Betelgeuse is the 11 brightest object in the night sky and the second brightest object in the Orion constellation after Rigel. The star is a red giant about 11 times more massive than the sun. If Betelgeuse had been in the same location at our sun it would have been swallowed all the inner planets and reach the current orbit of Jupiter. The star is just 10 million years old but it has evolved rapidly because of its huge mass and will soon end in a supernova within 100 thousand years. Our sun will just as Betelgeuse also become a red giant in 5 to 6 billion years and will increase its radius to reach the current orbit of the earth. But our Sun is not massive enough to become a supernova instead it will form a planetary nebula and leave behind a white dwarf as massive as the sun but much denser with a radius similar to Earth. Betelgeuse, on the other hand, will explode in a massive supernova and leave behind neutron star 1.5 times more massive than our sun.
Betelgeuse Credit: ESO/L. Calçada
Recently astronomers have discovered that Betelgeuse is getting fainter. By the end of December, it is the 23 brightest object in the night sky. This could mean that Betelgeuse is becoming a supernova, but there could be other explanations for the dimming Betelgeuse is a variable star that has increasing and decreasing cycles of luminosity.
Hypothetically if now Betelgeuse were to explode in a supernova, how will it look like? And will it be dangerous for us? Betelgeuse will become as bright as our moon and light up the night sky and it could even be visible during the day. It lasts for a couple of weeks or even months before it fades away. This would be an amazing astronomical event to observe it will be a priceless scientific possibility for astronomers to learn more about supernovas. Betelgeuse is 640 light-years from the sun and the radiation from the supernova will not affect us on that distance. If we will have the opportunity to see a supernova soon than Betelgeuse should have exploded during the 14th century.
The last time a supernova was visible was 1604 the Kepler's Supernova 20000 light-years from Earth. It was the brightest star in the sky. It was observed by Kepler and was published in the work De Stella nova. It was also reported by Chinese, Korean and Arabic sources.