It takes less than a minute for an astrologer to make some nonsensical claim, but far longer to explain why their claim is not justified. Not only is astrology fraud, it is theft too. Don't let them steal your time, copy and paste arguments from below...

Most physicists believe that there are four (and only four) fundamental interactions: gravitation, electromagnetism, the weak interaction and the strong interaction. None of these forces would allow astrology to work, as shown below.

1) Gravitation
The gravitational force of the moon on the earth is 100 times greater than that of Jupiter (the most massive planet in our solar system) whilst the tidal force of the moon is over 100,000 times greater.

2) Electromagnetism
The electromagnetic radiation from the sun or room lights is several degrees of magnitude more intense than that from any other celestial object.

3) Weak interaction
range: 10^-18m (0.1% of the diameter of a proton)

4) Strong interaction
range: 10^-15m (diameter of a medium-sized nucleus)

The combined gravitational pull of all the other planets in the solar system on the earth is about 1.7% of the gravitational pull of the moon, and the moon is only 1/81 the mass of the earth. The other planets really are an utter irrelevance!

In a civilized society we deplore all systems that judge individuals by sex, skin color, religion, national origin, or other accidents of birth. Yet astrologers boast that they can evaluate people based on another accident of birth - the positions of celestial objects. Isn't refusing to date a Leo or hire a Virgo as bad as refusing to date a Catholic or hire a black person?

A constellation is a miscellaneous set of stars all at different distances from us, which have no connection with each other except that they constitute a (meaningless) pattern when seen from a certain (not particularly special) place in the galaxy (here). A constellation is not an entity at all. The shape of a constellation, moreover, is ephemeral.
(adapted from:)
DAWKINS, Richard, The Real Romance in the Stars

Gravity figures:

"A baseball held at arms length has more tidal effect on you than Mars at its closest," Yeomans said in a telephone interview. "It's absurd to think that the alignment of a planet is going to have any significant tidal effect over and above the moon and the sun."
BRITT, Robert Roy, The End is Nigh -- Again: Scientists Say 'No Way' to Solar Tidal Doom

A mother holding her child "will exert 12 million times as much tidal force on her child as the moon" (Kelly et al., 1996, 25).

Astronomer George O. Abell claims that the moon's gravitational pull is less than that of a mosquito (Abell 1979).

Roger Culver and Roger Ianna, showed that the moon's "pull" was less than that of a wall of a building six inches away (see Culver and Ianna 1988).

The combined influence of the rest of the objects in the solar system is less than 10 billionths of the influence if the moon.
Nelson, J.H., "Shortwave Radio Propagation Correlation with Planetary Positions," R.C.A. Review, XII, No.1, (1951), 26.
Nelson, J. H.: "Shortwave Radio Propagation Correlation with Planetary Positions, RCA Review," (USA) March 1951, Vol. 12, pp. 26-34.
Nelson, J. H.: "Planetary Position Effect on Short Wave Signal Quality," Electrical Engineering, May 1952, Vol. 71, No. 5, pp. 421-4.

The Magus of Magnetism: An Interview With Dr. Percy Seymour
An Astronomer's Magnetic Theory of Astrology and How Planetary Motion Orchestrates Solar Activity and Geomagnetism by Bronwyn Elko

  • ADAMS, J., The Astroharmonic Debate

    [Danish site with references in English]
    Astrologisk Museum

    From Arch by Tana

    "Abstract. Solar activity, although virtually impossible to forecast a month in advance, has succumbed to scientific methods on long time scales, much as climate or seasonal weather predictions are simpler than weekly weather forecasting. Moderately accurate solar activity forecasts on decadal time scales now seem possible." Geophysical Research Letters : Electronic Version

    The Answer Man answers to questions by users of "From Stargazers to Starships"

    Planetary line-up and the sunspot cycle

    The Dynamic Sun Annals of the New York Academy of Sciences, Volume 98, pages 753-1326, October 30, 1962

    "Properties of Biological Rythms" by Sollberger
    Biological rhythm research / Arne Sollberger

    Brown's classic: "Extrinsic Rythmicality"
    Brown, F.A. (1962). Extrinsic rhythmicality: a reference frame for biological rhythms under so-called constant conditions.Annals New York Academy of Sciences 98, 775-787.

    Malek's work on Menstuation & Labor

    John Nelson: COSMIC PATTERNS

    Ravitz: "Periodic Changes in Electromagnetic Field"

    Leonard Ravitz

  • Ravitz, J. L., History, measurements, and applicability of periodic changes in the electromagnetic field in health and disease. Ann. N.Y. Acad. Sci. 98 (1962): 1144-1201.
  • Ravitz, L. J. (1982). History, measurement, and applicability of periodic changes in the electromagnetic field in health and disease. Ann. N.Y. Acad. Sci., 98, 1144-1201.
  • H. Burr, Blueprint for Immortality, Neville Spearman, London, 1971; cf. L. Ravitz, "History, Measurement, and Applicability of Periodic Changes in the Electromagnetic Field in Health and Disease", Annals, NY Academy of Sciences, 98:1144-1201, 1962. Another study concerning human energy fields was performed in 1959 by Dr. Leonard Ravitz at William and Mary University. Neurologist and psychiatric consultant Leonard Ravitz discovered a physiological connection between the moon and humans - involving man's electrical potential and the earth's magnetic field.
    [ Annals of the New York Academy of Science 96; 1181, 1960 ]

    Guarino did a Masters on Lunar Phase & Stock Prices at Pace Univ in NY

    Frank Guarino conducted a study entitled Relationship of the Stock Market to the Lunar Cycle as a requirement for an MBA at Pace University in the late 1970s. Guarino tested the rate of change in the DJIA between lunar phases from 1950 through 1973.

    Matlock's "MAN & COSMOS" is the most comprehensive analysis of Stock Price Movements with planetary and Lunar phenomena.

    Donald Bradley's STOCK MARKET PREDICTION (The Planetary Barometer and How to Use It)

    Michel Gauquelin

    Their representatives debated 3 top astro-researchers on David Suskind TV show in New York.

    Communal Reinforcement
    Communal reinforcement is the process by which a claim becomes a strong belief through repeated assertion by members of a community. The process is independent of whether or not the claim has been properly researched or is supported by empirical data significant enough to warrant belief by reasonable people.

    Selective Thinking
    Selective thinking is the process whereby one selects out favorable evidence for remembrance and focus, while ignoring unfavorable evidence for a hypothesis. 'The moon was full and nothing happened,' may be accurate but it is not a very interesting headline.

    Confirmation Bias
    Confirmation bias refers to a type of selective thinking whereby one tends to notice and to look for what confirms one's beliefs, and to ignore, not look for, or undervalue the relevance of what contradicts one's beliefs.

    Self-deception is the process or fact of misleading ourselves to accept as true or valid what is false or invalid. Self-deception, in short, is a way we justify false beliefs to ourselves.

    "The acceleration due to walking would create gravitational effects of far greater magnitude than those caused by the Moon and Sun combined,"

    Tidal Forces of the Sun, Moon, and Planets on the Earth
    (The sun's tidal force equals 1.00)
    ref: Thompson, 1981
    moon 2.1
    sun 1.00
    Venus 0.000113
    Jupiter 0.0000131
    Mars 0.0000023
    Mercury 0.0000007
    Saturn 0.0000005
    Uranus 0.000000001
    Neptune 0.000000002
    Pluto 0.0000000000001