In a study published earlier this year in the journal Icarus, Carruba's team analyzed the orbital evolution of the 20 known Venus co-orbital asteroids. Their simulations showed that three of these ...

Asteroids around Venus, shown in the background above during a 2012 transit, are difficult to track because they fall inside Earth's orbit and are obscured by the sun's glare.

Once it enters into its orbit around the sun on Christmas Eve, Parker—which is around the size of a small car—is estimated to be traveling at around 430,000 miles per hour, according to NASA.

Only one of the known Venus co-orbital asteroids follows a nearly circular orbit; the others move on more elongated paths that sometimes bring them closer to Earth, making them easier to detect ...