Railroad
Routinely Derailed
The following is an excerpt from a Live Science article posted in the YAHOO! News.
Ice Ages Blamed on Tilted Earth<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
fficeffice" /><o></o>
Wed Mar 30,12:42 PM ET<o></o>
<!-- Yahoo TimeStamp: 1112204558 --><!-- timestamp 1112204558 64756 secs stale 28800 secs -->Michael Schirber
LiveScience Staff Writer
LiveScience.com <o></o>
In the past million years, the Earth experienced a major ice age about every 100,000 years. Scientists have several theories to explain this glacial cycle, but new research suggests the primary driving force is all in how the planet leans.<o></o>
<!-- ult -->The Earth's rotation axis is not perpendicular to the plane in which it orbits the Sun. It's offset by 23.5 degrees. This tilt, or obliquity, explains why we have seasons and why places above the Arctic Circle have 24-hour darkness in winter and constant sunlight in the summer.<o></o>
But the angle is not constant - it is currently decreasing from a maximum of 24 degrees towards a minimum of 22.5 degrees. This variation goes in a 40,000-year cycle.<o></o>
Peter Huybers of Woods Hole Oceanographic Institution and Carl Wunsch of the Massachusetts Institute of Technology have compared the timing of the tilt variations with that of the last seven ice ages. They found that the ends of those periods - called glacial terminations - corresponded to times of greatest tilt. <o></o>
"The apparent reason for this is that the annual average sunlight in the higher latitudes is greater when the tilt is at maximum," Huybers told LiveScience in a telephone interview.
Ice Ages Blamed on Tilted Earth<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
fficeffice" /><o></o>Wed Mar 30,12:42 PM ET<o
></o><!-- Yahoo TimeStamp: 1112204558 --><!-- timestamp 1112204558 64756 secs stale 28800 secs -->Michael Schirber
LiveScience Staff Writer
LiveScience.com <o
></o>In the past million years, the Earth experienced a major ice age about every 100,000 years. Scientists have several theories to explain this glacial cycle, but new research suggests the primary driving force is all in how the planet leans.<o
></o><!-- ult -->The Earth's rotation axis is not perpendicular to the plane in which it orbits the Sun. It's offset by 23.5 degrees. This tilt, or obliquity, explains why we have seasons and why places above the Arctic Circle have 24-hour darkness in winter and constant sunlight in the summer.<o
></o>But the angle is not constant - it is currently decreasing from a maximum of 24 degrees towards a minimum of 22.5 degrees. This variation goes in a 40,000-year cycle.<o
></o>Peter Huybers of Woods Hole Oceanographic Institution and Carl Wunsch of the Massachusetts Institute of Technology have compared the timing of the tilt variations with that of the last seven ice ages. They found that the ends of those periods - called glacial terminations - corresponded to times of greatest tilt. <o
></o>"The apparent reason for this is that the annual average sunlight in the higher latitudes is greater when the tilt is at maximum," Huybers told LiveScience in a telephone interview.
