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Where’s the moon? Waxing gibbous

The moon looks bright and nearly full. Full moon will happen on January 12, 2017 at 11:34 UTC. If you’re in the Americas, your fullest-looking moon will come on the night of January 11.

January 8, 2017 waxing gibbous moon via Lunar 101-Moon Book in Toronto, Canada.

A waxing gibbous moon appears high in the east at sunset. It’s more than half-lighted, but less than full.

That’s another way of saying that a waxing gibbous moon phase falls between a first quarter moon and a full moon. Next full moon comes on January 12, 2017 at 11:34 UTC; translate to your timezone). That’s early in the morning according to clocks in the Americas; if that’s where you are, the moon will be fullest for you on the night of January 11.

Relative to a new moon – which is more or less between the Earth and sun, located near the sun along our line of sight – a waxing gibbous moon has moved in its orbit so that it’s now relatively far from the sun in our sky.

A waxing gibbous moon rises during the hours between noon and sunset. It sets in the wee hours after midnight.

Compare this photo by Deirdre Horan in Dublin, Ireland to the one above. This photo was taken at 1:30 a.m. on January 9, 2017. The 2 photos show how – if you catch the moon very late at night – the orientation of its features with respect to your horizon will be different than if you catch it earlier in the evening.

People often see a waxing gibbous moon in the afternoon, shortly after moonrise, while it’s ascending in the east as the sun is descending in the west. It’s easy to see a waxing gibbous moon in the daytime because, at this phase of the moon, a large fraction of the moon’s day side is facing our way.

Thus a waxing gibbous moon is more noticeable in the sky than a crescent moon, with only a slim fraction of the lunar day side visible. Also, a waxing gibbous moon is far from the sun on the sky’s dome, so the sun’s glare isn’t hiding it from view.

Any moon that appears more than half lighted but less than full is called a gibbous moon. The word gibbous comes from a root word that means hump-backed. A gibbous moon can also be a waning gibbous, in the week between full moon and last quarter moon.

Waxing gibbous moon about to set on the night of August 12-13. The golden color stems from the fact that - when we see a moon low in the sky - we're seeing it through a greater-than-usual amount of atmosphere. Photo by Peter Lowenstein.

Waxing gibbous moon about to set, late at night. The golden color stems from the fact that – when we see a moon low in the sky – we’re seeing it through a greater-than-usual thickness of Earth’s atmosphere. Photo by Peter Lowenstein.

As the moon orbits Earth, it changes phase in an orderly way. Follow these links to understand the various phases of the moon.

Four keys to understanding moon phases

Where’s the moon? Waxing crescent
Where’s the moon? First quarter
Where’s the moon? Waxing gibbous
What’s special about a full moon?
Where’s the moon? Waning gibbous
Where’s the moon? Last quarter
Where’s the moon? Waning crescent
Where’s the moon? New phase

Deborah Byrd

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