Terrestrial and Lunar Phases at Impact

The image below shows the phase of the Moon as seen from the Earth at the projected time of impact, 11:30 UTC on October 9, 2009. The impact will occur very near the lunar south pole. The impact plume should rise off the southern cusp, where the illuminated face of the comes to an apparent point at the southern extreme of the Moon (see the circled area on the image below). The plume of debris could rise off the limb of the Moon, into the sunlight, and, become illuminated against the dark background of space. The plume should be big enough and bright enough to see in 10 to 12-inch telescopes. However, we do not anticipate it being visible in binoculars or to the unaided eye.

The image below shows the terrestrial landmasses that will be facing the Moon at the projected time of impact. This is the view of the Earth as seen from the lunar south pole at the time of impact. If your observing location is visible in this view of the Earth, that means that the Moon will be in the sky for you at the time of impact. If your location is to the east of the areas shown below, the Moon will have set at your location before impact occurs. If your location is to the west of the areas shown below, impact occurs before moonrise at your location.

The image below again shows the view of the Earth as seen from the lunar south pole at the time of impact. Unlike the image above, we now show which portions of the Earth facing the Moon will be in daylight and which will see the Moon in a dark sky. This is important since plume will not be bright enough to see in daylight. Those areas on the right sde of the image below are lit and will experience impact during daylight hours. The areas on the left part of the image are in darkness, and will see impact in the night sky. Note that impact occurs near sunrise on the East Coast of North America. For much of the Central Time Zone in North America, impact will occur during morning twilight. Using desk-top planetarium software on your computer can provide detailed observing conditions for your specific location.