Phase 2 of 8 A stretch, not a moment

The Waxing Crescent

A thin lit sliver, growing. In the northern hemisphere the lit edge is on the right; south of the equator it is on the left.

Where to look: Rises mid-morning and sets a few hours after the Sun — the low evening crescent in the west, and the reason 'new moon' and 'first sighting' mean different things to different calendars.

This is the phase that starts months. A lunar calendar begins when somebody sees this crescent, which is why the start of Ramadan can differ by a day between countries that are looking at the same sky through different amounts of cloud. It is also the best phase for earthshine: the unlit part of the disc glows faintly, lit by sunlight bounced off Earth.

Commonly muddled: The horns point away from the Sun, always. If a drawing has them pointing the wrong way, the drawing is wrong.

#009ObservingPoint binoculars at the line between light and dark. That's where the Moon stops being a disc and becomes a landscape.Along the terminator the Sun sits near the lunar horizon, so crater rims cast long shadows and mountain peaks catch…NASA Moon observing

#033ObservingOn a thin crescent you can often see the whole disc faintly glowing. That's Earth, lighting the Moon's night.When we see a slim crescent, an astronaut on the Moon would see a nearly full Earth, four times wider than our Moon…NASA Moon observing

#075ObservingThe first quarter moon rises around noon. Roughly half of all the Moon's time above the horizon is spent in a blue sky, and almost nobody looks up.Only the full moon keeps strictly to the night, rising at sunset and setting at sunrise. Every other phase shares…U.S. Naval Observatory

#078ObservingMajor observatories schedule their whole year around the Moon. The nights near new moon are called dark time, and astronomers fight over them.Telescope committees split the calendar into bright, grey and dark time by lunar phase. Faint galaxies and distant…Observatory time-allocation practice (ESO…

#081ObservingA crescent's horns always point directly away from the Sun. It is a compass, and it is how you catch a fake moon in a painting.The lit edge faces the Sun, so the line joining the two tips is square to the Sun's direction, which tells you…NASA Moon observing

#082ObservingCrescent-spotting is a competitive sport. The youngest moon ever caught by naked eye was under sixteen hours old.As the crescent thins, mountains along the limb break it into beads and then swallow it entirely, the Danjon limit…Danjon (1932); observer records, Sky &…

#083Earth & tidesThat faint glow filling in the crescent's dark side is a measurement. Track it for years and it tells you how reflective Earth has become.Earthshine is sunlight bounced off Earth onto the Moon and back to us, so its brightness follows Earth's albedo…Danjon (1928); Big Bear Solar Observatory…

#084ObservingNear the equator the crescent lies on its back like a bowl. In Scotland it stands upright like a C. Nothing has tilted but you.The lit side always points at the Sun; what changes is the angle the Sun's path makes with your horizon. Near the…U.S. Naval Observatory

#093Earth & tidesA purely lunar year is about eleven days short of a solar one, so Ramadan drifts backwards through the calendar and works its way round every season in about thirty-three years.Twelve lunations come to roughly 354.37 days against the solar year's 365.24. The Islamic calendar keeps the Moon…Umm al-Qura calendar; 12 × 29.530588 days…

#147ObservingWhen the Moon passes in front of a star the star does not fade, it vanishes — instantly, because there is no air up there to blur the edge.The disappearance takes a fraction of a second and is startling the first time you see it. Timing occultations was…International Occultation Timing Association

#180Strange but trueFrom the Moon, Earth is about four times wider than the Moon looks from here and roughly forty times brighter, and it goes through phases opposite to ours.When we have a new moon, they have a full Earth, which is why the dark part of a young crescent glows: it is lit by…NASA Moon facts

#192Strange but trueTurkey, Pakistan, Tunisia, Algeria, Malaysia, Singapore, Mauritania, Azerbaijan and several others fly a crescent, and Nepal flies both a moon and a sun.The crescent predates Islam by a long way — it was a symbol of Byzantium, on coins, centuries before the Ottomans…Constitution of Nepal, Schedule 1; standard…

The Waxing Crescent

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The Waxing Crescent

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