(2018)
Ancient Earth Globe
71–75 of 75 posts
Re: Ancient Earth Globe
#72How much of that topology is speculation? I get that geologists can estimate the latitude of a location at a given time because of climate and chemical signals, plus some contemporary tectonic shift vectors. I don't get how paleomagnetism is reliable when the magnetic field can wander in the timespan of some thousand years. I'd expect the resulting equations to yield a multitude of solutions or even be unsolvable.
*topography. My degree was in math and topology is a branch of math but when everyone thinks I'm talking about maps :)
Just be cautious asking a cosmetologist about galaxies and star formation, you may be disappointed in the answers.
Re: Ancient Earth Globe
#73GPlates[1] is related. It has python apis[2], and a web portal[3], with assorted topographic models[4], and another interactive[5] like OP (also based on Scotese's work).
[1] https://www.gplates.org/ [2] https://www.gplates.org/docs/pygplates/pygplates_introductio... https://github.com/GPlates/gplately [3] https://portal.gplates.org/#apps-anchor [4] https://portal.gplates.org/portal/dt/ (select "Mantle Reference Frame" for a similar layout) [5] https://portal.gplates.org/cesium/?view=PaleoDEM https://www.earthbyte.org/paleodem-resource-scotese-and-wrig...
Re: Ancient Earth Globe
#74How might we better visually present a heterogeneous block of time?
Consider "today"'s coastline. Earlier today, a mere 15 kya towards Last Glacial Maximum, Florida was twice as thick, and the Boston coast was down past Long Island NY. So how do you non-deceptively show a coastline for "today"? Perhaps use such low resolution that these differences aren't visible? Use an aphysical elevation color scheme which deemphasizes water height? Use timelapse averaging (if a single frame was exposed for 100 ky, then ...)?
Years ago NASA did a global clouds-removed monthly image set. You can see the snow line advancing and retreating with the seasons. See changes in vegetation. Months look very different. What best represents the year? An average of them? The preceding year had different weather. How can the preceding decade be nicely represented? The preceding 100 y, 1 ky, 10 ky?
Clouds are a major visual component our planet. Their patterns change with seasons, with years, with climates, with topographies. How might you show this year's clouds? This decades? This 100 ky? This 1 My?
Climate. Consider the insanely desiccated Pangaean central equatorial desert. In OP, it's colored green based on height. I've seen it shown overlayed with swirls of seemingly cumulus clouds.
Science education graphics have the unfortunate property of combining some aspects done with great care, with many others done with great artistic bogosity, and students left with no way to sort what is which. How might paleoglobe visuals be improved?
Re: Ancient Earth Globe
#75Earlier quoted context omitted.
> un-provable ... plausible Your idea's first hurdle is the length of day vs the length of month. How do you keep the moon over one bulged part of Earth at all times? (it's a very different story for the moon, whose 'day' is as long as its orbit, more at [1]) Additionally, there is a solar tide at work on the oceans that is visible daily, and especially at spring and neap tides. The sun's mass drives a maximum of alm…
I wondered if it was possible at some point in the past, but I don't think so. The moon's orbit has been increasing its whole existence. It started ~25,000 km away from Earth [0], and is now at ~384,000 km. That means at some point it was at the distance for a current geosynchronous orbit, ~36,000 km. Unfortunately, when the moon was formed, the Earth's day was only 6 hours long [0], so the geosynchronous orbit was m…
It's really hard to break global hydrostatic equilibrium of a planet (in fact, that global roundness[1] is used in the IAU's definition of a planet). Any raising of bumps on the surface will tend to produce depressions elsewhere. For example, Mauna Kea depresses the level of the seabed/crust around it. Likewise, high tide at some points (in the solid earth, the oceans, or the atmosphere) are associated with low tides at other points.
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[1] You could probably toy with models of Earth-moon as a pair of Jacobi ellipsoids or piriforms (pear-shaped, thin ends inwards) but I don't see that working without a much smaller mass ratio and higher spins. Piriform bodies (at least of homogenous self-gravitating fluid, which is a good representation of the mantle) are generally unstable. Maybe that's good if you can find a path that relaxes back to a Maclaurin (oblate) spheroid for the Earth mass that doesn't also relax the (whole of the) "bump", and relaxes the moon to its weak Jacobi (scalene) spheroid.
Really speculating substantially away from what I know: maybe the "synestia" flavour(s) of the giant impact hypothes(e)s for the origin of the moon might be a path to some test simulation codes: coalesce an ellipsoidal (or as I said, piriform or even oviform) moon first and have that drive some aspects of Earth's planetary differentiation (which happens later in that (family of) model(s): https://en.wikipedia.org/wiki/Synestia>). In particular, the driving should be away from homogeneity in an attempt to escape eventual hydrostatic equilibrium for the Earth-mass which otherwise leaves you stuck with encoding surface features on the (very) thin crust and then dealing with the Mauna Kea problem above. I don't know how you could approach this idea with realistic chemistry though, which I think melts & dissolves this line of thinking.
ETA: Really wild speculation: with unrealistic chemistry, freeze out a long-term solid hourglass structure with the neck at the Earth's centre of mass, piling lots of rocks on the ends terminating just under the surface (but above the mantle) at the poles, and then have one pole always point to the moon Mass. Doesn't at all fit lots of lines of evidence in very old surface rocks, though. Also very hard to wash out tides raised by the sun.