I’m not worried I have a portable heater 
Galaxies? Solar systems, you mean?
There’s this common notion that infrared light specifically is a form of heat, but really, all frequencies of light behave the same way. Any object above absolute zero (which is to say, any object at all) will emit light with a frequency proportional to its temperature (actually, a spread of frequencies around that). And anything that absorbs light, of any frequency, will heat up as a result. The only reason that we associate infrared particularly with heat is that most warm objects we’re familiar with (animals, fire, etc.) have a temperature such that the light they emit is mostly infrared. But the Sun is hotter than animals or most fires, so its peak frequency of emission is higher, in visible light.
We’d have to move.
After 5 billion years, if we can’t fill a galaxy, we ain’t trying.
Move to the tropics. 
I notice there’s a link to the actual story at the bottom of the page.
Owls will deafen us with their incessant hooting.
Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet’s core would equal the heat that the Earth radiates into space, explains David Stevenson, a professor of planetary science at the California Institute of Technology.
Although some microorganisms living in the Earth’s crust would survive, the majority of life would enjoy only a brief post-sun existence. Photosynthesis would halt immediately, and most plants would die in a few weeks. Large trees, however, could survive for several decades, thanks to slow metabolism and substantial sugar stores. With the food chain’s bottom tier knocked out, most animals would die off quickly, but scavengers picking over the dead remains could last until the cold killed them.
Humans could live in submarines in the deepest and warmest parts of the ocean, but a more attractive option might be nuclear- or geothermal-powered habitats. One good place to camp out: Iceland. The island nation already heats 87 percent of its homes using geothermal energy, and, says astronomy professor Eric Blackman of the University of Rochester, people could continue harnessing volcanic heat for hundreds of years.
I would imagine the tubeworms that thrive around volcanic vents at the bottom of the sea would survive until the deep sea froze.
Why would it? It seems to me we would just continue on in a straight line, much like cutting the string on a tetherball.
If the Sun just disappeared, then presumably we go into some complex orbit around the other planets, particularly Jupiter. I suspect there would be a possibility of colliding with some other planet, if the initial position was right, in which case,
(1) any remaining life would end at that point, and
(2) the Earth would take a bit longer to cool down.
The answer depends on what, exactly, happens to the Sun or the Earth.
If we get flung off into interstellar space, the exact details would depend on how fast the Earth was moving away from the Sun. We might even move toward it and then away. In that case, it might get hotter at first, then colder.
If the Sun goes out the way we think it eventually will, it would get much hotter on Earth. The Sun, like all Main Sequence stars that fuse hydrogen into helium, is gradually getting brighter as it ages. In about a billion years, well before it reaches the red giant stage, it will be hot enough to boil away Earth’s oceans.
If, somehow, all the fusion reactions inside the Sun were to suddenly stop, and something prevented them from restarting (I think this was what the missile fired into the star in Star Trek: Generations was supposed to do), the Sun would keep shining for about 10[sup]7[/sup] years. Photons that get created by fusion in the core of the Sun don’t come out right away. The core is so dense that they bounce around for about 10[sup]7[/sup] years on average before coming out. People who observe neutrinos from the Sun would know right away that something had happened, but we’d still get light from the Sun for another 10 million years. I don’t know of any way this could actually happen under the laws of physics as we understand them.
This can’t happen. Visible light and heat (infrared radiation) are produced by the same process of nuclear fusion in the core of the Sun. You lose one, you lose both.
There probably would be some earthquakes. The Sun produces tides on the Earth (smaller than those produced by the Moon). As the Earth adjusted to the loss of those tides, there would be quakes. How bad they would be would probably depend on how quickly we were moving away from the Sun. Most likely, the Moon gets ejected away from us into interstellar space, but it’s possible that the Moon could collide with the Earth.
Huh? You lost me there. How would changes in ocean tides produce earthquakes? Does the movement of ocean water affect faultlines?
It’s not just ocean tides-- There are rock tides, too. They’re not nearly as noticeable, since rock doesn’t flow as easily as water, but they’re there.
Tidal forces are most visible in their effects on the ocean, but they act on Earth’s crust, as well.
How extraordinary!
I thought of that very story when I read the OP.
I only had partial memories of it, and now with your welcome link, I have the whole reprinted story to read.
Thanks, These are my own pants!
The 10[SUP]7[/SUP] years estimate for the random walk of photons from the core to the surface of the Sun is a pernicious error that has been much repeated. The actual estimate of the time for a photon created in the core to reach the surface of the Sun is between 10,000 and 190,000 years, based on a weighted 2D random walk Monte Carlo simulation for solar density. The 10My number is apparently based on a mean solar density rather than an accurate model of the density at different radii, which gives an unduly short run length.
If the mass and gravity field of the Sun suddenly disappeared, there would be significant effects as the lack of tidal forces (due to the gradient of the Sun’s gravity from one side of the planet to the other) was released. Although the Moon has more influence over tidal activity, the relaxation of the Earth’s crust would undoubtedly cause earthquakes and other seismic activity. The Earth-Moon system itself would stay together with only minor perturbation, but all of the planets and other Sun-orbiting objects would proceed along a course tangent to their orbit at the time of release. The likelihood of two planets colliding is so tiny as to be neglected. The influence of these bodies on each other would be negligible for any practical purpose, i.e. the Earth would not end up in orbit of Jupiter.
Stranger
sigh Some people lack ambition.
Humans are pretty resilient but we would all eventually die. Even big aircraft carriers with nuclear reactors and food for several months sooner or later it will all come down to food. The cold will kill a lot of people but their are enough people in bunkers/submarines that the food I think will be what actually kills the last person
What about folks living in Iceland and growing food in greenhouses using grow-lights powered by geothermal power stations?