1. Ursa Major is best known as the home of the Big Dipper. Out of all the constellations, the Big Dipper is the most recognized. It's always above the horizon in the northern latitudes. The best time to see it is in the spring when its high above the northeastern horizon.
2. A group of stars that make an imaginary shape in the sky is called a constellation. They are usually available to see with you bare eye, but if the sky is cloudy then no. Some examples of constellations are the Ursa Major-The Great Bear, Orion-The Hunter, Gemini-The Twins, and Taurus-The Bull.