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It weebles and it wobbles but it won't fall down.
July 5, 2010 10:16 PM   Subscribe

Year On Earth breaks it down, explaining the complicated mechanics involved in trying to determine how long a year really is, why seasons and ice ages happen, and how not all years are created equal.
posted by loquacious (22 comments total) 22 users marked this as a favorite

 
Do the Earth's magnetic poles influence the geographic poles or the tilt of the Earth's axis?
posted by infinitewindow at 10:31 PM on July 5, 2010


I hope this isn't just some elaborate way of denying climate change...

Also, between this and the "Big Bang, Big Boom" video, it's a heck of a day to visit Metafilter while doing acid!

I'm really kind of freaking out at this point.
I'm so alone in this world.

posted by hincandenza at 10:56 PM on July 5, 2010 [2 favorites]


It seems to me like it's the other way around -- the magnetic field is a byproduct of the fact that the planet spins about an axis and has a molten iron outer core. The fact that the two poles don't quite line up is a consequence of the distribution of iron not being perfectly homogeneous.
posted by Rhomboid at 10:58 PM on July 5, 2010


Do the Earth's magnetic poles influence the geographic poles or the tilt of the Earth's axis?

IANAAP, but I'm going to take an educated guess and say no, and if it would it would be negligible or a value close to zero.

However, if the magnetic poles are caused by the shifting or rotation of, say, our molten iron core and/or mantle - if masses large enough are moving around in there, or if they have a different rotational velocity than the crust and lithosphere, then that might influence the tilt of the axis of rotation of the earth the same way a raw egg doesn't spin as well as a solid hard-boiled egg.

Which is an interesting question. Does the core spin at a different rate than the lithosphere? Does it ever flip-flop or behave in chaotic or emergent ways like gyroscopes and spinning tops sometimes do? Is the molten part of our planets core responsible for the precession of the rotational axis?

Another interesting question is if the giant impact that theoretically created our Moon related to our wobble, orbital eccentricity and precession?

Did you know our core may be a georeactor and that may be why it's still hot and molten down there while slightly smaller planets seem to be much less volcanic with more solid cores?
posted by loquacious at 11:06 PM on July 5, 2010


Edit: However, if the shifting magnetic poles are caused by... etc. But the magnetic field isn't strong enough and there aren't masses large enough near by to really mess with the much larger forces involved with this much mass spinning like a wobbly top.

I only suggest there may be negligible forces from the interaction of the magnetosphere with the solar wind. The magnetosphere could be considered a rather large solar sail, but one with several very large and heavy anchors - mass of the earth, orbital velocity around the sun, etc.

If the magnetosphere moves around and changes relative shape and orientation due to the shifting poles and if the magnetosphere acts a bit like a sail, and if that sail changes shape - then there may be (again, negligible) influence on the axis of rotation, precession and other velocities and values.
posted by loquacious at 11:13 PM on July 5, 2010


dizzy. so dizzy.
posted by sleslie at 11:13 PM on July 5, 2010


The nerd in me loves this video.
The rest of me wants to strangle the narrator and his uptalking.
posted by aloiv2 at 11:14 PM on July 5, 2010 [7 favorites]


No wonder it was no fun having the job of predicting important religious days in 3500BC. Imagine the ate-the-canary smile on the first person with that job who realized that the Sun had 'farthest north' and 'farthest south' points.

No wonder, too, that the people with that job had to invent something fun to do to keep them occupied ... like make money on the side predicting people's fate by the stars.
posted by Twang at 12:04 AM on July 6, 2010


hincandenza I hope this isn't just some elaborate way of denying climate change...

I doubt it, since it's specifically all about long-time climate cycles. You probably mean human-influenced climate change though, and on the scales the video shows, that's only been feasible for approximately an eyeblink.

Life-influenced climate change is indisputable (by non-idiots) since life changes the albedo and the atmosphere (including the ocean, which is the lower layer of the atmosphere) and probably the continents too, but I don't know whether we know if the activities of life tend to exacerbate or moderate climate variation due to planetary motion. Carbon dioxide producing and consuming organisms will die off in excessive cold or heat, but on the other hand the heating and cooling changes would generally be slow enough to allow for evolutionary adaptation.

