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93

Life forms are made up from materials already present in Earth. Thus, increasing population would not alter the overall mass of the planet, and can't impact its orbit.


27

I live close to Lake Erie and often see scenes like in this picture. Note that the bottom of the cargo ship cannot be seen due to the curvature of the Earth.


22

A lot (to put it mildly) of elements are created in stars and supernovae. These elements then travel through space until they fall to Earth (or, to be exact, some microscopic portion of them reach us). Earth itself wouldn't exist if stars hadn't generated elements which then clumped into dust, into minerals, and so on until a big ball of matter started to ...


20

Related to the Andrea di Biagio answer. Here is a typical flight path for the Beunos Aires-Auckland route. The distance is approximately 10,300 km by the shortest route along a sphere. Direct flights are offered by Air New Zealand and take 11h40m - an average speed of 882 km/h. Looking at the map you present, the distance from Auckland to Buenos Aires looks ...


19

Mass is conserved (up to whatever small contribution nuclear decay has to the overall loss of mass). All biological matter is just created from materials from the environment (we do eat, right?). With exception of an occasional space probe, shooting stars and solar wind effects, the earth can be considered a closed system in terms of matter exchange. ...


12

How can we detect Earth's spin? Apparent motion of Sun You will have observed that the sun reappears every 24 hours. There are two common explanations for this. One of them is that the earth rotates with a period of approximately 24 hours - this is the only explanation supported by the scientific evidence. The main alternative had a rather convoluted ...


11

Foucault Pendulum is a great example. The original purpose of this experiment was to prove that earth rotates relative to the stars and not the other way around, yet nevertheless it proves that the earth rotates in a way which contradicts the "flat earth" theorem. This experiment can be easily recreated at home, if you don't live close enough to equator.


9

You need three flat Earth theorists on different continents (or otherwise well separated) all in on a (video) conference call, and have them measure the azimuth and elevation angles of the sun at the same time. The set of angles that they report will be inconsistent with their locations being on a flat disk laid out as in the map in the question. This is a ...


8

As others have said, the mass of the Earth doesn't go up because we are eating food produced on Earth. Suppose we somehow were importing really large amounts of extra-terrestrial food, now what happens? We roast. Food contains a fair amount of carbon. Carbon from extra-terrestrial food is just as much a greenhouse problem as burning fossil fuels. ...


7

The stars in our galactic neighbourhood do have a dynamical, gravitational effect on the inner workings of the solar system: They built the Oort cloud The Oort cloud is a roughly spherical cloud of icy bodies that is thought to act as a reservoir of long-period comets (and which we speculate exists to explain said comets' existence). These icy bodies ...


6

The other answers talk about some of the effects. This is a complementary answer that attempts to put a number to the force behind one of the effects - gravitational attraction. Proxima Centuri is the closest star to our solar system. It is about 4 × 1016 m away and has a mass of 2.45 × 1029 kg. The mass of Earth is about 5.97 × 1024 kg. Plugging these ...


6

I don't think that light from the stars other than Sun is of much practical use nowadays except for the classic navigation, where it's essential of course. I guess any effect comes from the limitless reach of the gravitational force, which drops with the square of the distance but grows linearly with the mass exerting the force. A star most obviously ...


6

Airplanes. Note that dozens of flights cross every ocean and the equator in all directions every day. If the Earth were a disk, it would actually be impossible to do that. For example, if the border of the disk were more or less where the borders of a planisphere are, it would be impossible to cross the Pacific. How would your friend explain how flights ...


5

Can you convince your friend that time zones are for real? If he will believe that it is nighttime in China when it is daytime in the US, then his disk theory can't be correct.


5

Plenty of others made it clear that babies aren't made out of matter from somewhere else. But if the earth's mass were to increase ten percent by magic, its orbit would not change. Its momentum—its tendency to fly off into space in a straight line—would increase by ten percent, and the counteracting force of the sun's gravity would increase by ten percent. ...


5

If you believe that anyone lives on antarctica at all, or really anywhere south of the antarctic circle, then you can use the "midnight sun" effect, which should not happen in the flat earth theory (because the sun moves around the "antarctica ring" during northern winter). Surveillance cameras will also work for this, if eyewitness accounts are not ...


