You see two main-sequence stars with the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude, assuming there is no absorption of either star's light by interstellar gas or dust?
A) Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.
B) The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2.
C) Star 1 is 10 times more distant than Star 2.
D) Star 1 is 100 times more distant than Star 2.
E) Star 1 is 100 times nearer than Star 2.
Question 2
What is true of the Local Group?
A) It contains about 2500 galaxies.
B) The Andromeda galaxy is a satellite of the Milky Way.
C) The Andromeda galaxy (M31), and the Milky Way are the two largest galaxies.
D) The giant ellipticals are the largest members.
E) It consists of mostly spirals.
Apparent and True Orbits of Alpha Centauri.
The Pleiades, an open cluster of stars in the constellation of Taurus. These stars share a common mo
Dimmer Distant Supernova
Stars and constellations
Sequence of events from DNA to protein.
Comparison of A-type Climates