The celestial wonders of April's solar eclipse and the mesmerizing dance of last weekend's aurora borealis captivated millions, yet the cosmos has an even more elusive spectacle in store. Before the year's end, the night sky will unveil an astronomical phenomenon so extraordinary that it eclipses the rarity of both these events combined. A blazingly bright event known as a nova, a light show that happens approximately once every 80 years, is expected to be visible in the coming months. "This could be a once-in-a-lifetime viewing opportunity," NASA said. An animation showing a nova of a white dwarf that is...