What it is

Confused about the current moon phase? Want to know how the moon would look like, now at noon? Moonlight to the rescue for the amateur werewolf, the interested hobby astronomer or, really, everybody!

Moonlight features a photorealistic display using OpenGL rendering technique that paints the moon's current appearance including all variations in distance, equatorial ecliptic angle and moon libration.

The application uses an accurate astronomical model of the solar system using the JPL (NASA's Jet Propulsion Laboratories) ephemeris data for dates between the years 2000 and 2020.

The program takes the observer's (that is you) current position and time into account for exact rendering of images. Alternatively, you can enter your own coordinates and view the moon from anywhere in the world.

Go into time warp mode and accelerate time: Fast forward or rewind to see how the moon changes over time.

Moonlight not only displays a pretty 3D image but also shows various essential data points: moon phase, distance between earth and moon julian date or local sideral time.

Dual moons

But how precise is the calculation? Here on the left is a photograph of the moon on October 17th alongside a screen shot on the right from the application at about the same time. Judge for yourself how near the reality the simulation is.

Waxing moons

Moving through time is just a button press away. Accelerate time and watch the moon change shape. See this Animation how it wanes and waxes!

Frequently asked moons

Q: In time warp mode, the moon seems to get larger and smaller, that surely isn't right?

A: Yes it is. The moon travels on an ellipsoidal trajectory around earth and thus its distance varies between 364.000 and 406.000 km. This change in distance is what you see as getting larger and smaller.

Q: Do I need to connect to your server for astronomical data?

A: No. No internet connection is required. All astronomical data is contained within the application.

Q: I see the moon wobble around, doesn't it show always the same side to earth?

A: Yes it does, but it also wobbles. This is called "libration" in astronomical terms.

Q: How do you calculate all that stuff?

A: We're using the JPL ephemeris library (http://www.ephemeris.com/software.html) to get exact space coordinates for earth, moon and sun and continue from there. Thanks to Dr. E. Myles Standish of NASA's Jet Propulsion Laboratory for the JPL ephemeris files DE405.

Q: I found a bug! I have an idea for a feature!

A: Then by all means get in touch! Email us at feedback-moon@darkgiraffe.com.