Don't Let The Sun Go Brown - Bryan James
A series of threats to Earth, wake people up, to the fact that they might not be immortal as a species, after all.
Geoff was probably as innocent as anybody could be, under the circumstances. Not being too worried, personally, when Betelgeuse, a red giant star in its death-throws, caused a whole bunch of comets to threaten Earth on a regular cycle, but he became very distressed when he was the victim of a body swap.
Zapped down to the Oort cloud, he finds his computer skills are in demand, but his problems don't stop there.
He can't get back home, gets snatched by aliens, and that's just the start of the adventure.
Visits alien worlds, and gets to see all the spectacles of the solar system on the trip home, at 200,000 MPH, while moons of certain planets start to misbehave, but how will they slow down in time so that they don't end up falling into the sun, as ash?