1. Dec 12, 2007

### Tarynosaurus

In my environmental science class, someone brought up this theory that was being looked at. The general idea was that the earth's axis would one day have zero tilt, and so for extremely extended periods part of the earth would point towards the sun, and part would point away. I'm no good at physics, really, but I'd like to try to find out about this. Problem is, I don't remember what it was called, even.

But the guy in class seemed to think some people believe it might be valid. I'm very interested, and would pretty much give you a play-doh replica of my soul* if you would help me out.

*\$300 for s/h, of course

2. Dec 12, 2007

### Chris Hillman

You mean to say your friend claims that some dude somewhere sez the axis of rotation of the Earth will one day lie within the the plane of its orbit around the Sun? Do you recall whether you friend said just when he thinks said dude expects this to happen? Not in the next few hundred million years, right? So nothing that will affect humans.

But semi-seriously: whatever you half-heard about, I am pretty sure it has nothing to do with the kind of theory discussed in "Beyond the Standard Model". I guess you either misheard something about the Digital Orrery and its successor , the Supercomputer Toolkit (special purpose computers built to predict the future of the solar system over the next few hundred million years) or else (gawk) some really really cranky $\zeta$ caliber wrong-as-wrong-can-be type stuff which the PF rules don't permit to be discussed here, since we don't want PF to become the kind of endless Fellini-fest which you can find on UseNet.

Last edited: Dec 12, 2007
3. Dec 12, 2007

### sysreset

The Earth's axial tilt varies between 22 and 24.5 degrees over a repeating 41,000 year cycle. Some discussions have correlated this cycle to cyclic glaciation (ice ages). I am not aware of any data suggesting a future axis of zero.

Zero tilt would not result in any part of the earth pointing at the sun, but seasons would go away.

A 90 degree tilt, however, would cause one pole to point to the sun for a while, but 180 days later, that same pole would point away from the sun. So then virtually everywhere on the planet a single day would last an earth-year. (That is the situation on Uranus, where there happens to be an axial tilt of 98 degrees, and a day on a Uranus pole lasts 84 earth-years)

Last edited: Dec 13, 2007
4. Dec 13, 2007

### Tarynosaurus

sysreset--the second, the 90 degree tilt, is what they were talking about, I think. But I think they were saying it wasn't predicted to ever happen when it would concern us, but that some people were playing with the idea.

Hmm... This is all very interesting. I like to learn about unimportant things.I will run around a bit until I find what I'm looking for. Thank you both so much :)

5. Dec 13, 2007

### Coin

If you're really curious about this incorrect-axis stuff: I haven't read it myself, and I don't know if its conclusions are entirely mainstream, but I hear the book "Rare Earth" has some discussion of what would happen on planets with unusual axes of rotation with respect to their stellar bodies.

6. Dec 13, 2007

### LURCH

It sounds more like you heard part of the discussion on Earth becoming "Tidaly locked" ni the very distant future. At any point in the discussion, did you hear any mention of H.G. Well's The Time Machine?

If the Sun don't burn out first, there would come a time 100's of millions of years from now, when the Earth will orbit with one side always facing the sun.

7. Dec 13, 2007

### chemisttree

I've seen a show titled "If We Had No Moon" where this phenomenon is discussed. Apparently, the moon stabilizes the earth's axis tilt. What happens when the moon moves sufficiently far away from the earth to stabilize the axis orientation could be what your classmate refers to.
http://shopping.discovery.com/product-52214.html

8. Dec 13, 2007

### LURCH

Based on the blueb that show sounds like a really bad source of information. They say that...
The Moon is indeed moving away from the Earth due to tidal forces, but only untill those forces equalize (and the Earth becomes tidally locked with the Moon as the Moon is with it). It's not going to keep moving away forever. And hijacking Europa?! Everyone knows Europa has way too good of security for that.

9. Dec 15, 2007

### dotman

Like Tim Robbins says in the Austin Powers movie, when they're contemplating nuking the moon-- Would you miss it?

It would be nice to not worry about new moon weekends for deep space observing all the time. Of course, there may be some problem with destruction of ecosystems which depend on tides, but I digress...

10. Dec 15, 2007

### Kurdt

Staff Emeritus
I think LURCH hit the nail on the head. You've probably been informed about tidal locking of the Earth. There is no chance of this happening any time soon however.