Although I was thrilled, as usual, to hear of yet another discovery that might lead us to our brethren in the universe, I was dismayed to learn that our scientists have been in such disagreement about the requirements for planetary existence. It made me worry about how many other “requirements” they may have all wrong.

Joyce Stillman
Odessa, N.Y.

The article describes the oldest planet known in the universe, about 12.5 billion years old, to be 7,200 light-years from Earth. Doesn’t that contradict Hubble’s law, which states that distance is correlated with age?

Jeffrey Freed
Tacoma, Wash.

No, old objects can be nearby or far away. The object is seen as it was 7,200 years ago, but at that time, the star and the globular cluster that it’s in were already quite ancient .–R. Cowen