真太阳时
True Solar Time

真太阳时（True Solar Time，简称TST）是以太阳实际运行位置为基准的时间系统。当太阳到达一个地点正上方（过中天）时，真太阳时恰好为正午12:00。这与我们日常使用的钟表时间（标准时间）存在差异，因为标准时间是以时区的中央经线为基准统一设定的，而同一时区内不同经度的地点看到太阳过中天的时刻各不相同。 在八字命理学中，真太阳时具有至关重要的意义。八字的时柱（Hour Pillar）是根据出生时刻的地支时辰来确定的，而传统的十二时辰划分是基于太阳在天空中的实际位置——子时对应太阳在正北方最低点，午时对应太阳在正南方最高点。因此，要准确确定一个人的时柱，必须使用该出生地点的真太阳时，而非钟表上显示的标准时间。 举个例子：中国采用统一的北京时间（东八区，基准经线120°E），但中国幅员辽阔，最西端的新疆喀什（约75°E）与最东端的黑龙江抚远（约135°E）之间相差约60个经度，这意味着两地的真太阳时可以相差约4小时。一个在喀什出生于北京时间上午8:00的人，其真太阳时大约只有上午5:00左右——这可能导致时柱从辰时变为寅时，从而彻底改变八字的四分之一。

True Solar Time (TST) is a timekeeping system based on the actual position of the sun. When the sun reaches its highest point directly above a location (solar noon / upper meridian transit), the True Solar Time is exactly 12:00 noon. This differs from the clock time (standard time) we use daily, because standard time is set uniformly based on a time zone's central meridian, while different longitudes within the same time zone observe the sun crossing the meridian at different moments. In Bazi destiny analysis, True Solar Time holds critical importance. The Hour Pillar of the Bazi chart is determined by the Earthly Branch of the birth hour, and the traditional twelve-hour division (shi chen) is based on the sun's actual position in the sky — the Zi hour corresponds to the sun at its lowest point due north, and the Wu hour corresponds to the sun at its highest point due south. Therefore, to accurately determine a person's Hour Pillar, one must use the True Solar Time for the birth location, not the standard clock time. Consider this example: China uses a unified Beijing Time (UTC+8, reference meridian 120°E), yet China spans an enormous territory. The westernmost point of Kashgar, Xinjiang (approximately 75°E) and the easternmost point of Fuyuan, Heilongjiang (approximately 135°E) differ by about 60 degrees of longitude, meaning their True Solar Times can differ by approximately 4 hours. A person born in Kashgar at 8:00 AM Beijing Time has an actual True Solar Time of roughly 5:00 AM — which could shift the Hour Pillar from the Chen hour to the Yin hour, fundamentally altering one-quarter of the entire Bazi chart.

我们日常使用的钟表时间是一种人为规定的时间标准。为了社会运作的便利，全球被划分为24个标准时区，每个时区覆盖大约15个经度，时区内的所有地点统一使用同一个标准时间。这种制度虽然方便了交通、通讯和商业活动，但它与天文学意义上的“真实时间”之间存在着系统性的偏差。 这种偏差主要来自两个因素： 第一，经度偏差。同一时区内，你的实际位置可能偏离时区中央经线较远。地球每旋转1度经度需要4分钟，因此如果你的位置偏离中央经线7.5度（半个时区的宽度），真太阳时就会与钟表时间相差约30分钟。在像中国这样横跨多个地理时区却使用单一标准时间的国家，偏差可能更为显著。 第二，时间等差（Equation of Time）。由于地球绕太阳的轨道是椭圆形而非正圆形，加上地球自转轴与公转轨道面之间存在约23.4度的倾斜角（黄赤交角），太阳在天空中的运行速度并不均匀。这导致真太阳日（从一次太阳过中天到下一次太阳过中天的时间间隔）并不恰好等于24小时——有时略多，有时略少。这种累积效应使得在一年中的不同日期，真太阳时与平均太阳时（即钟表时间的天文基础）之间会产生最大约±16分钟的偏差。 这两个因素叠加在一起，可能使真太阳时与钟表时间之间的总偏差达到数十分钟甚至数小时。对于出生在时辰交界附近的人来说，这个差异可能足以改变时柱的判定。

