Clicking "Navigate" or "Gazetteer" beneath the title in the top-right pane allows you to choose how to jump between the high-resolution charts: by chart area or by feature name.

In "Navigate", click on the main grid and the corresponding chart will be shown on the left. You can also toggle map overlays and switch the chart orientation. Occasionally it can be difficult to read labels against a particular landscape, in which case use the "blank" option. A selection of lunar maps and articles is also available from here.

The "Gazetteer" consists of a list of named features and the charts they appear on. Clicking on any of these will call up that chart. Because the list is quite long, the alphabetical index above it allows you to scroll instantly to the required part of the list.

The margin of each chart shows areas covered by adjacent charts. Click on an arrow in this margin to pan to the next chart.


In order to produce consistently sized and scaled charts, the images are composites of photographs taken at different times, months or even years apart. Libration (the pitching movement of the Moon) and parallax effects mean the Moon can be rotated by up to 18° between different photographs, and the direction of the Sun may vary by nearly 180°. Whilst a great deal of care has been taken to select compatible images and to manipulate them to cancel out the effects of rotation, it is impractical to achieve perfect realism. You may still find subtle distortions of topography and impossible combinations of illumination!


Inconstant Moon is divided into three main sections: Lunar Tours - a nightly illustrated guide to what is visible on the Moon, Cyclopedia Selenica - our reference library with articles, bookstore, webguide and interactivities, and Selenographia - a zooming, panning, cross-referenced atlas of the Moon.

Move between the sections by clicking the links in the top-right pane.

If you are looking for something specific, try the site search


To work properly, Inconstant Moon needs a frames-capable browser such as Netscape Navigator or Microsoft Internet Explorer with JavaScript enabled. Ideally you will be viewing on an 800 by 600 pixel screen (or larger) with 256 colours (preferably more) and MIDI sound enabled.

Cookies may be used to store your preferences (music or silence, images north-up or south-up, etc.) They are not used for any other purpose, and accepting them should enhance your enjoyment of the site on future visits.

For the benefit of anyone of a nervous disposition, we’ve rated straight zeroes with RSACi.

If you have technical difficulties, check out the Frequently Asked Questions.

Inconstant Moon