On October 24, an explosion from a comet named 17P/Holmes somewhere in between Jupiter and Neptune created a dust cloud that is now larger than the sun itself. The cloud forms a sort of atmosphere that travels with the comet, called a “coma”. In the picture above, you can see an image of Saturn shown for scale in the bottom right corner. Also, if you look closely, you can see the original “snowball” of the comet as a white spot just to the upper left of the center. Comet Holmes originated in the Kuiper Belt beyond Saturn but its orbit is due to the gravitational effect from Jupiter. For now, the comet poses no threat to Earth, but as it loses mass it will eventually be drawn closer toward the sun and could strike one of the inner planets thousands of years from now.
And if that doesn’t give you enough perspective about your relative insignificance, try this: a brief animation showing the relative size of various astronomical bodies beginning with Earth and winding up with the largest star presently known to astronomy.
Or, if you’d prefer to stay a little closer to home, the BBC reports that scientists have concluded that the Moon is relatively rare among planetary satellites for being formed through a planetary collision. Astronomers say that as they are better able to analyze photos of distant star systems, they are not finding many dust rings or debris to indicate large collisions, indicating that most moons are simply captured objects.
