Courtesy of EarthSky
A Clear Voice for Science
Tonight, the waxing gibbous moon shines in front of the constellation Taurus the Bull. Unfortunately, the big, bright moon will wash out most of the constellation’s stars. Despite the moonlit glare, you may note Taurus’ brightest star, Aldebaran, to the right of the moon this evening, and Elnath, Taurus’ second brightest star, to the left of the moon.
For the second time this month, the moon and the Pioneer 10 spacecraft will meet up in front of Taurus. Because the moon will move eastward relative to Pioneer 10 and the background stars throughout the night, the moon will align with Pioneer 10 in the wee hours tomorrow (Wednesday, December 30). Keep in mind that the moon resides only a little over one light-second from Earth, whereas Pioneer 10 lies in the hinterlands of the solar system at some 13.5 light-hours away.
Pioneer 10 is on a trajectory that is taking this spacecraft out of the solar system and into interstellar space. Presently, Pioneer 10 is traveling at a swift 27,000 miles per hour. Even at this speed, it would take Pioneer 10 about 25,000 years to travel one light-year. When you consider that the star Elnath is 130 light-years away, Pioneer 10 won’t reach this realm of the galaxy for well over 3 million years!
Written by Bruce McClure