0.023% of the Earth’s total mass. There are various theories as to where all the Earth’s water came from, but several theories have fared better than the others. We know th
Outgassing by volcanos and comet strikes. When the earth ceased to be constantly bombarded by asteroids, it cooled sufficiently for oceans to form. Actually oceans (and perhaps life) formed many times, only to fall victim to asteroid strikes which would cause the oceans to boil away. When the earth cooled and the asteroid impacts ceased the atmospheric water vapor could condense into rain and the great mother of all rain storms filled the basins becoming oceans.
Has the amount of water on earth changed over the last million years or so? Today’s homework assignment is to read/skim Chapter 11, Section 1 in your text. 21 March 2007 – Lecture and discussion on Chapter 11, Section 1 “Water” followed by 10 question quiz 22 March 2007 – Video on Earth’s Catastrophic History 23 March 2007 – Complete video on Earth’s Catastrophic History and discuss 26 March 2007 – Lecture and discussion on Chapter 11, Section 2, “Water Use and Management” followed by 10 question quiz. 27 March 2007 – Class work, preview Chapter 11, Section 3 “Pollution” Complete Section Review questions 1-5, page 293. View Discovery Video “Changing Earth” 28 March 2007 – Class work complete Chapter 11 review questions 1-22 on page 293 of your text. Discuss recent article on the discovery of a new venomous snake in India and the implications to locals.
From what I understand, even though it may seem like the earth is the only planet in the solar system with water, it isn’t. New speculations have said that Mars may have more water than earth. It is just frozen. Several moons have water as well. It is possible that the water was brought to earth by a comet or it could have been there all along.
