Interactive Tools

Space calculators

Interactive tools for exploring space and astronomy. More calculators are on the way.

Weight on Other Planets

See what you'd weigh on Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune.

Real light-travel time between planets and stars, plus a custom km/AU/light-year/parsec converter.

Real synodic lunar phase for any date, with astrophotography advice and upcoming phase-change projections.

Estimate a coronal mass ejection's transit time from the Sun to Earth based on its launch speed.

How long would a radio message take to reach Mars, Jupiter, or Proxima Centauri?

If you drove there non-stop, how long would it take to reach the Moon or Pluto?

What can you actually expect to see at your sky's Bortle darkness class?

Calculate your telescope's true magnification from focal length and eyepiece size.

Find your telescope's real useful magnification ceiling before the image blurs.

Find the peak dark, twilight-free window between sunset and sunrise.

Adjust a shower's published rate for real-world cloud cover and moonlight.

A starting point for astrophotography sub-exposure length based on your Bortle class.

Real surface gravity ratios and orbital periods for Mars, Jupiter, and the Moon.

Real synodic moon phase math — days until the next New, Quarter, or Full Moon.

How far north do you need to drive from your city to reach the current aurora boundary?