The clock time we use daily is an artificially defined time standard. For the convenience of social operations, the globe is divided into 24 standard time zones, each covering approximately 15 degrees of longitude, with all locations within a zone using the same standard time. While this system facilitates transportation, communication, and commerce, it introduces a systematic deviation from the astronomical "true time." This deviation stems from two primary factors: First, the longitude offset. Within the same time zone, your actual location may be significantly displaced from the zone's central meridian. The Earth takes 4 minutes to rotate through 1 degree of longitude, so if your position deviates from the central meridian by 7.5 degrees (half a time zone's width), the True Solar Time will differ from clock time by approximately 30 minutes. In countries like China, which spans multiple geographic time zones yet uses a single standard time, the deviation can be even more pronounced. Second, the Equation of Time. Because the Earth's orbit around the sun is elliptical rather than perfectly circular, and because the Earth's rotational axis is tilted approximately 23.4 degrees relative to the orbital plane (the obliquity of the ecliptic), the sun's apparent motion across the sky is not uniform. This causes the true solar day (the interval from one solar noon to the next) to be not exactly 24 hours — sometimes slightly more, sometimes slightly less. This cumulative effect means that on different dates throughout the year, the difference between True Solar Time and Mean Solar Time (the astronomical basis for clock time) can reach a maximum of approximately plus or minus 16 minutes. When these two factors combine, the total deviation between True Solar Time and clock time can amount to tens of minutes or even several hours. For individuals born near the boundary of two traditional Chinese hours, this difference may be sufficient to change the Hour Pillar determination.

时间等差（Equation of Time）是天文学中描述真太阳时与平均太阳时之差的一个量，其数值在一年中持续变化。理解这个概念需要知道两个天文因素： 椭圆轨道效应：根据开普勒定律，地球在椭圆轨道上运行时，距太阳较近时（近日点，约在每年1月初）速度较快，距太阳较远时（远日点，约在每年7月初）速度较慢。这意味着地球在近日点附近每天需要多转一点角度才能“追上”太阳，使得真太阳日略长于24小时；反之，在远日点附近真太阳日略短于24小时。 黄赤交角效应：地球赤道面与公转轨道面之间约23.4度的夹角导致太阳在天球上的投影运动速度在一年中不均匀——在春分和秋分附近，太阳沿赤道方向的运动分量较小（因为此时太阳主要沿南北方向移动），而在夏至和冬至附近，太阳沿赤道方向的运动分量较大。 这两个效应叠加产生了时间等差的年度变化曲线。一年中有四个时间等差为零的点（大约在4月15日、6月13日、9月1日和12月25日），以及四个极值点。最大正偏差约+14分钟（出现在2月中旬），最大负偏差约-16分钟（出现在11月初）。 在八字命理的实践中，时间等差通常通过查表或公式计算。现代的八字软件和在线工具（包括我们的系统）会自动根据出生日期计算当天的时间等差值，并将其纳入真太阳时的修正计算中。

The Equation of Time is an astronomical quantity describing the difference between True Solar Time and Mean Solar Time, with its value changing continuously throughout the year. Understanding this concept requires knowledge of two astronomical factors: Elliptical Orbit Effect: According to Kepler's laws, as the Earth travels along its elliptical orbit, it moves faster when closer to the sun (perihelion, around early January) and slower when farther away (aphelion, around early July). This means that near perihelion, the Earth must rotate slightly more than 360 degrees each day to "catch up" with the sun, making the true solar day slightly longer than 24 hours. Conversely, near aphelion, the true solar day is slightly shorter than 24 hours. Obliquity Effect: The approximately 23.4-degree angle between the Earth's equatorial plane and its orbital plane causes the sun's projected motion on the celestial sphere to be non-uniform throughout the year. Near the spring and autumn equinoxes, the sun's motion component along the equatorial direction is smaller (because the sun is primarily moving in the north-south direction), while near the summer and winter solstices, the equatorial component of the sun's motion is larger. The superposition of these two effects produces the annual variation curve of the Equation of Time. There are four points during the year when the Equation of Time equals zero (approximately April 15, June 13, September 1, and December 25), and four extreme points. The maximum positive deviation is approximately +14 minutes (occurring in mid-February), and the maximum negative deviation is approximately -16 minutes (occurring in early November). In Bazi practice, the Equation of Time is typically obtained through lookup tables or formulas. Modern Bazi software and online tools — including our system — automatically calculate the Equation of Time value for the birth date and incorporate it into the True Solar Time correction calculation.

