Look in the southwest skies in the coming days to see a spectacular conjunction of Venus, Jupiter and the Moon, which will form the vertices an isosceles triangle. The US National Aeronautics and Space Administration reports that while not very rare, the phenomenon is breathtaking. The last time it was seen worldwide was last February, and the next time will be on May 11, 2011. Venus and Jupiter are the two brightest planets visible from Earth. The best time to see them converging is right after sunset; they will appear equidistant from the new moon between November 30 and December 1. Until then, they will gradually move into alignment - and if the sky isn't clouded, the moon will suddenly appear on the horizon and rise at the perfect angle between them to create the triangle. NASA official Dr. Tony Philips predicts the two planets will appear to be so close, you could hide them behind your thumb if you outstretched your arm. On December 1, you may also be able to see a phenomenon of "Earthshine," in which a ghostly image of the full moon appears inside the bright horns of the crescent. It is also known as "the da Vinci glow" because Leonardo da Vinci was the first person to explain it: Sunlight reflected by the Earth then reflects off the moon, Phillips said, casting a sheen of light across the dark lunar terrain.