108 m/s) c2 kg S2 A) 300 million km B) 3 million km C) 30 km D) 3 km E) 3,000 km 29) What is a pulsar? A) A white dwarf in a binary system that is accreting matter from its companion star, emitting pulses just before exploding as a supernova B) An Earth-based lighthouse that sends signals into space to search for extra-terrestrial life. C) A star that is burning hydrogen in phases, each phase corresponding to a pulse of radiation from the star D) A black hole E) A magnetized neutron star that is rotating rapidly and emitting a beam of radio emission, which is observed as pulses when the beam sweeps the earth 30) Suppose two lines appear to be parallel but eventually meet. What type of geometry are you dealing with? A) saddle-shaped geometry B) spherical geometry C) at geometry D) Euclidean geometry E) This situation can never occur. 31) What is the ultimate fate of an isolated white dwarf? A) As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova.