Astronomical Time is a year-numbering system used by astronomers and scientists that includes a **year zero**, making it more mathematically consistent than the traditional Gregorian or Julian calendars.
# Overview In traditional calendars, there is **no year zero** — time jumps from 1 BCE directly to 1 CE. This makes historical calculations across the BCE/CE divide more error-prone. Astronomical time fixes this by including: - **Year 0** = 1 BCE - **Year -1** = 2 BCE - **Year -2** = 3 BCE - ... - **Year 1** = 1 CE - **Year 2** = 2 CE
This system is commonly used in **astronomy**, **chronological software**, and **scientific publications**, including the ISO 8601:2004 standard.
# Origin
Title: Astronomical Epoch BaseYear: 0 eventYear: 0
# Usage Astronomical time is ideal when performing date-based math that crosses the BCE/CE boundary. It is used internally in many scientific databases, astronomical simulations, and is supported by date libraries in programming languages such as Python and JavaScript.
# Example - Traditional 1 BCE = Astronomical year 0 - Traditional 500 BCE = Astronomical year -499 - Traditional 2525 CE = Astronomical year 2525
# Conversion Formula To convert from **Gregorian** to **Astronomical**: