Why did you and your best friend's menstrual cycle sync?
Your menstrual cycles synced because of coincidence - the idea that womens cycles sync up due to some mystic feature of womens bodies is nonsense. It's inevitable that at some points two women's cycles are going to overlap at some points, it's basic mathematics that's all.
If you have a normal average menstrual cycle of say 28 days then you ovulate around the middle of the menstrual cycle which wil be 14 days after the first day of your menstrual bleeding. keeping in mind that sperm can live for 4 days inside the woman's reproductive organs you will have to allow at least 4 days before the 14th day. in other words if you dont want to get pregnant definitely dont…
If you do you could get pregnant. This is not a good idea if you don't want to be. Keep taking them. What pill are you on?????? Generally speaking, you can stop at any time but you will suffer cycle irregularities. You may not get your period for a few months or you may bleed excessively. When you take "the pill", the hormones in it trick your body into thinking it is pregnant, so if…
Your periods aren't determined by the dates on the calendar, they are determined by your menstrual cycles and your cycles will never perfectly sync up with the calendar months. The average menstrual cycle is 28 days which is shorter than a month, cycles can change, and months aren't all the same lengths - there's no reason at all to think your period would always occur on the same day every month.
"Active Sync" is basicly the same thing as "Sync" or "Syncing". It means "downloading" in another word. What it means is, anything that you have downloaded for your ipod/iphone or phones etc, you have to sync it able to have it on your device. If you dont sync, it will not be on your device automatically but will be saved on your computer, so you can sync anytime when your ready.
Its not so much to do with an astronomical cycle, though the 365 days for the earth to rotate the sun does come into it. The tzolk'in calendar has 20 day names which then cycle 13 times to make 260 unique days. A normal year has 365 days, so to the two calenders are out of sync. It takes 52 years for the days to match up again, for the cycle to restart.