Anyway I don't see how the greater effect of the motion of the Earth on its climate does anything to deny the fact that we humans also affect the climate. We affect it a lot faster, and even if we can only make the temperature a little bit hotter or a little bit colder or let out a little bit more oil onto the ocean and land, that's still enough to cause a lot of harm to small-scale, short-time plants and animals, like ourselves.
posted by aeschenkarnos at 12:23 AM on July 6, 2010 [1 favorite]


The nerd in me loves this video.
The rest of me wants to strangle the narrator and his uptalking.


Thank you for that. My subconscious was telling me there was something off about the narrator's speech, but I couldn't put my finger on it. Uptalking is exactly it.
posted by zardoz at 12:26 AM on July 6, 2010 [1 favorite]


Hey, I'M on that planet!

Love me some space. Also love shootin' annoying narrators in the face.
posted by pyrex at 3:25 AM on July 6, 2010


...the seasons that occur on the farr side of the orbit are significantly longer in durrration... damn all these beautiful girrrls, they only wanna do you durrr...

What is uptalking and is there a filter for it? Because this guy's voice drives me crazy. I've muted the rest so I'm just learning by looking now (i.e. not learning).
posted by doublehappy at 3:56 AM on July 6, 2010 [1 favorite]


Needs autotune.

Also, tropical years rule, other years drool.
posted by gubo at 4:03 AM on July 6, 2010


Y'all are probably aware, but Earth's orbital deviations are greatly exaggerated in the visuals here. Our eccentricity is something like .016 (0 being a perfect circle), so we're pretty damn close to circular. If we had an orbit like they show here we'd all die every six months.
posted by echo target at 7:16 AM on July 6, 2010 [2 favorites]


If we had an orbit like they show here we'd all die every six months.

So you're saying we'd all become zombies? Or vampires?
posted by blue_beetle at 8:13 AM on July 6, 2010


Y'all are probably aware, but Earth's orbital deviations are greatly exaggerated in the visuals here.

I wasn't aware, but I knew something was off. The fluctuations shown in the video and apparent instability of the system freaked me out more than they should have. I thought it was a great informative piece but I couldn't shake this weird feeling of terror in the pit of my stomach. Thanks for the reassurance that this isn't really what the planet's path looks like.

Even on a mostly steady orbital path, the thought of our planet hurtling wildly through space at 66,000 mph makes my heart race when I think about it. I mean, I guess it's worked pretty well for us for, uh, basically forever. But when I see it visualized in a YouTube video... HOLY CRAP. THAT'S US ON THERE.
posted by The Winsome Parker Lewis at 9:05 AM on July 6, 2010


Great teaching video. It not only showed the common stuff, and even the 26,000 year axial precession, but then tied the 41,000-year tilt 'wobble' -and- the 100,000-year orbital-plane wobble to ice-age measurements.

A huge amount of careful work went into that little masterpiece. Move over, WGBH!
posted by Twang at 11:53 AM on July 6, 2010


Uptalking is exactly it.

No it's not. His intonation does rise dramatically near the end of each sentence, but then it drops before the "period." Uptalk is when each sentence sounds like a question. See here.
posted by Dr. Send at 12:42 PM on July 6, 2010 [1 favorite]


I was too busy nerding out on the information to even notice the slight case of uptalking, but I'm easily distracted.
posted by loquacious at 6:46 PM on July 6, 2010


It has always seemed kind of cool that our system spins around the sun nearly perpendicular to the plane of the galaxy.
posted by wobh at 10:32 PM on July 6, 2010


@wobh: Scroll down on this page to where it says "Why the Milky Way is "sideways" in the night sky" and be amazed. (More here)
posted by Twang at 12:54 AM on July 10, 2010


@wobh: But don't be amazed for too long ... (1) (2)
posted by Twang at 1:27 AM on July 10, 2010


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