Gnomon: 24 Solar Terms

Before clocks divided hours into digital numbers, humanity looked to the gnomon—a simple vertical pillar casting light and shadow upon the earth to understand the turning of the year. Gnomon brings this ancient cosmological instrument to modern iOS. Built for mindfulness, astronomical curiosity, and quiet reflection, it reveals the 24 Solar Terms and 72 micro-seasons through the purity of light. KEY FEATURES • Pure Astronomical Precision: Powered by an offline, deterministic VSOP87 planetary engine. Pinpoints the exact cosmic instant the Sun crosses every 15° celestial longitude—shared simultaneously worldwide, translated to your local meridian. • Living Solar-Noon Gnomon: Watch the noon shadow lengthen toward the December Solstice and shrink toward the June Solstice. Scrub through the year with smooth gestures to witness Earth’s tilt reflected in pure geometry. • 72 Micro-Seasons (Hou): Nature changes every five days. Discover poetic observations of swallows arriving, peach trees blossoming, and the first frost settling, paired with gentle seasonal rituals for daily life. • Dual Meridian Anchors: Switch effortlessly between your current device time zone and the historical origin of solar measurement (Taosi / Luoyang, 34.6° N). Explore worldwide observatories across hemispheres without needing invasive GPS tracking. • Wabi-Sabi Aesthetics & Haptic Craft: Designed with celadon porcelain textures, rice-paper warmth, and tactile haptic feedback. A quiet sanctuary on your Home Screen.