Beam me to Planet Gore !
Posted on 02/12/2008 3:58:13 AM PST by raybbr
The Earth's orbital behaviors are responsible for more than just presenting us with a leap year every four years. According to Michael E. Wysession, Ph.D., associate professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, parameters such as planetary gravitational attractions, the Earth's elliptical orbit around the sun and the degree of tilt of our planet's axis with respect to its path around the sun, have implications for climate change and the advent of ice ages.
People often think of orbits as circular, but they're not that smooth and simple. They are often a less-than-perfect eccentric circle.
"All planets travel in an ellipse around the sun, but the shape of that ellipse oscillates," he explains. "When the Earth's orbit is more elliptical, the planet spends more time farther away from the sun, and the Earth gets less sunlight over the course of the year. These periods of more-elliptical orbits are separated by about 100,000 years. Ice ages occur about every 100,000 years, and they line up exactly with this change in the Earth's elliptical shape."
The purpose of the leap year is to keep our artificial calendars aligned with what the Earth actually does in its orbit around the sun and to ensure that roughly at noon on the winter solstice (Dec. 21) each year, the same point on the Earth is tilted toward the sun.
As in much of nature, the process is both neat and messy.
Wandering solstice
While we are accustomed to thinking that the Earth takes 365 days to go around the sun, it actually takes about 365.25 days. Thus, every four years the quarter days add up to one whole day. If the quarter days were unaccounted for, the solstice would wander away from its Dec. 21 date over time.
"Earth's 24 hour day is a transient thing," Wysession says. "It actually takes 23 hours, 56 minutes and four seconds to make one revolution around its axis — that is, to go all the way around so that the stars will appear in the same point in the sky day after day.
"However, during that time, the Earth also has moved one more day along its orbit around the sun, so it actually has to spin a little bit more for the sun to arrive back in the same place in the sky. This amount of time is three minutes and 56 seconds, which makes the 24 hours."
However, Wysession notes that our time units — 60 seconds, 60 minutes, 24 hours — would mean nothing had humans evolved 100 million years earlier or later because the Earth spun much faster then, and today, like aging baby boomers, it is slowing down.
Extreme seasons in the future
Despite what many people believe, seasons on Earth are not determined by the nearness of the northern and summer hemispheres to the sun.
"Seasons occur because in January, for instance, the North Pole points away from the sun, so the southern hemisphere gets more direct sunlight," Wysession says. "Six months later, that will be reversed. In terms of climate change, this has an impact because land heats up much more quickly than water, five times more quickly. The northern hemisphere has most of the land on Earth; the southern has most of the water. On January 3 or 4 (it varies) the Earth is at its closest point to the sun (the perihelion), but because water heats up so slowly, it doesn't make as much difference in temperature in the southern hemisphere as it otherwise might.
"In the northern hemisphere summer, despite the Earth being farther away from the sun, land heats up much more quickly than the southern hemisphere's water, and heats up about the same amount consistently. The two hemispheres end up buffering the climate swing, producing less severe winters than we would have otherwise."
Stick around, though, if you like extremes. Wysession says that in the future, the Earth will be farther away from the sun in winter and closer to it in the summer, causing more severe temperature swings in these two seasons. This will happen about 12,000 years from now.
"Orbital parameters of Earth, the sun and moon and the planets have great effects on ice ages and other climatic changes," he says. "Those major events are driven by very small changes in the planetary orbital functions."
Source: Washington University in St. Louis
globullwarming ping
Yeah but it’s clearly the actions of mankind and our destructive presence on the pristine and otherwise perfect planet that have caused this wobbly orbit. Clearly.
Yeah, fat Al should sit down, he's rocking the planet.
Global warming is Earth’s fault.
Clearly it’s all the obese people on the Earth slowing down the rotation. We need to tax Oreo cookies and French Fries to make people skinny again so the Earth can rotate at the proper speed.
McCain’s fault.
We’ve got 3 presidential candidates who will change all of this. They told us so.
Milankovitch cycles
Make everyone jog to the west for 10 minutes or so... that should speed things up :)
It would be nice if they had reported what point of that oscillatory cycle we are presently on.
No doubt...
Before internal combustion engines, the Earth’s orbit around the sun was a perfect circle. Just ask Al.
NO NO NO NO NO!!!!
Global warming is caused by humans... evil humans.
Haven’t you listened to a WORD the prophet Algore has said?
"Branch Algorian leader, Albert Gore continues to preach to us....
“It would be nice if they had reported what point of that oscillatory cycle we are presently on.”
The last ice age was at its coldest about 12000 years ago. Therefore we’d be about 88,000 years until the next truely major ice age. The next hottest part of the cycle would be in about 38,000 years.
As we are coming off an ice age in the upswing toward the hottest part of the cycle we are experiencing long term global warming, but spread out over 38,000 years this is not detectable year to year. Some years, even decades, are likely be colder than previous as it is not a smooth neat clean cycle.
Hey hey hey, it’s Faaaaaaaaat Albert!
I thought that the years seemed to be getting shorter.
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