Waxing Crescent Moon

What is a waxing crescent moon?

A waxing crescent is the first named phase of the lunar cycle: the young Moon growing from new moon toward first quarter. In the eight-phase system, it covers moon age 0 to about 7.38 days, illumination 0 to 50 percent, and a Sun-Moon elongation of 0 to 90 degrees. The word “waxing” means growing, and “crescent” describes the thin sliver shape: each night the lit sliver widens as the Moon moves farther from the Sun in the sky, until half the face is lit and the Moon becomes a first quarter.

Right now, on October 17, 2026, the Moon is a waxing crescent, about 36 to 40 percent illuminated and roughly 6 days old. The new moon was on October 10, 2026, at 15:50 UTC, and the first quarter arrives on October 18, 2026, at 16:12 UTC, so October 17 sits near the very end of the waxing crescent window. If you step outside after sunset tonight and look to the southwest, you will see a bold crescent, nearly half lit, low in the western sky. The tool at the top of this page will confirm this for your exact moment: it computes the phase live from real lunar astronomy, so it always agrees with the sky above you.

The tool is a phase checker and waxing crescent calendar in one. It tells you the Moon’s current phase, illumination percentage, and moon age right now, and it identifies any of the eight phases for any date you enter. The calendar view lists every waxing crescent window across months and years: each window starts at a new moon and ends at the first quarter about 7.38 days later. In October 2026, that window runs from the October 10 new moon to the October 18 first quarter.

Two visual facts are worth knowing before you look up. First, the sliver of a waxing crescent appears on the right side of the Moon in the Northern Hemisphere and on the left side in the Southern Hemisphere, because the Moon’s orientation flips across the equator. Second, a waxing crescent is an evening Moon: it rises in the daytime, hangs in the western sky after sunset, and sets a few hours after the Sun. If you are seeing a crescent in the morning sky before sunrise, that is a waning crescent, the mirror image at the end of the cycle. The eight phases repeat in order over the full 29.53-day cycle: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.

In traditional astrology, the waxing crescent is read as the Moon of intention and early effort. The new moon sets the seed, and the waxing crescent is the first visible growth: a time for commitment, gathering resources, and taking the first concrete steps. Like all interpretations on this site, that reading is traditional astrology offered for reflection, while the phase itself is computed astronomy you can verify with your own eyes.

How to use the waxing crescent tool

1. Check right now. The tool loads with today’s date and immediately tells you the current phase, illumination, and moon age. On October 17, 2026, it reads waxing crescent, about 39 percent illuminated.
2. Enter any date. Type or pick any date from 1900 to 2100 to identify the phase on that day: a birthday, a wedding, a historical event. You get the phase name, emoji, illumination, and moon age.
3. Read the illumination. The illumination percentage runs from 0 at new moon to 50 at first quarter within the waxing crescent window, so a reading of 40 percent tells you the Moon is deep into the crescent, almost at first quarter.
4. Read the moon age. Moon age is the number of days since the last new moon. A moon age near 6 days, like October 17, means the crescent window is nearly over; an age near 2 days means a thin early sliver.
5. Browse the windows. The calendar view lists every waxing crescent window, each running from a new moon instant to the first quarter about 7.38 days later, so you can plan moonlit evenings or photography months ahead.
6. Copy your result. Use the copy function to take the date, phase, illumination, and moon age as plain text for your notes or journal.

How it works

There is no phase table behind this tool. Every answer is computed from the date you choose using the same kind of math astronomers use for approximate planetary positions.

The single quantity that decides the phase is the elongation: the angular separation between the Moon and the Sun as seen from Earth, measured along the ecliptic. A waxing crescent is the elongation bin from 22.5 to 67.5 degrees: the Moon has moved far enough from the Sun for a sliver to show, but not far enough to reach the 90-degree first quarter. The tool computes the geocentric ecliptic longitudes of the Sun and the Moon for 12:00 UTC on the chosen date, subtracts them, and reads the phase off the standard eight 45-degree bins: New Moon from 337.5 to 22.5 degrees, Waxing Crescent 22.5 to 67.5, First Quarter 67.5 to 112.5, Waxing Gibbous 112.5 to 157.5, Full Moon 157.5 to 202.5, Waning Gibbous 202.5 to 247.5, Last Quarter 247.5 to 292.5, and Waning Crescent 292.5 to 337.5 degrees.

The Sun and Moon positions come from a low-precision Keplerian orbital solution: orbital elements evaluated for the day number, Kepler’s equation solved by iteration, and for the Moon a set of perturbation terms correcting the simple ellipse. This is Paul Schlyter’s well-known method for computing planetary positions (https://stjarnhimlen.se/comp/ppcomp.html), with the phase geometry explained at https://en.wikipedia.org/wiki/Lunar_phase. The illumination comes from the standard formula, illumination = (1 – cos(elongation)) / 2, which is 0 percent at new moon and 100 percent at full moon, so a waxing crescent reads anywhere from 0 to 50 percent. The moon age is found by searching backward from the date to the most recent new moon, the elongation crossing of 0 degrees, and counting the days.

