Upon arriving at college and meeting your roommate, you sigh…

Upon arriving at college and meeting your roommate, you sigh mightily as you listen to his endless droning on about how wonderful his girlfriend back home is. “I miss her so much and can’t wait to see her during Thanksgiving break,” he comments. Knowing a bit about social psychology and the rules of interpersonal attraction, what are you most likely to think to yourself?

Spiral galaxies are classified in terms of increasing tightn…

Spiral galaxies are classified in terms of increasing tightness of their spiral arms as types Sa, Sb, and Sc. However, many spiral galaxies are aligned edge-on to Earth and their spiral arms cannot be seen. Which other parameter that is directly related to spiral-arm tightness can be easily seen edge-on and can therefore be used to provide this classification?