Our birthdays are the day we're born, but our astrological birthday is when the transit (moving) Sun returns to the exact same position it was at when we were born, and happens the day before, day of, or day after our birth date. It's called a Solar Return.
In astrology, it's believed that your solar return and what happens to you for 24 hours afterwards can show what will happen to you over the next year of your life. Every two hours is equal to one month of your life, and it can be interesting to see how what happens in the 24 hours links to the next 12 months. The hours you're sleeping usually show the months that are the calmest or most uneventful, and the hours you're awake show the months when things will be happening.
I've noticed that if I ever sneeze or cough or hit my arm or something like that, the days associated with that time are days I'll be sick. The time when I'm exercising shows the period of the year I'll be most focused on my health. Keep track of what's happening for 24 hours starting at the time of your Solar Return (you can generate a Solar Return chart for free on astro.com). See how it manifests for you!
Mercury Retrograde in Sagittarius: December 2017
January 2018 New & Full Moons
December 2017 New & Full Moons
Jupiter in Scorpio: October 2017 - November 2018
Saturn in Capricorn: December 2017 - March 2020, July - December 2020
Saturn in Sagittarius: December 2014 - June 2015, September 2015 - December 2017
Saturn in Sagittarius for Each Sign