Sources Eric Chaisson and Steve McMillan, Astronomy Today (Englewood Cliffs: Prentice-Hall, 1993), p. 550. Michael Zeilik, Conceptual Astronomy (New York: John Wiley & Sons, 1993), pp. 357–8.
Sources Eric Chaisson and Steve McMillan, Astronomy Today (Englewood Cliffs: Pren.tice-Hall, 1993), p. 55.0. Michael Zeilik, C:onceptu,al Astronomy (New Yo!rk: John Wiley & Sons, 1993), pp. 357–8.