Why are terrestrial planets denser than jovian planets?
A) Actually, the jovian planets are denser than the terrestrial planets.
B) Only dense materials could condense in the inner solar nebula.
C) Gravity compresses terrestrial planets to a higher degree, making them denser.
D) The Sun's gravity gathered dense materials into the inner solar system.
Question 2
Based on counting the number of galaxies in a small patch of the sky and multiplying by the number of such patches needed to cover the entire sky, the total number of galaxies in the observable universe is estimated to be approximately
A) 10 billion. B) 100 million. C) 100 billion. D) 1 trillion. E) 1 billion.