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104

If nuclear fusion were to suddenly stop in the centre of the Sun, then the only clear signature we would have of this is the lack of detectable neutrinos received at Earth, starting about 8 minutes after the reactions ceased. The Sun however would continue to shine for tens of millions of years at roughly its current luminosity. The power source is not "...


37

Assume that a spacecraft is instantaneously accelerated at the Earth's surface (disregarding the atmosphere for simplicity). We'll consider this from the Sun's reference frame; in other words, the Sun is stationary and the Earth is moving around it. The spacecraft is accelerated to a velocity which is precisely equal and opposite to the orbital velocity of ...


17

The launch you described is similar to that of the Parker Solar Probe launched August 2018 at 12km/s in a direction opposite Earth's orbital velocity, so it fell toward (rather than into) the Sun, in an elliptical orbit. Its speed at closest approach is expected to be greater than 200km/s


13

If an object is accelerated away from Earth fast enough that it winds up having no orbital velocity around the Sun, then it will fall radially into the Sun. It's orbital velocity that keeps the object (or the Earth itself) falling around the Sun and not into it. With zero orbital velocity, it simply falls straight down and it can't do anything else (...


7

First, the Sun will not end up as a supernova - only a star $>8$ times the mass of the Sun will end its life in that way. You also have the wrong idea about "trapped light" (photons bouncing around and gradually working their way to the surface). Photons are constantly emitted and absorbed again and don't travel very far (compared to the radius of the ...


5

The "common theory" you're reading is not about the processes that produce light in stars, it's just intended as a demonstration of the speed of light through space. When it talks about the Sun "shutting down", it's not talking about the nuclear fusion processes stopping, it means that the Sun as a whole stops shining. I'm not a physicist, but I don't think ...


5

Your understanding is correct, the shadow of a vertical stick on a level plane always points north or south at solar noon, except in the Tropics where sometimes it will not have any shadow due to the Sun being at the zenith, and at the Poles, where solar noon is undefined. The sun can also be below the horizon at solar noon: places inside a polar circle can ...


2

As stated in my answer to Would we have more than 8 minutes of light, if the sun "went out"? , the Sun would cool at roughly constant luminosity for some tens of millions of years. That means "we" would not notice anything change on human timescales (apart from the lack of neutrinos, which has no measurable effect on anything apart from the odd ...


2

There are two parts to the answer and neither has anything to do (directly) with how far away the Sun is. The first part is to consider the temperature of the Sun vs the temperature of your furnace. The amount of radiation power emitted per unit area is proportional to $T^4$ (the fourth power of temperature) and it really doesn't depend on anything else. ...


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