Click on the links in the calendar pane above to discover what might be seen on a particular night, to switch to a different month, or to call up the index of features.
The tour for any date relates to that night's viewing. So, for instance, clicking on the 12th of the month will show what can be observed on the evening of the 12th and/or the morning of the 13th.
In the nightly tours, many of the technical terms and all of the images are linked to extra notes which will appear in this pane, and clicking on the name of any physical feature will pull up a brief summary of its characteristics.
Because the moon's aspects and phases are irregular and uneven, and because you may be observing from anywhere in the world, it is impractical to produce a guide for exactly what you will see on a particular date. You may find that the visible features will be closer to those in the guide for the day before or the day after. Similarly, the same notes may occasionally appear on two consecutive days.
Although some of the features described are visible to the naked eye, most require a pair of binoculars (7 x 60 are ideal) and some really need a mounted telescope.
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
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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.