Posted on 07/22/2003 7:21:52 PM PDT by vannrox
Years Were Longer 1.3bln Years ago: Chinese ScientistsPeople who complain that there aren't enough hours in the day might have preferred to live 1.3 billion years ago.At that time, according to the latest research by a group of Chinese scientists, there were 15 hours in one day, 42 days in a month, and 13 to 14 months, or more than 540 days, in a year. The finding was obtained through a five-year systematic study of stromatolite samples, known as "stone with memory", by several researchers with the Tianjin geology and minerals research institute under the China Geological Survey Bureau. Stromatolite mainly consists of the fossil of blue algae, which,rich in chlorophyll, was the first procaryote to emerge on the earth. Blue alga also contains a special phycobilin, which includes phycoerythrin and phycocyanin. While phycoerythrin mainly absorbs green light, phycocyanin is particularly sensitive to orange light and, therefore, they jointly record the traces of daylight and moonlight in each day. As a result, well preserved blue algae fossils can also contain information about the ancient climate, geology and geography from more than one billion years ago. The stromatolite samples used during the research this time were collected from a section of Yanshan mountain in Jixian county of Tianjin city in north China, where the most complete and informative stromatolite are widely acknowledged to be preserved. According to Zhu Shixing, one of the researchers, the stromatolite of their research was formed between 2.5 billion years to 1.3 billion years ago and contains blue alga fossil as thick as 3,336 meters. Starting from 1998, Zhu and his colleagues began to collect stromatolite samples containing blue algae fossils, which were finally sliced into more than 2,000 ultra-thin pieces. Under a high-power microscope, the growth trace of blue algae can be clearly seen: in daylight, it grew upright and the growth layer was thick and transparent; while in moonlight, the blue algae grew horizontally, and the growth layer turned thin and gray.The two different traces thus make up a complete daily growth layer. Further research backed by high technologies and geomagnetism, petrosus, paleoclimatology and paleotemperature knowledge indicatethat the blue algae fossil has three rhythms, namely a daily, monthly and yearly rhythm. An in-depth study of the microstructure of the stromatolite showed that the daily rhythm is represented by the basic layer, which is made up of a gray layer 0.01 mm to 0.05 mm thick and another transparent layer 0.3 mm to 0.8 mm thick. Regularly, some 42 basic layers would form a group, which is the monthly rhythm, and some 13 to 14 groups would regularly form a band generally 2 cm to 8 cm thick, which is the yearly rhythm. According to Zhu Shixing, the research result is particularly significant in that it helps to provide time coordinates for understanding the evolution of the earth and even the entire solarsystem. The earth was formed about 4.7 billion years ago, and the speedof its rotation is believed to have gradually slowed. However, no scientific evidence proving this had previously been discovered. Another important aspect it carries is that it has laid a basic foundation for the formation of a global stromatolite timepiece model, a brand-new scientific branch pursued by both Chinese and foreign scientists. |
| People's Daily Online --- http://english.peopledaily.com.cn/ |
Correct. The Earth's orbital period is a direct result of the distance and eccentricity of its orbit, not the rotation of the planet itself.
Actually do to a continuous (very slight) loss of mass from the Sun, the orbital period of the Earth is actually decreasing over time, not increasing. However, this is an extremely tiny amount. Even over 4.5 billion years the AU which is approximately 93 million miles (mean distance from the Earth to the Sun) has changed by about 28 thousand miles (~.0003%)
Note: different parts of the Sun rotate at different rates.
Not poppy-cock.
The reason the Moon keeps one face to the Earth (Its rotation on its axis matches the period of its orbit) is it is tidally locked to the Earth. This tidal locking will eventually cause the Earth and Moon to keep one face to each other.
Here is a more in depth explanation. The total angular momentum of the earth moon system, which is spin angular momentum plus the orbital angular momentum, is constant. (The Sun plays apart also) Friction of the oceans caused by the tides is causing the Earth to slow down a tiny bit each year. This is approximately two milliseconds per century causing the moon to recede by about 4 centimeters per year. As the Earth slows down, the Moon must recede to keep the total angular momentum a constant. In other words as the spin angular momentum of the earth decreases, the lunar orbital angular momentum must increase. Here is an interesting side note. The velocity of the moon will slow down as the orbit increases.
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