Planet name

[adastra]

Why most extrasolar planet names start with the letters HD

[LowlyPion]

I believe they are named for the stars that they orbit. HD is a common star name because it appears listed in the Henry Draper star catalog. Hence you see names like HD ####### followed by lowercase letter designating which planet out with "a" being the closest in planet.

This is my understanding anyway.

[adastra]

thank you