"astrological sign" is not accurate/apt enough[change source]
The text "A person's astrological sign is based on his birthday" requires some clarification for 'political correctness'. Please consider allowing my edit of "astrological Sun sign" instead (not to mention, it may be better for Wikipedia entries to be more gender sensitive).
If you don't understand why it's important to make this distinction, I invite to you thoroughly peruse the two newer links (as listed in the Other Websites section in the entry page of Astrology, for a start :).
This refusal would only encourage a misconception of what an "astrological sign" is.