- Rubidium (Wikipedia)
Rubidium is a chemical element; it has symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes: 72% is a stable isotope 85Rb, and 28% is slightly radioactive 87Rb, with a half-life of 48.8 billion years – more than three times as long as the estimated age of the universe.
- Sea of Azov (Wikipedia)
The Sea of Azov (Crimean Tatar: Azaq deñizi; Russian: Азовское море, romanized: Azovskoye more; Ukrainian: Азовське море, romanized: Azovs’ke more; Adyghe: Хы мыутӏэ, romanized: Xı mıut’ə) is an inland shelf sea in Eastern Europe connected to the Black Sea by the narrow (about 4 km (2.5 mi)) Strait of Kerch, and is sometimes regarded as a northern extension of the Black Sea. The sea is bounded by Russia on the east, and by Ukraine on the northwest and southwest, currently under Russian occupation. It is an important access route for Central Asia, from the Caspian Sea via the Volga–Don Canal.