What does Sunrise & Sunset on Other Planets do?
Explore how long a day lasts on each planet — Mars days are 24h 37m; Venus has 117 Earth-day long days. Uses IAU rotation period data.
45°
Mars at 45°: about 12h 20m sunlight, 12h 20m night, 50.0% of one rotation.
Mars at 45°: about 12h 20m sunlight, 12h 20m night, 50.0% of one rotation.
Daylight summary
50.0%
- Axial tilt (reference)
- 25.19°
- Solar declination δ
- 0°
- Mean solar day (Earth time)
- 24h 40m
- Daylight (Earth hours)
- 12h 20m
- Night (Earth hours)
- 12h 20m
- Sunrise → solar noon
- 6h 10m
- Solar noon → sunset
- 6h 10m
Sky arc (schematic)
Orange = Sun above the geometric horizon along this ideal arc. Not a real camera view.
Day 50.0%
Night
“Earth hours” = how long sunlight lasts during one mean solar day on Mars. Dawn and dusk are symmetric around solar noon in this model.
How it works
- We use the standard spherical relation sin α = sin φ sin δ + cos φ cos δ cos H with Sun hour angle H. At geometric rise/set, α = 0 (equivalent to cos H = −tan φ tan δ away from singular poles).
- Optional Earth apparent mode sets α ≈ −0.83° for the Sun’s center—roughly refraction plus semidiameter. Other planets stay geometric for a single consistent story.
- Custom δ sweeps solar declination between ± each world’s listed obliquity—great for seeing how sensitive daylight is near solstice on Mars or Uranus.
- Mercury uses a mean solar day (~176 Earth days); Mars uses a sol (~24.6 Earth hours). Ice giants and Pluto use the same geometry with “surface” in scare quotes.
- Rotation without sunlight math: Planetary Day Converter. Orbital years: Orbital Year Converter.
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