The astronomers then conducted an analysis called a Bouger correction in order to subtract the gravitational effect of topological features, such as valleys and mountains, from the total gravity field. What is then left is the gravity field hidden beneath the lunar surface, existing within its crust. The moon, for the most part, influences our emotions. In certain phases of the moon, the predictions made through the study of astrological phenomena that would otherwise occur fail to happen, because our emotions do not produce the reactions to the astrological phenomena that would normally be expected. In other phases of the moon, astrological phenomena of planetary alignments and their effect on the Zodiac sun signs are not altered from their original reading. Vast regions of dark dunes also extend across Titan's exotic landscape, especially around its equatorial regions. Unlike Earth's sand, the "sand" that creates Titan's dunes is composed of dark grains of hydrocarbon that resemble coffee grounds. The tall linear dunes of this misty moisty moon-world appear to be quite similar to those seen in the desert of Namibia in Africa. Because Titan's surface is pockmarked by relatively few impact craters, its surface is considered to be quite young. Older surfaces display heavier cratering than more youthful surfaces, whose craters have been "erased" by resurfacing. This resurfacing is caused by processes that cover the scars left by old impacts as time goes by. Our own planet is similar to Titan in this respect. The craters of Earth are erased by the ongoing processes of flowing liquid (water on Earth), powerful winds, and the recycling of Earth's crust as a result of plate-tectonics. These processes also occur on Titan, but in modified forms. In particular, the shifting of the ground resulting from pressures coming from beneath (plate tectonics), also appear to be at work on this veiled moon-world. However, planetary scientists have not seen signs of plates on Titan that are analogous to those of our own planet.