Small pieces of ice, rock burning up in Earth's atmosphere. E.g. Pleiades, Hyades, M13. Key to interpretation of stellar evolution. E.g. Great Nebula in Orion. Mark birthplace of young stars.
Brighter objects have smaller values.
There are only 11 stars brighter than magnitude 1 visible from Charlottesville but 1630 stars brighter than magnitude 5. Time Tracking changes in sky with time, e.g. sky motions, with time of day, month, year shows regularities or time cycles. What you can see in the sky is determined by the Earth's orientation and motion. The horizon plane is different at each location on Earth. The CS is an imaginary hollow sphere centered on Earth.