If there is a "donut-shaped" earth, what kind of world is it there?

Is there any possibility of having other shapes without being caught by the common sense that "the shape of the celestial body is round"? It seems that the proposition that was considered by astronomers for a long time. As if to challenge such a proposition "Donut shaped earthAttempts to verify what kind of world is spreading from existence of scientific knowledge are carried out.

Andart: Torus-Earth

He is an anthropologist at Oxford UniversityAnders · SandbergDr. his own blog "AndartFor "Donut earth" we are examining gravity, sunshine hours, climate and so on.

Poles and Equator
There are two "poles" of the North Pole and the South Pole on the Earth. Also, "equator" is running on the circumference equidistant from the North Pole and South Pole. However, in the celestial bodies on the donut, there are no poles and equators like the Earth. So Dr. Sandberg calls the light blue circle in the belly part of the illustration below, "pole", the red part of the illustration "outer equator", from the pole inside the hole of the donut etc. I will call the circumference of the distance "inner equator".

Donut and hoop
Even if we say "donut shape" exactly, its shape is various. Therefore, as a "donut earth", Dr. Sandberg has a "Donut" type which is almost the same volume as the Earth and has a smaller hole size and a gravity distribution close to the Earth but six times the volume of the Earth "Hoop (Hoop) type" that we have, we are verifying each.

The radius of the donut type is 1305 kilometers, the radius from the center to the outside (outer equator) is 16,333 kilometers, the surface area is 1.8 times the earth's 1.8 times the area of ​​820 million square kilometers, the hoop type has a hole radius of 1 It is assumed that the radius from the center to the outside is 10,937 kilometers and the surface area is 4.9 million square kilometers which is 4.9 times the size of the earth.

Gravitational acceleration
On the spherical Earth the gravity on the ground surface is almost uniform. However, on the donut earth the appearance changes steadily. The figure below shows the gravity distribution of the donut type. The extreme part is the mostGravitational accelerationOn the contrary, the inner and outer equator parts have small gravitational acceleration. In other words, on the donut earth the gravity is smaller in the equator both inside and outside, and the gravity becomes bigger as you approach the pole.

It is the speed necessary to launch a satellite from the ground surface of the donut earth and fly away from the gravity of the donut earth and to the infinity of the universeEscape speed (second space velocity)It is also measured. In the donut type, the escape speed in the direction perpendicular to the hole of the donut from the outer equator is 11.4 km / sec, and the escape speed in the horizontal direction (east-west direction) with the donut hole is 4.9 kilometers per second.

The gravity distribution of the hoop type which spreads out the hole of the donut is like this. You can see that the gravitational acceleration of the inner equator is larger than that of the donut type.

Sunshine hours
The sunshine time also varies depending on the latitude and even the spherical Earth, depending on the season. So Dr. Sandberg told us about the donut earth as well as the EarthEarth's axisWe are verifying the distribution of sunshine hours for each season with the setting which is tilted about 23 degrees.

On the donut earth, in the summer and winter season, in a wide rangeWhite nightOccurred. Unlike the Earth where you can see White nights only in a limited area near the poles, the sun will not sink in a wider area.

The figure below shows the length of the donut type sunshine hours in color. Most areas in the summer are in the white night condition, but in winter the sunshine hours are largely reduced in most areas.

It is such a hoop type. In the inner equator, it can be confirmed that sunshine hours are longer in winter than in spring and autumn. This is a phenomenon unique to the donut earth, where light comes in from the donut hole. By the diffraction of light, in the spring and autumn, it should be able to observe a beautiful sky which is very reddish in some areas.

Donut earth issatelliteAs to whether or not we can have "moon" as a matter of necessity, analysis using a computer is required strictly, but Dr. Sandberg seems to think that the possibility is very small.

Of course it is assumed that a donut-shaped object does not exist in the natural world, but if a donut earth exists somewhere in the universe, it is different from the earth in terms of gravity, climate and season everything - a wonderful world that tickles adventure "Dr. Sandberg says.

in Science, Posted by darkhorse_log