I received some questions from a former student:

So I’m taking an astronomy class this semester, and just learned about perihelions and aphelions in ellipses. I’m thinking it has a Greek (ancient Greek) tie in, since Helios was the old sun god in Greek mythology. But I have no idea what “peri” or “ap” mean in ancient Greek, so I thought I should ask you. :p

Also, I saw on your tip of the day email that you’re planning on taking people to Italy next year. Are you finally taking students? I know you were talking about that at one point, and wondered if these mysterious “people” might be that. 🙂


Here is my reply:

Good to hear from you!  I hope college is going well!

You are correct.  These are “Greek” words.  Aphelion comes from απο (from, far from) and ηλιος (sun).  As you know, this is when the earth is farthest from the sun.  περι (near) and ηλιος (sun) team up to form perihelion, the point when the earth is near the sun.

Yep.  I am finally going to do it.  I am teaming up with my good friend David Durham to take trips to Italy. The first one will happen (if all goes well) in the summer of 2017.  Wanna come?  🙂

Have a happy Monday!

Dwane Thomas