Exact Answer: Till 100,000 years.
Astronomers have predicted that for at least 100,000 years from now, humans will see the Betelgeuse star explode as a supernova from the Earth.
Betelgeuse, the bright and beautiful red-colored dot on Orion’s shoulder, is one of the key identifiers of the constellation. It is the tenth-brightest star in the night sky and the second-brightest in the constellation of Orion after Rigel. Also, classified as a red supergiant of M1-2 spectral type.
Betelgeuse is one of the biggest stars that are visible to the naked eye. If it was in the center of the Solar system, then its surface would lie way beyond the Asteroid Belt. It would inundate the orbits of the four closest planets to the sun: Mercury, Venus, Earth, and Mars.
How Long Would Betelgeuse Supernova Last?
According to some speculations by some professional astronomers, 100,000 years from now, we might see the Betelgeuse star explode as a supernova from the Earth. Unfortunately, there are still doubts the reasons are also questionable. Betelgeuse is equivalent to twenty times the mass of our Sun (table below) but not clearly said that it’s headed to becoming a supernova any time soon.
Betelgeuse already spent all the hydrogen as fuel in its core and has now moved on to the new element Helium, which fuses into carbon. Presently, the core of Betelgeuse is now considerably smaller than when it had been fusing hydrogen. The more it contracted and the tremendous rise in temperature led to the star to heat up and it began fusing helium. The outer layers, with this increased radiation pressure, expanded and cooled tremendously.
Its brightness has dropped, raising concerns because of the star being out-listed from the top 10 brightest stars list. Not only is the dimming considered a suspect to the possible supernova expected but also very improbable. Otherwise, considering big stars, sometimes due to the large convective cells in the outer layer, gas clouds might form. The gas clouds might be the reason behind this dimming.
If the supernova has to happen then the star will brighten to that point where it will exceed the brightness of the full Moon, casting brilliant shadows to watch in the night sky and will be visible during the day for years.
| Heavenly Body | Radius | Mass | |
| Betelgeuse | 617.1 million km | 2.188 × 10^31 kg | |
| Sun | 696,340 km | 1.989 × 10^30 kg |
Why Would Betelgeuse Supernova Last So Long?
Betelgeuse might lie about 430 light-years from our Earth even though some of the estimates place it farther away considering the distances to red supergiant stars like Betelgeuse is likely a problem in astronomy.
Betelgeuse is way away, yet it’s one of the brightest stars visible from the Earth because it’s 100,000 times even brighter than our sun. Its enormous energy requires its fuel to be spent quickly, which reduces the gap to the end of its life. Someday, sooner or later the star will run out of its fuel and collapse under its weight. The result will be a spectacular supernova explosion. If this happens, the star will glow for a couple of weeks or even months, perhaps becoming as bright due to the full-of-the-moon, and be visible in broad daylight.
Betelgeuse is already out of its hydrogen phase because it has spent all of it as fuel in its core and has now moved on to the new fuel element Helium, which fuses into carbon. Presently, the core of Betelgeuse is now considerably smaller than when it had been fusing hydrogen. But it is not assured if Betelgeuse is presently fusing helium exclusively in its core. Considering the timescale of Helium, fusion lasts for 100,000 years but Carbon fusion lasts for hardly a few hundred. The speculated time limit might be mentioned because of this timescale.
Conclusion
Therefore, we can expect a supernova explosion of the Betelgeuse star maybe centuries later or even just a decade. But if Betelgeuse does explode later, our planet Earth is way too far for this cosmic event to harm the lives on Earth. The supernova explosion would be 642.5 light-years away from our earth approximately.
So, if the explosion has to harm us, we must be within 50 light-years close to the supernova according to astrophysicists. Betelgeuse is nearly ten times this distance. But, if the cosmic phenomenon does occur, our next generations might be able to witness it later. Astronomers must be willing to have Betelgeuse as close as it is so that they can study the star post-supernova.