Centaur Schwassmann-Wachmann 1 has a chance to get funneled into the inner solar system in the not-so-distant future. This artist’s concept shows what the comet would look like if it were 0.2 AU (19 million miles, 30 million kilometers) from Earth. Note the Moon at upper right for scale. (Credit:
University of Arizona/Heather Roper)

Astronomers have discovered an orbital region just beyond Jupiter that appears to act as a kind of gateway for some objects entering the inner solar system from