🔭 日期转儒略日Convert Date to Julian Day

使用说明与常见问题How-to & FAQ

「日期转儒略日」是什么？What is the Convert Date to Julian Day tool?

把公历日期转换成儒略日编号 JDN。本地处理。可设置「输出」。Convert a Gregorian date to Julian Day Number (JDN). Processed locally. Settings: Output.

如何使用「日期转儒略日」？How do I use the Convert Date to Julian Day tool?

输入一个 YYYY-MM-DD 日期，在“输出”里选择儒略日数 JDN 或当天 00:00 UT 的儒略日 JD，结果显示在下方。Enter a date as YYYY-MM-DD and choose under "Output" whether you want the Julian Day Number or the Julian date at 00:00 UT; the result appears below.

JDN 和 JD 有什么区别？What is the difference between JDN and JD?

儒略日数 JDN 是天文用的连续整数日编号，每个儒略日从世界时（UT）正午 12:00 开始，所以 JDN 对应这一天的正午，例如 2000-01-01 的 JDN 是 2451545。儒略日 JD 是带小数的连续时间：当天 00:00 UT 的 JD = JDN − 0.5（2026-10-20 → 2461333.5）。用“输出”选择要哪一个，另一个显示在结果下方。The Julian Day Number (JDN) is the continuous integer day count used in astronomy. Each Julian day starts at noon (12:00 UT), so the JDN refers to the noon of the date — 2000-01-01 is 2451545. The Julian date (JD) is a continuous fractional count, and at 00:00 UT on the date JD = JDN − 0.5 (2026-10-20 gives 2461333.5). Choose which one you want under Output; the other is shown below the result.

用的是哪种历法？和时区有关吗？Which calendar is used, and do time zones matter?

所有日期都按外推格里高利历（proleptic Gregorian，即把现行公历规则向前一直沿用）计算，年份 0000–9999，0000 年即公元前 1 年。1582 年 10 月 5 日到 14 日在历史上采用格里高利历时被跳过，从未实际存在；页面仍按外推公历计算这些日期，并在结果下方给出提示。计算只用你输入的日期，不读取设备时钟，所以时区和夏令时不影响结果。输出的年份总是 4 位（如 0005-06-07）。All dates are proleptic Gregorian: today's calendar rules applied backwards without a break, for years 0000–9999 (year 0000 is 1 BC). The days 1582-10-05 to 1582-10-14 never existed in the Gregorian calendar as historically adopted — they were skipped — so the page still computes them as proleptic dates but shows a note below the result. Only the dates you type are used and the device clock is never read, so time zones and daylight saving time do not affect the result. Years are always printed with 4 digits, e.g. 0005-06-07.

输入和输出是什么样的？What does the input and output look like?

例如在「日期转儒略日」中输入 2000-01-01，输出为：2451545。For example, the Convert Date to Julian Day tool turns the input 2000-01-01 into: 2451545.

有哪些选项可以调整？What options can I adjust?

「日期转儒略日」的设置：「输出」可选 儒略日数 JDN（整数）、儒略日 JD（当日 00:00 UT）（默认 儒略日数 JDN（整数））。每次生成结果都按当前设置处理。Settings in the Convert Date to Julian Day tool — "Output": Julian Day Number (integer), Julian date at 00:00 UT (default Julian Day Number (integer)). The result always uses the current settings.

「日期转儒略日」免费吗？需要注册吗？Is the Convert Date to Julian Day tool free? Do I need an account?

「日期转儒略日」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Convert Date to Julian Day tool is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.