The Final Mercury Retrograde of 2021 and Its Defining Aspects

by Kaitlyn De Leonardis
final mercury retrograde 2022

Mercury is at it again! Yes, the “messenger” of our solar system is gearing up for its next retrograde. This is the final Mercury retrograde of 2021 and with Jupiter in Aquarius and Pluto in Capricorn involved, we’re in for another intense one. Mercury will be retrograde in Libra from September 26 to October 18. 

Why Are The Mercury Retrogrades of 2021 So Significant?

More often than not, the planet’s backward motion starts in one sign and ends in the neighboring one. This year is rare because the planet’s retrograde cycles are all happening in a single sign. In 2021, this transit occurs in all air signs​​Aquarius, Gemini and Libra. The element of air and the planet share some common themes like intelligence, judgment and communication. Thus, making these retrogrades extra mercurial and emphasizing the way we relate to one another. According to Astrology Zone, the next time Mercury retrogrades will occur in a single sign/element is in 2026, when they’ll happen solely in water signs.     

What Are The Major Themes of Mercury Retrograde in Libra?

With Mercury drifting backward through harmonious Libra, things could get rocky when it comes to close relationships (romance, business, friends or family). Libra is all about keeping the peace and attempts to avoid any form of conflict. But Libra is well acquainted with justice, and more often than not, some conflict is needed to achieve this. It’s important to remember that Mercury retrograde is all about reflection and review. Things from the past tend to make an appearance because they require some rehashing. At this time, you may find yourself circling back to a topic you thought had been tabled. 

Being that Libra is partnership-oriented, many people will be working through a compromise. Communication issues are synonymous with Mercury retrograde, so be sure to speak carefully and be patient if wires get crossed when dealing with others. This won’t be a one-and-done conversation. If you’re the type of person who holds their tongue for the sake of the status quo, you may find it impossible to do so any longer. Mercury in Libra searches for fairness and finding a balance between our own needs and our relationships is a major theme.    

Defining Aspects of Mercury’s Final Retrograde in 2021

Mercury is one of the fastest moving planets and the aspects it initiates with other celestial bodies are usually pretty quick, lasting for about a day. When Mercury is in retrograde, the alignments to these planets are drawn out. Due to its backward trek, the defining aspects of the retrograde will be hit a total of three times. Once during the pre-shadow, then during the retrograde itself and again in the post-shadow period. Taking a look at these angles and other planets involved can help us further understand what this retrograde is really about. 

The week before Mercury officially stations retrograde on September 26, it will form a helpful aspect to Jupiter and an indirectly helpful aspect to Pluto. The dates of this first set range from September 20 to September 25. Mercury trine Jupiter will call us to expand and grow, while Mercury square Pluto creates the need for a deep-rooted change. Trines create flow and ease between planets while squares create tension. Whether we willingly accept this change is another story. The Mercury-Pluto square will be the longest exact aspect of this transit. Pay attention (or think back) to what is transpiring between these dates. 

final mercury retrograde 2021

Mecury Retrograde Shadow Period l Photo by Carlos Vega 

September 26 – October 18

Retrograde Mercury swings back like a pendulum and hits these aspects to Jupiter and Pluto once more from September 29 to October 4. This time around Pluto goes first and we may be coming to terms with whatever transpired in the previous week or feel an inner push to initiate the change. Mercury retrograde is an optimal time to check in with our internal world, with the purpose of understanding what needs to be done in the outer realm. 

When Mercury connects with Jupiter for the second time on October 3, it may bring about an aha moment when pieces of the puzzle really come together. While some may chalk this up to coincidence, both Mercury and Jupiter will station direct on the same day, October 18. This is when solutions may be reached and we may finally be ready to open up to a blessing in our lives. Once everything is moving forward, Mercury activates the third round. It trines Jupiter on November 1 and squares Pluto on November 2. We’ll finally begin to realize how the final Mercury retrograde of 2021 worked in our favor. 

Mercury’s Cazimi 

During this retrograde, there’s another configuration to be aware of. It is a triple conjunction between Mars, the Sun, and Mercury on October 9. Mercury conjuncts the Sun during all its retrogrades. This is known as a cazimi and is typically the point where the retrograde (or issues that the transit brings up) reaches a peak. The previous Mercury retrograde in June of this year may have been significant for many because the cazimi happened during the solar eclipse in Gemini. 

With Mars involved this time around, passion and ambition will be at an all-time high. While we may want to forge ahead, be careful not to push too hard. At this time we’ll be a little more selfish, aggressive and combative. Tempers are likely to flare and lashing out could cause more drama than it’s worth.

Don’t fear the retrograde. What might feel like a major inconvenience is actually a minor one. It will lead to both crucial and significant developments.   

For more of how the final mercury retrograde of 2021 will affect your sign, check out your September 2021 Horoscope!   

Image by Astoko

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A writer and astrologer, sustained by iced coffee, sunsets and decorating her home. For more on her services and where her insights can be found, visit

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