NASA astronomers have simulated how alien astronomers might see our solar system. Beyond the eight planets (sorry, Pluto) of the solar system, there's a cloud of dust and odd little objects called the Kuiper Belt. The hazy cloud would be visible in the infrared part of the spectrum, and if you looked closely, you might notice a mysterious dark spot. That dark spot would give you the location of Neptune, the outermost planet. As the huge planet circles the sun, it clears out the dust from the region of the belt closest to it, creating a dark patch that could be a telltale sign that our sun has a planetary system. Check out the video for an excellent explanation of the phenomenon. [A couple of years ago, extraterrestrial hunter Richard Conn Henry called for astronomers to think more about how alien civilizations presumed to exist on somewhere else in the universe might detect the habitability of our solar system. I called this "empathetic astronomy" back then and really wish the name had stuck.] Via Physics Buzz