Some constellations such as Ursa Minor, are visible in the sky year round other constellations appear for only part of the year.Explain why this happens.

Answer 1

http://curious.astro.cornell.edu/question.php?number=300

Note that if you are in the Northern hemisphere You can see stars that are high in the northern sky all year. It is the ones close to the plane of the earth's orbit that you can only see when you are facing them at night.