Betelgeuse will explode someday. It lies some 430 light-years from Earth. Yet it’s already one of the brightest stars in Earth’s sky. The reason is that Betelgeuse is a supergiant star. It is intrinsically very brilliant.
Such brilliance comes at a price, however. It is one of the most famous stars in the sky because it’s due to explode someday. Betelgeuse’s enormous energy requires that the fuel be expended quickly (relatively speaking), and in fact Betelgeuse is now near the end of its lifetime.
Someday soon (astronomically speaking), it will run out of fuel, collapse under its own weight, and then rebound in a spectacular supernova explosion. When this happens, Betelgeuse will brighten enormously for a few weeks or months, perhaps as bright as the full moon and visible in broad daylight.
When will it happen? Probably not in our lifetimes. But, in fact, no one really knows. It could be tomorrow or a million years in the future.
So, Will Betelgeuse Become a Second Sun?
Short answer: no. it won’t be bright enough to appear as a second sun in our sky. Instead, anyone alive on Earth when it happens will be treated to an amazingly beautiful sight in the night sky – a very, very, very bright star (watch this video to make an idea):