经度修正是真太阳时计算中最直观也最重要的一步。其原理很简单：地球自西向东旋转，每旋转360度需要24小时，因此每1度经度对应4分钟的时间差。 计算公式为：经度修正 = (出生地经度 - 标准时区经线) × 4分钟/度 以中国为例，北京时间的基准经线是东经120度。常见城市的经度修正如下： 上海（121.5°E）：+6分钟（比北京时间快6分钟） 北京（116.4°E）：-14.4分钟（比北京时间慢约14分钟） 成都（104.1°E）：-63.6分钟（比北京时间慢约1小时4分钟） 乌鲁木齐（87.6°E）：-129.6分钟（比北京时间慢约2小时10分钟） 哈尔滨（126.6°E）：+26.4分钟（比北京时间快约26分钟） 从这些数据可以直观地看出，经度修正的影响远大于时间等差（最大±16分钟）。对于中国西部地区的出生者，经度修正可能达到1-2小时甚至更多，这几乎必然会导致时柱的变化。 完整的真太阳时计算公式为： 真太阳时 = 钟表时间 + 经度修正 + 时间等差 在使用我们的八字计算工具时，您只需提供出生地城市或经度坐标，系统会自动完成全部修正计算。这就是为什么我们在排盘时会要求您填写出生地点——不仅是为了记录信息，更是为了确保时辰判定的准确性。

Longitude correction is the most intuitive and important step in True Solar Time calculation. The principle is straightforward: the Earth rotates from west to east, completing 360 degrees in 24 hours, so each degree of longitude corresponds to a 4-minute time difference. The formula is: Longitude Correction = (Birth Location Longitude - Standard Time Zone Meridian) x 4 minutes per degree Using China as an example, the reference meridian for Beijing Time is 120°E. The longitude corrections for common cities are: Shanghai (121.5°E): +6 minutes (6 minutes ahead of Beijing Time) Beijing (116.4°E): -14.4 minutes (approximately 14 minutes behind Beijing Time) Chengdu (104.1°E): -63.6 minutes (approximately 1 hour 4 minutes behind Beijing Time) Urumqi (87.6°E): -129.6 minutes (approximately 2 hours 10 minutes behind Beijing Time) Harbin (126.6°E): +26.4 minutes (approximately 26 minutes ahead of Beijing Time) These figures clearly illustrate that the impact of longitude correction far exceeds that of the Equation of Time (maximum of plus or minus 16 minutes). For individuals born in western China, the longitude correction can reach 1-2 hours or more, which will almost certainly cause a change in the Hour Pillar. The complete True Solar Time formula is: True Solar Time = Clock Time + Longitude Correction + Equation of Time When using our Bazi calculation tool, you only need to provide your birth city or longitude coordinates, and the system automatically performs all correction calculations. This is why we ask you to enter your birth location when generating a chart — it is not merely for record-keeping, but to ensure the accuracy of the hour determination.

子时（23:00-01:00）是十二时辰中唯一横跨两个日历日的时辰，这在八字命理中引发了一个持续了数百年的争议——“早晚子时”问题。 传统上存在两种观点： “早子时”派认为：23:00-00:00属于当天的子时（称为“晚子时”或“夜子时”），00:00-01:00属于第二天的子时（称为“早子时”）。也就是说，23:00一过，虽然日历还没翻页，但天干已经变为第二天的天干。这一派的理据是：子时是一天的开始，当子时到来时（23:00），新的一天在能量层面已经开始。 “不分早晚”派则认为：整个子时（23:00-01:00）统一归属第二天，日柱的天干地支在23:00就已经翻转为下一日的干支。 在当代命理实践中，大多数权威学者（包括Joey Yap）采用的是第一种方法的简化版：23:00-00:00出生的人，日柱推进一天（采用次日的日柱天干地支），时柱使用新的日干起算的子时。这确保了子时（23:00-01:00）作为一天的开始，其天干与次日的日干相匹配。 在我们的系统中，`normalizeDateTimeForBazi()`函数会自动处理这一规则：当出生时间在23:00至23:59之间时，系统会将日期推进一天，将小时设为0（即将“晚子时”视为次日子时的一部分），确保日柱和时柱的计算结果正确。 这个看似微小的规则差异可能对八字命盘产生重大影响——日柱的改变不仅影响日主本身（八字分析的核心），还会连带改变日支藏干、十神关系以及大运的排列。

The Zi hour (23:00-01:00) is the only traditional Chinese hour that spans across two calendar days, creating a centuries-old debate in Bazi destiny analysis known as the "Early and Late Zi Hour" problem. Traditionally, two viewpoints exist: The "Early/Late Zi" school holds that 23:00-00:00 belongs to the current day's Zi hour (called "Late Zi" or "Night Zi"), while 00:00-01:00 belongs to the following day's Zi hour (called "Early Zi"). In other words, once 23:00 arrives, although the calendar has not yet turned, the Heavenly Stem has already changed to the next day's stem. The rationale is that Zi hour marks the beginning of a new day, and when Zi hour arrives at 23:00, the new day has already begun on an energetic level. The "No Distinction" school holds that the entire Zi hour (23:00-01:00) uniformly belongs to the following day, with the Day Pillar's Heavenly Stem and Earthly Branch flipping to the next day's values at 23:00. In contemporary Bazi practice, most authoritative scholars (including Joey Yap) adopt a simplified version of the first method: for individuals born between 23:00-00:00, the Day Pillar advances by one day (using the next day's Day Pillar Stem and Branch), and the Hour Pillar uses the Zi hour calculated from the new Day Stem. This ensures that the Zi hour (23:00-01:00), as the beginning of a day, has its Heavenly Stem matching the following day's Day Stem. In our system, the `normalizeDateTimeForBazi()` function automatically handles this rule: when the birth time falls between 23:00 and 23:59, the system advances the date by one day and sets the hour to 0 (treating "Late Zi" as part of the next day's Zi hour), ensuring correct calculation of both the Day Pillar and Hour Pillar. This seemingly minor rule difference can have major implications for the Bazi chart — changing the Day Pillar affects not only the Day Master itself (the core of Bazi analysis) but also cascades into the Day Branch hidden stems, Ten God relationships, and the arrangement of Luck Pillars.