3

Take an arrow which you put tangent to the earth (assume it to be a perfect sphere). Now, travel around in such a way that 1) you enclose some finite area, 2) do not rotate the arrow locally. Coming back to your starting point you will notice the following: Although you did not rotate your arrow locally, you will end up with an arrow which is rotated ...


3

If the sun is a disk (or sphere) that is a certain distance above the earth, close enough that you get it at different angles above the horizon depending on where you stand, then it has to look like a different size to different people. If it looks the same size, then you cannot explain that it's at a different height above the horizon. See this diagram: ...


3

As a former sailor I can assure you that you can see the curvature of the earth from the crow's nest - all it takes is a calm sea. Consider a light house that stands 50 meters above sea level. If you are in the crow's nest, say 25 meters above sea level), at what distance could you first spot the top of the light house on a calm day? The problem is ...


3

Gravitationally, there is little immediate effect on earth on a daily basis, though over very long periods of time, stars that pass near enough to the sun could disrupt the orbits of Oort cloud objects and send them towards the sun (and earth or other planets in our Solar System). Culturally, stars have a very big impact on our species. Religion, art, ...


3

The gravitation of the stars in our galaxy keep the solar system in it. I'm not sure whether that's important for earth or for life on earth though, but it makes for nicer night skies. Gamma ray bursts, if close enough and (im)properly oriented, affect earth. A gamma ray event from a "soft gamma repeater", SGR 1900+14, is known to have affected earth's ...


2

Perhaps the least convenient but the most direct is go to the Moon and observe the Earth. The (average) length of day as measured by timing stellar transit to stellar transit, sidereal day, differs by 4 seconds from the length of day defined by timing noon on one day to noon on the next day, solar day. A satellite launched East requires less energy to ...


2

Whenever you have a spherical shell with homogeneous mass, any object outside of it will feel a radial attraction, while any object inside will feel no gravitational force at all, since all the vectors cancel out. So, try to picture Earth as a collection of shells with distinct radii and density. If the particle is positioned inside some shells, but outside ...


2

There's a lot of text here, hopefully it's not too much and makes at least a little sense. $\ddot\smile$ There are several units for gravity, depending on how you model gravity and what you're looking to calculate. Energy, in Joules ($J$); or spacetime distortion, but I don't know the units, both measure the "absolute" amount of gravity near a point, and ...


2

The reflectivity of the atmosphere, and of the surface itself, is strongly wavelength-sensitive. So while some percentage of any given wavelength is reflected -- and some percentage is absorbed rather than transmitted, the variation over wavelength is what leads to the somewhat misleading statement you refer to. Here's an example of atmospheric absorption, ...


2

Try https://www.insecam.org/ .Take a flat map of earth and make them go to the cities and watch the light and the online clocks. Nothing but a sphere fits the data. If the sun is going around a disk there would be night almost simultaneously over the flat disk, whereas the cameras will show progressive changes and night for half of their flat earth.


2

Have them pull out their smart phone and open up Google maps and touch the icon to zoom to their current location. Remind them that what they just did is only made possible by satellites in orbit using clocks specially tuned according to general relativity to maintain accurate synchronization with clocks on the surface (i.e., in the smart phone). Welcome ...


1

My somewhat naive (but understandable) contribution. Begin with flat Euclidean space ( Earth with zero gravity ) Switch on the g force. Spacetime curves and the [euclidean] radius of earth diminish 9 mm. ( earth is sucked in down the gravitational pit ) This diminish earths area on the order of A=2Rr (2 * 10^7 * 10^-2 = 10^5 sqm) The [euclidean] volume of ...


1

If this particle was travelling towards earth, where would its rest state be? If the particle is moving fast enough, the answer is nowhere. The particle will gain speed as it approaches the center of the Earth. The speed will be rather high at the point of closest approach to the center. The particle will lose speed as it moves away from the center of ...


1

If you compare the Earth-Sun distance in the summer and in the winter, you will notice that it differs by only about 4%. Given that the radiation strength of the Sun is proportional to 1/distance^2, the radiation intensity is roughly 8% STRONGER in the WINTER (on the northern hemisphere) than in the summer. But the distance to the Sun is not the only ...



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