Robert is looking at four galaxies: an irregular galaxy the he calls “Calliope”; a spiral galaxy that he calls “Medea”; an elliptical galaxy that he calls “Minerva”; and a lenticular galaxy that he calls “Ariadne”;

Question

Which of these four is the youngest?

A. Medea
B. Ariadne
C. Minerva
D. Calliope

Answer 1

Irregular galaxies, like the one Robert calls "Calliope," are generally considered to be the youngest type of galaxy. They often contain a lot of gas and dust, which allows for ongoing star formation. In contrast, elliptical galaxies (Minerva) are typically older, with less active star formation as they have used up much of their gas and dust.

Therefore, the youngest galaxy among the options listed is:

D. Calliope