A weekly feature of Torah Tidbits to help clarify practical and conceptual aspects of the Jewish Calendar, thereby better fulfilling the mitzva of HaChodesh HaZeh Lachem...

The Moon does not orbit the Earth in a perfect circle. The Earth-Moon does not orbit the Sun in a perfect circle. The Earth does not rotate on its axis in the same plane that it revolves around the Sun.

As a result of the above, the distances between the Earth and the Moon and between the Earth and the Sun vary, as do the relative positions in the sky of the Sun and the Moon, as we see them from Earth. These factors, in turn, cause a full Moon, for example, to vary in apparent brightness and size.

On Wednesday, December 22nd, these "events" occurred within a rare, relatively short period of time – namely, Full Moon, perigee (the Moon's closest approach of Earth during its monthly orbit), and the Winter Solstice (when the Sun is at its lowest point in the sky at noon - in the northern hemisphere). According to some(but not all) astronomers, the Moon will appear brighter and larger than any time in the last 133 years, and will not appear so for more than another 100 years.

Because of the above and atmospheric conditions, the Moon had an especially large and prominent halo on Tuesday and Wednesday nights.