An artist's illustration of asteroids flying by Earth.Peter Carril/ESA An asteroid has been trailing Earth around the sun since 100 BC, astronomers estimate. The space rock at first appears to be another moon, but it's actually orbiting the sun and not Earth. That makes this asteroid a "quasi-moon" or "fake moon." An asteroid has been following Earth around the sun for the last two millennia, and astronomers just noticed it.Scientists first discovered the space rock, called 2023 FW13, in March using the Pan-STARRS observatory in Hawaii.At first glance, the asteroid seemed to be orbiting our planet, which would make it another moon.But this tailgating asteroid is actually orbiting the sun, the space news website Sky & Telescope reported.