Based on the number of supernova-generated nebulae, astronomers estimate that a supernova occurs roughly once every half century in the Milky Way galaxy. The last known supernova to have occurred in our own home galaxy brightened the night skies of Johannes Kepler in 1604, a mere 32 years after Tycho's supernova (click to see image).
Recent news that Betelgeuse had started to collapse generated a great deal of speculation that this brightest star in Orion might go supernova, soon. Scientists have long predicted that it might do this in the next million years or so. But Betelgeuse might brighten up the day-time sky in our own lifetimes as a type II supernova.
The supernova will likely be harmless to life on Earth because of the star's great distance and because the pole of rotation is pointing away from Earth—sparing us the greatest portion of gamma ray emission.
Because the great distance and the fact that Betelgeuse is receding from us at about 22 km/second, the remnant will never reach Earth before dissipating into harmless gas and dust.
IK Pegasi is the closest known candidate for a future supernova, though a great deal will have to transpire before that happens. This system is a binary with a bright A8 main sequence star and a white dwarf orbiting each other every 21.7 days. In the future, when the A8 primary star runs out of hydrogen and evolves into a red giant, its outer envelope will be pulled onto the surface of the white dwarf, greatly increasing the mass of that degenerate body.
When that mass approaches the Chandrasekhar limit of about 1.44 solar masses, and if the star is a carbon-oxygen white dwarf, it will explode as a type I supernova. In the nearly million years it might take for these things to happen, IK Pegasi will have moved a few hundred light years farther away, greatly reducing any impact it will have on Earth's biosphere. And, like Betelgeuse, the future IK Pegasi remnant will not pose a hazard to our tiny planet.