Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation is also known as the ocean's conveyor belt (which refers to deep ocean density driven ocean basin currents). These currents, called submarine rivers, flow under the surface of the ocean and are hidden from immediate detection.
The light-colored material is in areas of the Moon called the highlands, which represent the earliest crust on the Moon. Impact cratering shattered this crust and often deformed it, pushing some of it into mountain-high impact crater rims or ejecting it across the surface of the Moon.
In the photo on the right, we see a close-up view of a moderately large sunspot. The umbra is the darkest inner region, and the penumbra is the lighter, ray-like, uoter region of the sunspot. Sunspots can be small, 900 miles (about 1500 kilometers), or they can reach sizes up to 30,000 miles (about 50,000 kilometers).