How to observe Sinus Iridum
Watch the mountain arc close to lunar sunrise: its illuminated rim can stand out while nearby ground is still in shadow.
Finding the region
Look at 45.01° N, 31.67° W on the lunar disc. The chart marker identifies the catalogue centre. Start with a wide field and use the nearby formations below as landmarks.
Equipment & conditions
These dark plains are a good starting point with binoculars. Trace their shapes at low power, then examine the boundary with the brighter highlands. Higher sunlight helps reveal brightness differences; low sunlight brings out ridges.
Lighting
For surface relief, try a time when the Sun is low over this region. To compare surface brightness and any bright rays, return under higher illumination. The atlas calculates the solar elevation at the formation’s centre for any selected date.
View Sinus Iridum in the atlas →
