Astrology Quick Facts:


Ruler of: Communication, Intelligence, & The Mind

Named for: The Roman Messenger of the Gods

Sign of Dignity: Gemini & Virgo

Sign of Detriment: Sagittarius

Sign of Exaltation: Virgo

Sign of Fall: Pisces

Physical Body: Brain, nervous system, lungs, arms, hands, tongue, bowels
Changes Sign: Every 3-4 weeks


Astronomy Quick Facts:

Type: Terrestrial

Length of Day: 59 Earth days

Length of Year: 88 Earth days

Moons: 0

Temperature: 430°C to -180°C

Colour: Dark Gray

Size: 4,879 km diameter (2.6x smaller than Earth)

Spins: Counter-clockwise

Rings: 0
Year Discovered: Known to the Ancients, ~265 BCE

About Mercury


Although he be but little, he is speedy! Named for the Roman Messenger of the Gods, Mercury is the smallest planet (aside from dwarf planet Pluto) in our solar system and the closest to the Sun. Mercury makes a lap around the Sun every 88 Earth days at an impressive speed of about 47 km/hour (29 miles/hour), but due to its extremely slow rotation on its axis (one rotation every 59 Earth days), there are less than 2 Mercurial days in 1 Mercurial year. Still, he remains the fastest planet in the solar system, true to his wing-footed namesake.

But don’t let his size fool you — Mercury is quick in more ways than one. Mercury is known as the Planet of the Mind, governing intelligence, communication, and mental activity. Its position amongst the stars influences the shifts in our thoughts and communications with one another from one day to the next. Mercury is known for its adaptability, fluctuations, and changeability, depending on his environment. Depending on the Zodiac sign Mercury is in on a given day, thought patterns can be quick, strict, and linear, or slower, creative, and intuitive. Mercury also rules the parts of the body that are integral to communication and self-expression, including the voice, the tongue, and the hands.

Because Mercury is never far from the Sun (within 28°), he is always placed in the natal chart in the same sign as the Sun, the sign directly before, or the sign directly after. Mercury’s placement in the natal chart speaks to the nature of an individual’s communication and the way the mind works:

  • For Fire sign Mercury, thought & communication is confident, outspoken, impulsive, opinionated, and direct.
  • For Air sign Mercury, thought & communication is quick, witty, rational, controlled, and erratic.
  • For Earth sign Mercury, thought & communication is practical, perceptive, logical, controlled, and analytical.
  • For Water sign Mercury, thought & communication is emotional, imaginative, intuitive, unfocused, and empathetic.

Mercury also oversees how we “communicate” with our environment: he is responsible for our flexibility and adaptability to our surroundings. Think of Mercury as the bridge between the brain and the nervous system; the way our bodies react to what the brain perceives and vice versa. As the ruler of the central nervous system, Mercury determines how quickly or slowly we act and react depending on what sign he resides in at the time. Since he moves so quickly through the signs, Mercury’s influence shifts often. Mercury retrogrades occur so often that it has become something of a joke in the astrology community. For 3 weeks, 3-4 times a year, Mercury goes retrograde, causing arguments, technological failure, and general misunderstandings.

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