How to sort date ranges in Python3 without using the year?

Hey there, I’m fairly new to coding and am currently learning Python3. I am working on an independent project to test out what I’m learning, and one of the functions I’d like to implement is to tell the user their zodiac sign based on their inputs of birth day, month, and year.

Where I’m stuck is figuring out how to create returns for certain ranges of dates (ex. 4/20 through 5/20 equals Taurus, 9/23 through 10/22 equals Libra, etc) without having to factor in a birth year. I’ve imported the datetime module and am working with that. Should I not use datetime at all?

Any comments or assistance or feedback would be greatly appreciated. Here’s a link to my project so you can see the code I’ve written so far: