Radau Crater is an impact crater in the Oxia Palus quadrangle of Mars, located 17.1° N and 4.8° W. It is 114.5 km in diameter and was named for Rodolphe Radau, a French astronomer (1835–1911). Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10 km in diameter) they usually have a central peak. The peak is caused by a rebound of the crater floor following the impact.
Image:Wikiradau.jpg|Radau Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter). Image:Wikiradaudunes.jpg|Dunes in Radau Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter). Note: this is an enlargement of a previous image
The Radau is a river in the German state of Lower Saxony and is a right tributary of the Oker.
It rises at around in the Harz mountain range, in a bog known as the Torfhaus Moor (also Radauborn Moor) east of the Torfhaus village in the municipality of Altenau. The river flows northwards through the Radau valley that it has carved out and feeds the 23 m high Radau Waterfall south of Bad Harzburg immediately next to the B 4 federal road. The artificial waterfall was constructed as a tourist attraction in 1859 on behalf of the Duchy of Brunswick State Railway, which had operated the Brunswick–Bad Harzburg railway line since 1841. After passing through Vienenburg, the Radau discharges into the Oker river northeast of the town.
In the Middle Ages the Radau was used for the rafting of logs and wooden palettes stacked with peat. To that end the river was dammed by 6 raft locks. The goods to be rafted, that had previously been dropped in the river, were transported downstream with the additional weight of water.
At the Radau Waterfall is a restaurant and a children's railway integrated into the landscape.