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AI Prompts for Mercury Retrograde Planning

Astrological calculation with LLM prompts for any AI platform for accurate Mercury Retrograde planning.

Three times a year, Mercury appears to move backward in the sky for about three weeks. Astrologers will warn you to expect communication misunderstandings, travel disruptions, and technology problems, but will also emphasize the retrograde period is well-suited for revisiting, revising, and reconnecting: the "re-" activities. AstroPrompt's Mercury Retro Planner shows a full year's schedule of Mercury retrogrades with exact station dates so you can plan around them. As with the Moon VOC Planner, this view has a practical appeal even among people who do not closely follow astrology. The view requires no personal birth data; Mercury retrograde applies to everyone.

The Mercury Retro Planner view uses the Astrolog calculation engine to compute Mercury's stations for the selected year, identifying the start, midpoint, and end of each retrograde period. The LLM receives the schedule and a forecast prompt that asks for the practical scheduling implications of each window.

Any current year's Mercury retrogrades are published at many websites so any LLM equipped with web search can get accurate Mercury retrograde schedules. The Mercury Retro Planner is in AstroPrompt as a convenience; you can also customize the prompt or add additional data so an LLM can give you more specific and personalized advice.

For an introduction to the process, see calculation-first AI astrology workflow.

Before you get started

Mercury Retro Planner is an option in the AstroPrompt navigation bar, and the fastest way to get a result is to use AstroPrompt. The tutorial below explains how to obtain the same result from any LLM yourself. To do it yourself you will need to install Astrolog, write the chart output to a file, and combine the Astrolog dataset with the prompts shown below. AstroPrompt makes the workflow easier: it runs Astrolog automatically, lets you pick from popular LLMs (such as OpenAI GPTs, Claude Opus, or Google Gemini), and streamlines the prompt assembly. For advanced users, AstroPrompt Pro lets you edit the prompts so you can customize tone, interpretation, or output structure. Try AstroPrompt now; it is FREE.

Mercury Retro Planner

The Mercury Retro Planner shows all Mercury retrograde periods for a selected year. Each period includes the start date (when Mercury stations retrograde), the end date (when Mercury stations direct), the signs Mercury moves through during the retrograde, and the exact station times.

No birth data is required. Mercury retrogrades are a sky event applicable to everyone (a "mundane" event). The prompt asks "What does Mercury retrograde mean?" and the full report offers to generate an ICS file with each retrograde day as a calendar event.

How to get an accurate LLM response

AI can't calculate planetary positions accurately or read an ephemeris reliably. To get an accurate and reliable interpretation, you must provide this astrological data:

  • The complete list of Mercury retrograde periods for the year, typically three.
  • Start and end dates for each period (the station retrograde and station direct dates).
  • The signs Mercury occupies at each station and any sign changes mid-retrograde.

Astrolog commands

The Mercury Retrograde calculator runs a single yearly ephemeris command and parses the retrograde flag:

astrolog -qy {year} -dy -R0 3 -z 0
  • `-qy {year}` runs Astrolog for the entire year, year-quick mode.
  • `-dy` outputs the daily ephemeris table for the year, with one line per day.
  • `-R0 3` restricts the output to planet 3 (Mercury). Astrolog numbers the planets internally, and 3 is Mercury.
  • `-z 0` forces UTC output so retrograde station dates and times are stored consistently across user timezones.

AstroPrompt runs additional processing on the Astrolog output, parsing the output to find the start of retrogrades and the stations direct and performing some caching for computation efficiency.

Prompts

Astrological data is combined with a user's prompt to create the context for a question that begins an AI chat. The LLM receives everything (including its responses to previous questions) as a single context block, but it is easier for us if we assemble the context from three specific prompts: a system prompt, a data description prompt, and a user prompt that asks for a report. In AstroPrompt Pro, you can edit and save each of these prompts to customize tone, interpretation, or output structure. For this tutorial, combine each of these prompts with the astrological data and then paste the entire block into the AI chat.

System Prompt

The foundational instruction that sets the AI's overall tone, style, and approach, which applies to every message in the conversation. The default produces balanced, measured analysis. You can change it to anything: terse bullet-point summaries, a specific cultural or traditional framework, a particular language, or even a lengthy style guide that reproduces your own voice for client-facing work. This is the most powerful lever for fundamentally changing the character of the AI's responses.

The system prompt is shared across every AstroPrompt view:

When generating astrological forecasts, do not use rhetorical or
        persuasive devices typical of popular horoscope writing. Avoid inserting
        emotional appeals or literary devices. Avoid the following:

        • Imperatives and exhortative tone (e.g., "Embrace change," "Let go of
          the past," "Surround yourself with warmth")
        • Evocative metaphors and symbolic language (e.g., "personal
          renaissance," "magnetic energy," "mirror of the soul")
        • Overly enthusiastic, poetic, or cute phrasing
        • Vague affirmations or inspirational advice not grounded in planetary
          positions

        Instead, use a neutral, informative tone. Focus on:

        • Relevant planetary influences and their timing
        • Which life areas are affected and how
        • Expected themes based on astrological interpretation
        • Possibility framing using modal verbs (e.g., may, might, could)
          without interpretive flourish
        • Objective language suitable for readers seeking analysis rather than
          affirmation

        Structure any planner forecast by timeline or topic (e.g., career,
        relationships, health).

AstroPrompt adds a terminology directive (advanced or beginner) based on its settings.

Data Description

This prompt tells the AI what the raw astrological data actually represents. This is how the AI understands the underlying dataset. Advanced users can use this to direct the AI's attention toward specific technical elements they care about most.

After the parsed retrograde schedule, AstroPrompt appends a one-sentence description:

This data contains Mercury Retrograde periods for the selected year,
        including the start and end dates for each retrograde period, the signs
        involved, and the station dates (when Mercury stations retrograde and
        stations direct).

The "stations retrograde" and "stations direct" wording matters because the model needs to know that station dates are different from period boundaries.

Full Report Prompt

AstroPrompt provides detailed instructions when a user wants a full report. This is typically the longest prompt and has the greatest single impact on report quality and structure. The default walks the AI through a specific analytical sequence. You can replace this entirely as you wish, for example, to focus the report on career and finance, restructure it around specific techniques, or direct the LLM to use the point of view of a favored lineage or tradition.

The full report is a calendar-export prompt:

Given this dataset of Mercury Retrograde periods for the year, ask me if
        I want the following: A downloadable ICS calendar file adding a Mercury
        Retrograde full-day event to each day during the Mercury Retrograde
        periods. The file should be properly formatted for import into Google
        Calendar, Apple Calendar, and Outlook.

The prompt is short because the deliverable is constrained. The model is expected to ask for confirmation, then produce a single ICS file with one full-day event per day in each retrograde window.

Unique features of the Mercury Retro Planner prompt

  • The whole year is computed in one Astrolog call (-qy -dy) rather than a per-day query, which is dramatically faster.
  • Mercury is selected by Astrolog's internal planet number 3 via -R0 3, restricting the daily ephemeris to a single body.
  • All station dates and times are stored in UTC and translated to the user's display timezone at render time.
  • Year-level results are cached so navigating between years is instant after the first lookup.
  • The full report prompt is a single deliverable (ICS) rather than an interpretation, matching how users actually want this data.
  • The same calculation feeds the Daily Planner alerts pass, so retrograde status appears consistently across views.

What's Next

This was written in May 2026, describing the data and prompts used in AstroPrompt version 1.0. Astrologers are just beginning to explore the capabilities of AI as a tool for astrological insight. If you've got suggestions for a better dataset or improved prompts, I'd love to hear from you. Email me at hello@timecasters.com.