Sirius, the brightest star in the night sky, shines 25 times more brightly than our Sun and is a staggering 50 trillion miles (81 trillion kilometers) away, making it one of our closest stellar neighbors. What’s mind-blowing is that Sirius is actually a binary system, consisting of a massive, luminous star (Sirius A) and a faint, incredibly dense white dwarf (Sirius B), which was once a giant star that has collapsed into an object about the size of Earth. Ancient Egyptians timed their calendars