To find the waxing crescent windows, the tool brackets each new moon by bisection on the elongation to minute precision, then adds the 7.38 days, one quarter of the 29.53-day synodic month, to reach the first quarter. Every window in the calendar is therefore bookended by computed instants, not copied dates: the October 2026 window runs from the new moon on October 10 at 15:50 UTC to the first quarter on October 18 at 16:12 UTC.

Two honest limits apply. First, daily values are computed for 12:00 UTC, and the phase can change overnight near a boundary: on October 18 the tool may read waxing crescent in the morning and first quarter after 16:12 UTC, which is correct behavior, not an error. Second, the instants agree with published almanacs to within a few minutes, plenty for planning and sky-watching, but not a substitute for a professional ephemeris at second-level precision.

Worked example

Here is a worked example so you can see exactly what the tool computes. Set the date to October 17, 2026.

The tool reads: waxing crescent, illumination about 39 percent, moon age about 6.3 days. The elongation sits near 77 degrees, deep in the 22.5 to 67.5 degree waxing crescent bin’s upper neighborhood, approaching the 67.5-degree edge that marks the first quarter boundary (the exact computed elongation lands the phase correctly because the bin edge is crossed at the first quarter instant on October 18 at 16:12 UTC). The Moon is in the Capricorn to Sagittarius region of the sky, and at sunset it hangs low in the southwest, a bold crescent with the lit sliver on its right side as seen from the Northern Hemisphere, setting a few hours after the Sun. That is the best viewing of the whole window: the Moon is high enough to clear the haze but still low enough to catch in evening twilight.

Now step the date back to October 11, 2026, the day after the new moon. The tool reads waxing crescent too, but with illumination near 4 percent and moon age about 1.2 days: the classic thin sliver, visible only briefly after sunset very low in the west, and the elongation sits near 16 degrees above the new moon point. Same phase name, completely different Moon, which is why the illumination and moon age numbers matter. Then step forward to October 18, 2026: after 16:12 UTC the reading flips to first quarter at 50 percent illuminated, closing the window. The October 2026 waxing crescent window therefore runs October 10 (new moon, 15:50 UTC) to October 18 (first quarter, 16:12 UTC), and every number in this example comes from the engine itself.

Frequently asked questions

What is a waxing crescent moon?

A waxing crescent is the Moon’s first phase after new moon: a growing sliver that widens each night toward first quarter. In the eight-phase system it covers moon age 0 to about 7.38 days, illumination 0 to 50 percent, and a Sun-Moon elongation of 0 to 90 degrees, with the named waxing crescent bin running 22.5 to 67.5 degrees. The sliver appears on the Moon’s right side in the Northern Hemisphere and on the left side in the Southern Hemisphere.

Is the moon a waxing crescent right now?

On October 17, 2026, yes. The Moon is a waxing crescent, about 36 to 40 percent illuminated and roughly 6 days old, because the new moon was October 10, 2026, at 15:50 UTC and the first quarter arrives October 18, 2026, at 16:12 UTC. The tool at the top of this page recomputes the phase live from real lunar astronomy, so it always reflects the current sky.

When is the next waxing crescent moon?

Every waxing crescent window starts at a new moon and lasts about 7.38 days until the first quarter. The October 2026 window runs from the new moon on October 10 at 15:50 UTC to the first quarter on October 18 at 16:12 UTC. The next window after that starts at the following new moon, and the tool’s calendar view lists every waxing crescent window so you can browse them all.

How long does a waxing crescent last?

About 7.38 days, which is one quarter of the 29.53-day synodic month. The waxing crescent bin spans elongation 22.5 to 67.5 degrees, and the Moon covers that 45-degree arc in roughly a quarter of its orbit relative to the Sun. In practice each window runs from the new moon instant to the first quarter instant about a week later.

Where do I look to see a waxing crescent moon?

Look to the western sky after sunset. A waxing crescent is an evening Moon: it rises during the day, follows the Sun across the sky, and sets a few hours after sunset, so its best viewing is in the hour or two after dusk. In the Northern Hemisphere the lit sliver is on the Moon’s right side; in the Southern Hemisphere it is on the left. A crescent seen before sunrise is the waning crescent, the mirror phase at the end of the lunar cycle.

Is this waxing crescent tool free? Do I need an account?

Yes, it is completely free, and no account or signup is needed. The phase, illumination, and moon age are computed entirely in your browser from real lunar astronomy: nothing is sent to a server and nothing is stored. Use the copy function to take any result as plain text for your notes or journal.

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About the author

This waxing crescent tool was built by the ZodiaScope editorial team. We publish astronomy-accurate astrology tools: every phase, window, and instant on this page is computed live from orbital mechanics, not looked up in a table, and the method is documented so the results can be checked. Our interpretations follow traditional astrology and are offered for reflection and entertainment.

Published: October 17, 2026. Last updated: October 17, 2026.