kottke.org posts about Earth
A list of ten things that you didn’t know about the earth. My favorite one, by far:
But what if you did dig a hole through the Earth and jump in? What would happen?
Well, you’d die (see below). But if you had some magic material coating the walls of your 13,000 km deep well, you’d have quite a trip. You’d accelerate all the way down to the center, taking about 20 minutes to get there. Then, when you passed the center, you’d start falling up for another 20 minutes, slowing the whole way. You’d just reach the surface, then you’d fall again. Assuming you evacuated the air and compensated for Coriolis forces, you’d repeat the trip over and over again, much to your enjoyment and/or terror. Actually, this would go on forever, with you bouncing up and down. I hope you remember to pack a lunch.
Note that as you fell, you accelerate all the way down, but the acceleration itself would decrease as you fell: there is less mass between you and the center of the Earth as you head down, so the acceleration due to gravity decreases as you approach the center. However, the speed with which you pass the center is considerable: about 7.7 km/sec (5 miles/second).
Fast forward to the year 2483 and we’ll probably all be using such holes to quickly travel through the earth. Spain to New Zealand in 42 minutes! New York to the middle of the Indian Ocean? 42 minutes! I also recall reading somewhere that the tunnels don’t need to run through the middle of the earth. You don’t get the free fall effect, but with the proper contraption (mag-lev tunnel train?) you’ll be pulled through the tunnel at a great speed. Does this ring anyone’s bell?
Update: A bell has rung. The tunnels described above are called chord tunnels and the travel time through the earth in a frictionless chord tunnel is always 42 minutes, even if the tunnel is only a few hundred miles long or so (say from New York to Detroit). (thx, mike)
Update: In this short Nova clip, Neil deGrasse Tyson “demonstrates” a trip through the center of the earth. (thx, michael)
Flat-earthers are people who believe, here in the 21st century, that the Earth is flat. (Believers in a round earth are called globularists.)
And what about the fact that no one has ever fallen off the edge of our supposedly disc-shaped world? Mr McIntyre laughs. “This is perhaps one of the most commonly asked questions,” he says. “A cursory examination of a flat earth map fairly well explains the reason — the North Pole is central, and Antarctica comprises the entire circumference of the Earth. Circumnavigation is a case of travelling in a very broad circle across the surface of the Earth.”
If, like me, you have questions about how the Earth could possibly be flat, some of them are answered in the Flat Earth FAQ.
Q: “What about the stars, sun and moon and other planets? Are they flat too? What are they made of?”
A: The sun and moon, each 32 miles in diameter, circle Earth at a height of 3000 miles at its equator, located midway between the North Pole and the ice wall. Each functions similar to a “spotlight,” with the sun radiating “hot light,” the moon “cold light.” As they are spotlights, they only give light out over a certain are which explains why some parts of the Earth are dark when others are light. Their apparent rising and setting are caused by optical illusions. In the “accelerating upwards” model, the stars, sun and moon are also accelerating upwards. The stars are about as far as San Francisco is from Boston. (3100 miles)
BTW, the “ice wall” is what separates the edge of the earth’s disc with outer space or whatever ether or monsters are beyond the earth. We know the wall as Antarctica. I call shenanigans on all this…it’s gotta be a hoax. Nobody’s this ignorant, right? Please?
An amazing collection of abstract satellite photos, demonstrating the “impressionist, cubist and pointillist” side of the earth’s landscape.
The images you see below were taken at the turn of the Millennium, when NASA’s scientists had a brilliant idea: to scan through 400,000 images taken by the Landsat 7 satellite and display only the most the most beautiful. A handful of the best were painstakingly chosen and then displayed at the Library of Congress in 2000.
You must see these. Bonus: all the images are available in wallpaper size for your computer desktop.
This site lets you track the International Space Station, the Space Shuttle (when in orbit), and all sorts of other satellites in relation to their position over the earth with a familiar Google Maps interface. Very cool.
On the origin of the Earth’s moon and how our planet would be different if we didn’t have a moon.
The Moon has been a stabilizing factor for the axis of rotation of the Earth. If you look at Mars, for instance, that planet has wobbled quite dramatically on its axis over time due to the gravitational influence of all the other planets in the solar system. Because of this obliquity change, the ice that is now at the poles on Mars would sometimes drift to the equator. But the Earth’s moon has helped stabilize our planet so that its axis of rotation stays in the same direction. For this reason, we had much less climatic change than if the Earth had been alone. And this has changed the way life evolved on Earth, allowing for the emergence of more complex multi-cellular organisms compared to a planet where drastic climatic change would allow only small, robust organisms to survive.
Earthrise and earthset movies made by Kaguya, a Japanese spacecraft currently orbiting the moon. Also available here at a higher quality. I’m hoping these are available in HD at some point.
This New Yorker article on light pollution makes mention of the Bortle Dark-Sky Scale, which is a measure of how bright the stars are in a particular part of the sky.
In Galileo’s time, nighttime skies all over the world would have merited the darkest Bortle ranking, Class 1. Today, the sky above New York City is Class 9, at the other extreme of the scale, and American suburban skies are typically Class 5, 6, or 7. The very darkest places in the continental United States today are almost never darker than Class 2, and are increasingly threatened. For someone standing on the North Rim of the Grand Canyon on a moonless night, the brightest feature of the sky is not the Milky Way but the glow of Las Vegas, a hundred and seventy-five miles away. To see skies truly comparable to those which Galileo knew, you would have to travel to such places as the Australian outback and the mountains of Peru.
The World Without Us looks like an interesting read:
If a virulent virus — or even the Rapture — depopulated Earth overnight, how long before all trace of humankind vanished? […] Days after our disappearance, pumps keeping Manhattan’s subways dry would fail, tunnels would flood, soil under streets would sluice away and the foundations of towering skyscrapers built to last for centuries would start to crumble.
Here’s a similar article from New Scientist from late 2006. (via mr)
Geological features called chevrons could be evidence of violent comet/asteroid impacts as recently as 1000 years ago. The chevrons are formed by massive tsunamis; scientists believe one such tsunami occurred in the Indian Ocean 4,800 years ago and was 600 feet high. These impact-caused tsunamis may also be responsible for the various flood myths found in world religions. (thx, matt)
Bob Holmes imagines an earth without people in New Scientist. “All things considered, it will only take a few tens of thousands of years at most before almost every trace of our present dominance has vanished completely. Alien visitors coming to Earth 100,000 years hence will find no obvious signs that an advanced civilisation ever lived here.”
Update: Derek Miller notes that even after human traces have vanished from earth, evidence of our civilization would remain on the moon and in space.
And if you ever need to move the Earth, here’s how you might accomplish that. “The Earth is very big, moving very fast, and therefore very difficult to stop or even slow down.”
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