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Moon in the Middle

June 10, 2016

A couple of bright companions flank the fat crescent Moon tonight. The brilliant planet Jupiter is to the upper left of the Moon, with the star Regulus about the same distance to the right of the Moon.

The Moon itself is approaching first quarter, when sunlight will illuminate half of the lunar hemisphere that faces Earth. So right now, the Moon is in its “waxing crescent” phase. The Sun lights up less than half of the visible Moon, but the fraction that’s in the light is getting bigger by the hour.

At first quarter, on Sunday morning, the Moon will be one-quarter of the way through its month-long cycle of phases. After first quarter, it’ll be in its “waxing gibbous” phase — more than half of the visible hemisphere will be in sunlight, with the fraction continuing to increase. The Moon will reach maximum illumination when it’s full, on June 20th.

After that, the cycle of phases will reverse. Less and less of the visible Moon will be in sunlight, so the Moon will be “waning.” First it’s waning gibbous, then it’s at last quarter, then it’s a waning crescent. The cycle comes to an end when the Moon is new — it passes between Earth and Sun, so it’s lost from view in the Sun’s glare. That’ll happen on the Fourth of July.

And a day or two after that, the Moon will pop into view as a thin crescent in the western evening sky — a waxing crescent that’s beginning the cycle all over again.

More about the Moon and Jupiter tomorrow.

Script by Damond Benningfield

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