Contrails? What?

Grafton's bedroom has a skylight, which provides a fairly wide view of the sky above and the street below our house...if you place your head right up to it.  Often, just before bedtime or right after being lifted out of the crib in the morning, I'll carry Grafton over to the skylight to "see what we can see" of the world outside.  (This used to be my secret technique for getting him to settle down when he refused to sleep.)

This morning we walked over to the skylight together in our pj's.  Dad saw some smoke emanating from the neighbor's chimney and pointed it out to Grafton, thinking he would find it interesting.  But he was too busy looking up at the sky. Uninterested in the chimney smoke, he pointed way up asked "What's that line?"  At first I didn't understand his question, but after he repeated himself, I realized he had spotted a contrail from an airplane that had flown overhead.  I explained to him all about airplane exhaust, atmospheric temperatures, and frozen vapor, and he listened intently.  I then noticed that Venus was bright and visible just below the contrail and told him about the planet that was up in the sky.  With our morning observations complete, we proceeded to get dressed and ready for the new day.

For me, the interesting thing was that I realized Grafton has started to ask the question "what is that?"  He had asked this "what" question a few times already in the previous few days, but it didn't register with me that it was a new form of inquisitiveness for him.  

I must also note that he hasn't asked the "why?" question much recently, but I have a feeling that one will start again soon.