(a) This section applies only to real estate subdivisions subject to the plat approval authority of the commissioners court of a county.
(b) The commissioners court of a county, any part of which is located within 57 miles of a major astronomical observatory at the McDonald Observatory, shall adopt orders establishing standards relating to proposed subdivisions to minimize the interference with observatory activities caused by outdoor lighting.

(c) The commissioners court of a county, any part of which is located within five miles of a major astronomical observatory at the George Observatory or the Stephen F. Austin State University Observatory, may adopt orders establishing standards relating to proposed subdivisions to minimize the interference with observatory activities caused by outdoor lighting.
(d) A commissioners court that adopts orders under this section may not approve a plat of a proposed subdivision that does not meet the standards established in the orders.