在八字命理中，四柱（年、月、日、时）各占命盘的四分之一权重，而时柱往往被视为最能反映个人内在性格和晚年运势的一柱。一个时辰的偏差不仅改变时柱的天干地支，还可能改变时柱与其他三柱之间的十神关系，进而影响对整个命盘的解读。 以十神（Ten Gods）为例：如果正确的时柱天干是庚金，对于日主甲木来说，庚金是七杀（Seven Killings），代表压力、竞争和激进的改变力量。但如果因为时间误差导致时柱天干变为辛金，则变成正官（Direct Officer），代表正当的权威、规则和自律——两者的性格解读截然不同。 时柱的准确性还直接影响以下方面： 藏干分析：时支的藏干（Hidden Stems）参与五行力量的计算。不同的时支含有不同的藏干组合，直接影响日主强弱的判定和用神（Yong Shen）的选取。 大运排列：大运的顺逆排列虽然由年干阴阳和性别决定，但大运的起算与月柱相关。如果时柱错误进而导致对命盘整体格局的误判，可能影响对大运走势的分析。 子女宫：时柱在传统命理中代表子女宫，关系到子女的缘分、数量和亲子关系。时柱的错误直接导致子女运势分析的偏差。 正因如此，真太阳时的修正不是可有可无的精细化操作，而是确保八字命盘准确性的基础性要求。《渊海子平》在论述时柱时就强调了时辰判定的重要性，认为差之毫厘，谬以千里。我们的系统内置了完整的真太阳时修正功能——只要您提供准确的出生时间和地点，系统就能为您计算出最精确的八字命盘。

In Bazi destiny analysis, the Four Pillars (Year, Month, Day, Hour) each account for one-quarter of the chart's weight, and the Hour Pillar is often regarded as the pillar that most directly reflects one's inner personality and fortune in later years. A one-hour discrepancy changes not only the Hour Pillar's Heavenly Stem and Earthly Branch but may also alter the Ten God relationships between the Hour Pillar and the other three pillars, consequently affecting the interpretation of the entire chart. Consider the Ten Gods as an example: if the correct Hour Pillar Heavenly Stem is Geng Metal, for a Jia Wood Day Master, Geng Metal is the Seven Killings, representing pressure, competition, and aggressive forces of change. However, if a time error causes the Hour Pillar Heavenly Stem to become Xin Metal instead, it becomes the Direct Officer, representing legitimate authority, rules, and self-discipline — the personality interpretations are entirely different. The accuracy of the Hour Pillar also directly impacts the following areas: Hidden Stem Analysis: The Hidden Stems within the Hour Branch participate in the calculation of Five Element strength. Different Hour Branches contain different Hidden Stem combinations, directly affecting the determination of Day Master strength and the selection of the Yong Shen (Useful God). Luck Pillar Arrangement: While the forward or reverse direction of Luck Pillars is determined by the Year Stem's yin-yang polarity and gender, the Luck Pillar calculation relates to the Month Pillar. If an incorrect Hour Pillar leads to a misjudgment of the chart's overall pattern, it may affect the analysis of Luck Pillar trends. Children's Palace: In traditional Bazi, the Hour Pillar represents the Children's Palace, relating to one's affinity with children, their number, and parent-child relationships. An error in the Hour Pillar directly causes deviation in children fortune analysis. For precisely these reasons, True Solar Time correction is not an optional refinement but a fundamental requirement for ensuring Bazi chart accuracy. The "Yuan Hai Zi Ping" (Sea of Jade Record), when discussing the Hour Pillar, emphasizes the importance of precise hour determination, cautioning that a tiny error at the start leads to an enormous deviation at the end. Our system includes a complete True Solar Time correction function — as long as you provide an accurate birth time and location, the system can calculate the most precise Bazi chart for you.