Single source of truth for Mercury Retrograde dates

[Charles]

I’m trying to find out if there is a single source of truth/dates for when Mercury Retrograde occurs. For example, how does everyone agree that it occurs during a specific time, e.g. January 30 – February 21.

Discussion

[StellaGraphia]

It’s called an ephemeris. It’s what any astro site, or astrologer, uses to determine positions. And every astrologer has one, whether the print book or digital. [Astro.com](https://Astro.com) provides pdfs of many centuries of them for free. Under the “All About Astrology” tab at top of page, find the “Ephemeris” heading. Under that you will see links for this year, etc. but to access all of them, to peruse what you want, click on the [9000 Years Ephemeris](https://www.astro.com/swisseph/swepha_e.htm) link. You can download just a one-year pdf (any year you want) or do a pdf that includes 50 years, etc. Here’s the one for 2021:

[2021 Ephemeris](https://www.astro.com/swisseph/ae/2000/ae_2021.pdf)

In the ephemeris, in the columns of the planets that do have retrograde cycles, **you will find an “R” beside the planetary position on the day it goes retrograde**. (Positions are stated for midnight on that date, so it won’t give an exact time – use the chart making function on [astro.com](https://astro.com) or [astro-seek.com](https://astro-seek.com) to discover the exact minute). Then, **when it goes direct, there will be a “D” beside the planet’s position numbers.**

To understand more about an ephemeris, and to understand how it is created, [then read this.](https://www.astro.com/swisseph/swephinfo_e.htm)

You can also make use of sites that have calculated the year’s retrogrades for you, such as at Astro-Seek. [Here are 2021’s.](https://horoscopes.astro-seek.com/retrograde-planets-astrology-calendar-2021)

The ephemeris also comes in book form, available on Amazon. “The American Ephemeris” by Michelsen. It’s not just for America, it’s global. It’s just the name of it.

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