Example Data Table
These examples use the default custom scale and lunar reference.
| Example Date |
Stardate |
Moon Phase |
Moon Age |
Illumination |
| 2026-01-01 00:00 UTC |
109,497.00 |
🌔 Waxing Gibbous |
12.08 days |
92.06% |
| 2026-03-20 12:00 UTC |
109,575.50 |
🌒 Waxing Crescent |
1.99 days |
4.41% |
| 2026-06-21 18:00 UTC |
109,668.75 |
🌓 First Quarter |
6.65 days |
42.21% |
| 2026-09-23 06:00 UTC |
109,762.25 |
🌔 Waxing Gibbous |
11.56 days |
88.79% |
Julian Day: JD = Unix seconds / 86400 + 2440587.5
Custom stardate: Stardate = Base + Days from epoch × Units per day
TNG-style stardate: Stardate = 1000 × (Year - 2323 + Fraction of year)
Moon age: Moon age = (JD - Reference new moon JD) mod Synodic month
Illumination: Illumination = (1 - cos(2π × Moon age / Synodic month)) / 2 × 100
The lunar zodiac value is approximate. It estimates Sun longitude first. Then it adds the lunar phase angle.
How to Use This Calculator
Choose a date and time first. Select the matching time zone offset. Pick a stardate model. Use the custom model when you want a modern online scale. Use the TNG-style model for fictional era comparison. Use the Modified Julian date option for astronomy-style numbering.
Keep the default lunar settings for normal use. Change the synodic month or reference new moon only when you need custom research settings. Add an observer note if you want it included in downloads. Press calculate. The result will appear above the form. Use CSV for spreadsheet work. Use PDF for a printable report.
Stardate and Moon Phase Guide
A Practical Space Time Tool
A stardate gives a date a space themed number. It is useful for logs, games, fiction, lessons, and themed reports. There is no single universal stardate rule. Different stories and fan systems use different scales. This calculator solves that problem by offering three models. The custom model is simple. It starts from an epoch. It then adds chosen units per day. The TNG-style model follows a common fictional approximation. The Modified Julian option gives a real astronomy based number.
Moon Phase Meaning
The Moon changes appearance because sunlight reaches it from changing angles. A new moon is near the Sun in the sky. A full moon is opposite the Sun. Crescent phases are thin. Gibbous phases are mostly bright. The calculator estimates the lunar age in days. It then converts that age into phase name, phase angle, and illumination.
Planning Observations
Moon phase matters for sky watching. A full moon is bright. It can hide faint stars and galaxies. A crescent moon gives darker skies. First quarter is great for crater shadows. Last quarter works well before sunrise. The next key phase helps you plan ahead. It shows when the next quarter, full moon, or new moon occurs.
Advanced Options
The reference new moon sets the start of the lunar cycle. The synodic month controls cycle length. The default value is suitable for general estimates. Exact lunar motion is more complex. The Moon moves in an elliptical orbit. Its speed changes. Professional ephemeris software handles those effects. This page is best for educational use, quick planning, and themed stardate reports.
1. What is a stardate?
A stardate is an alternate date numbering system. It is often used in science fiction, logs, games, and themed calculators.
2. Is there one official stardate formula?
No. Many fictional series and fan tools use different rules. This calculator includes custom, TNG-style, and Modified Julian models.
3. How accurate is the moon phase result?
It is a strong general estimate based on a synodic month cycle. It is not a full professional ephemeris calculation.
4. What is moon age?
Moon age is the number of days since the last new moon. It usually ranges from zero to about 29.53 days.
5. What does illumination mean?
Illumination is the estimated percent of the Moon disk lit by the Sun from Earth view.
6. Why does time zone matter?
The Moon phase changes with time. The time zone helps convert your selected local date into the correct UTC moment.
7. Can I export the result?
Yes. Use the CSV button for spreadsheets. Use the PDF button for a simple printable report.
8. Can I change the lunar reference?
Yes. Advanced users can edit the reference new moon JD and synodic month length for custom cycle studies.