About SkyG
SkyG answers one question: what's in the sky tonight? It's a stargazing guide
for beginners — moon phases computed live, seasonal highlights that never go stale, and practical
advice for finding dark skies.
Methodology: how the moon math works
Every moon phase and date on SkyG is computed, not copied. The algorithm is a
low-precision lunar theory (in the tradition of Paul Schlyter's widely used implementation):
- Solve Kepler's equation for both the Sun and the Moon to get their true
ecliptic longitudes for the given date — no mean-month shortcut.
- Apply the principal perturbation terms (evection, variation, yearly equation,
and others) that nudge the Moon off a perfect ellipse.
- Compute the Sun–Earth–Moon elongation angle; that angle divided into the full
circle gives the phase: 0 = new, 0.5 = full.
- Illumination follows from the phase angle: (1 − cos(2π × phase)) / 2.
New and full moons are found by scanning for the instants the phase crosses 0 and 0.5, refined
by bisection. We checked all 13 full moons of 2026 against published schedules (Astronomy magazine,
Farmer's Almanac): every computed instant falls within 6 minutes of the published
time, on the correct UTC calendar date. Calendar dates on this site are shown in
UTC; observers in the Americas often see the full moon on the previous evening.
What we deliberately don't publish
- Planet positions. Planets shift nightly; a fixed table would mislead within days.
We say so on the homepage instead of faking it.
- Moonrise/moonset times. These depend on your exact location. A planetarium app
computes them correctly for where you stand.
- Location darkness ratings. Light pollution varies street by street; we teach the
principles instead of inventing scores.
Who makes SkyG
SkyG is published by Studio Fungwa — contact:
thcdna@icloud.com. Follow along:
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