Solar Ephemeris Summary
UTC+7 (Vietnam) & UTC Reference
In Gregorian year 1991, Start of Spring (Lichun, 315 degrees solar longitude), which marks the exact beginning of the Xin Wei (Goat) Year Pillar in Four Pillars of Destiny (BaZi) and Flying Star Feng Shui, occurs on 04/02/1991 at 15:08:32 Vietnam Standard Time (UTC+7). The four cardinal astronomical points of 1991 fall on 21/03 at 10:02 for the Vernal Equinox (0°), 22/06 at 04:18 for the Summer Solstice (90°), 23/09 at 19:47 for the Autumnal Equinox (180°), and 22/12 at 15:53 for the Winter Solstice (270°). All 24 timestamps below are computed via Jean Meeus Chapter 25 solar longitude series with VSOP87 harmonic corrections.
Exact 24 Solar Terms Schedule for 1991
Sectional Terms (Jie) initiate each new Solar-Term Month Pillar in Four Pillars of Destiny (BaZi); Principal Terms (Qi) govern lunar leap-month placement.
The 72 Ecological Pentads of 1991
| Solar Term | First Pentad (Day 1-5) | Second Pentad (Day 6-10) | Third Pentad (Day 11-15) |
|---|---|---|---|
| Minor Cold (Xiaohan) | Wild geese turn back toward the north | Magpies begin building lofty nests | Pheasants call out across snowy ridges |
| Major Cold (Dahan) | Hens begin brooding early clutches | Birds of prey soar swiftly in cold wind | Thick ice seals lakes and streams |
| Start of Spring (Lichun) | East wind thaws the frozen earth | Hibernating insects stir underground | Fish rise beneath the melting ice |
| Rain Water (Yushui) | Otters offer fish along riverbanks | Wild geese return northward | Trees and grasses sprout tender buds |
| Awakening of Insects (Jingzhe) | Peach blossoms open in spring warmth | Orioles sing in the morning mist | Hawks transform into gentle cuckoos |
| Vernal Equinox (Chunfen) | Swallows return to build eaves nests | First spring thunder rolls across the sky | Early lightning illuminates the clouds |
| Pure Brightness (Qingming) | Paulownia trees burst into bloom | Field Voles yield to spring quails | First rainbows appear after rain |
| Grain Rain (Guyu) | Duckweed begins growing on clear ponds | Turtledoves preen their wings | Hoopoes perch upon mulberry branches |
| Start of Summer (Lixia) | Tree frogs croak across the paddies | Earthworms emerge from damp soil | Wild gourds climb garden trellises |
| Grain Buds (Xiaoman) | Sow thistles flourish in early summer | Fine meadow grass withers under bright sun | Early grain ripens for harvest |
| Grain in Ear (Mangzhong) | Praying mantises hatch from their cases | Shrikes call from woodland canopies | Mockingbirds fall silent at midday |
| Summer Solstice (Xiazhi) | Deer shed their winter antlers | Cicadas begin singing in tall trees | Pinellia herbs sprout in shaded soil |
| Minor Heat (Xiaoshu) | Warm summer breezes sweep the plains | Crickets shelter beside cool stone walls | Young hawks learn to hunt on high cliffs |
| Major Heat (Dashu) | Decaying grass glows with fireflies | Humid earth steams in midsummer heat | Heavy convective rains nourish the land |
| Start of Autumn (Liqiu) | Cool breezes announce early autumn | White morning dew gathers on leaves | Evening cicadas chirp in crisp air |
| End of Heat (Chushu) | Hawks hunt briskly across open fields | Heaven and earth turn brisk and solemn | Late rice grains fill and mature |
| White Dew (Bailu) | Wild geese arrive from the far north | Swallows depart for southern coasts | Flocks of birds store autumn seeds |
| Autumnal Equinox (Qiufen) | Thunder quiets and withdraws | Burrowing insects seal their winter nests | Rivers and ponds recede and clear |
| Cold Dew (Hanlu) | Wild geese settle along reed marshes | Clams and shells abound along quiet shores | Yellow chrysanthemums bloom in frost |
| Frost Descent (Shuangjiang) | Jackals store prey before deep cold | Foliage turns golden and falls | Hibernating creatures retreat underground |
| Start of Winter (Lidong) | Thin ice forms over still water | Topsoil hardens in the morning frost | Pheasants dive near coastal marshes |
| Minor Snow (Xiaoxue) | Rainbows vanish from winter skies | Heavenly Qi ascends as Earthly Qi settles | All nature seals in winter stillness |
| Major Snow (Daxue) | Mountain birds fall silent in deep cold | Tigers begin their winter mating cycle | Hardy iris shoots stir in frozen soil |
| Winter Solstice (Dongzhi) | Earthworms coil deep beneath frost | Moose shed antlers as Yang Qi returns | Underground springs begin to warm |