well, and the sun will be launched into 700 million year career as a red giant. "The red giant sun will wreak havoc on the solar system". Mercury, and possibly Venus, will be engulfed and vaporized by the sun's outer layers. The rocky surface of the Earth will melt. Even Pluto and other objects in the Kuiper Berlt will eventually warm above the freezing point. At its brightest, the sun's radius will swell to 1 astronomical unit (AU), as wide as the present Earth-sun distance. During its red giant phases, the sun will lose 45 percent of its mass to a strong outflowing wind. This mass will cause the orbits of the surviving planets to expand. Eventually, the sun will eject its outer layers as a planetary nebular and a white dwarf remnant will be exposed. This remaining white dwarf will exert less of a gravitational pull of the remaining planets. Earth's final orbit will expand to 1.7 AU, and every terrestrial year will drag on for 1,100 days. Many asteroids, especially those near the inner edge of the main asteroid belt, will end up in unstable orbits and will either crash into a planet or be ejected into the interstellar space. Galactic MillenniumAccording to the authors, Earth is now in its 46th galactic year, and the galaxy is between 100 and 150 galactic years old. The celebration of the Galactic Millennium, when the universe is 100 billion years old, will involve a very different kind of a universe. The human race will most likely not exist by then. The spiral structure of the galaxy will be gone. Earth will be a frozen cinder. The sun will become a frigid sphere of degenerate carbon. This is how the authors imagine the scene on Earth on the eve of the Galactic Millennium: "The white dwarf sun is several thousand miles across and subtends only a pinpoint in Earth's sky. The sun has long since crystallized and its surface has cooled to a frigid 63 K, roughly the temperature of liquid nitrogen. This steady temperatu...
