Book summary “Bad astronomy”: summary

Introduction

You encounter scientific falsehoods every day in news reports, films, and casual conversations. These persistent myths range from harmless household superstitions to elaborate space conspiracy theories that obscure how the universe actually works. When bad science goes unchallenged, it erodes critical thinking and replaces wonder with fear or confusion.

Philip C. Plait steps in to dismantle these common misconceptions through clear observation and rigorous scientific reasoning. The central idea of the book is that understanding how the cosmos operates requires you to look past cultural myths and examine the physical evidence yourself.

The book guides you through a broad survey of cosmic errors. You will explore terrestrial physics, lunar illusions, celestial mechanics, and media fiction. Along the way, the text addresses several core questions:

• Why do water drains spin the wrong way during an equinox?
• How do movies consistently break the laws of physics for dramatic effect?
• What evidence disproves the notorious Apollo moon landing hoax?

1. Bad Astronomy Begins at Home

You might believe that a chicken egg can only be balanced on end during the spring equinox. The legend claims that a special alignment of gravity between the Earth, Sun, and egg occurs only on the vernal equinox, allowing the egg to balance.

The widespread belief that a chicken egg can only be balanced on end during the spring equinox is completely false.

In reality, an egg can be balanced on its end at any time of the year. Roughly 130 million people in America have heard of or tried the egg balancing ritual. During formation, an egg sits in the chicken's shell gland for approximately 20 hours.

Philip Plait successfully balanced seven eggs on end in his kitchen in autumn, months away from the vernal equinox. Later, students at Mancelona Middle School balanced eggs on their narrow tips in October and left them standing for over a month.

Egg Balancing

You can test this physical property yourself:

• Find a carton of chicken eggs.
• Select an egg that has small calcium bumps on its bottom end.
• Exercise patience, care, and a steady hand to upend and balance the egg on a flat surface.

The egg-balancing ritual originates from a misinterpreted traditional Chinese festival reported in the media rather than any astronomical event. Life magazine published an article on March 19, 1945, written by Annalee Jacoby, about a Chinese ritual practiced on Li Chun, the first day of spring in the Chinese calendar. This date falls roughly six weeks before the vernal equinox. The United Press picked up the story, and later media figures like Donna Henes promoted it widely in New York City. In 1983, ritual-maker Donna Henes gathered about a hundred people at the World Trade Center to publicly stand eggs up at the exact moment of the vernal equinox, an event covered by the New Yorker and later mistakenly endorsed by the New York Times. More than five thousand people showed up at the World Trade Center for an egg balancing event in 1984.

The Coriolis Effect

You may also think that the Coriolis effect determines the direction water spins when it drains from your sink or bathtub.

The Coriolis effect is a real meteorological phenomenon caused by the Earth's rotation, but it is far too weak to influence small bodies of water like sinks, bathtubs, or toilets.

As latitude increases from the equator, the eastward velocity of the Earth's surface decreases, causing moving objects and air masses to deflect. A point on the equator travels 40,000 kilometers or 25,000 miles in one day at an eastward speed of 1,670 kilometers per hour or 1,030 miles per hour. While this effect creates large-scale systems like hurricanes over vast distances and long periods, random eddies and the specific shape of a basin entirely overwhelm the minuscule Coriolis force in household drains. A car driving north at 100 kilometers per hour in Wiscasset, Maine, is deflected by the Coriolis effect by a tiny amount of 3 millimeters or 0.1 inches per second, amounting to a total deflection of only 10 meters or 33 feet after a solid hour of driving.

Tourist demonstrations showing water draining in opposite directions across the equator are deliberate swindles. Street demonstrators near the equator in places like Nanyuki, Kenya, fake the Coriolis effect by using a square pan approximately 30 centimeters in width and introducing rotational momentum. When they walk to one side of the equatorial line and pull the plug, they subtly spin the pan in the required direction to force the water to swirl clockwise or counterclockwise. Peter McLeary demonstrates water draining in opposite directions across a painted line in Kenya for tourists, a trick also featured on the PBS series Pole to Pole hosted by Michael Palin.

2. Misconceptions in Language and Optics

Everyday idioms and atmospheric scattering create persistent optical and linguistic illusions.

Astronomical Terminology

A light-year is a unit of distance, not of time or speed. Misunderstandings of astronomical terms often lead to improper uses in advertising and media, where light-years are mistakenly used to denote speed or advanced time, whereas astronomers use it strictly as the distance light travels in one year. Light travels at 300,000 kilometers per second, and a light-year spans about 10 trillion kilometers. Proxima Centauri sits 4.2 light-years away, while a parsec equals 3.26 light-years. In Star Wars, Han Solo claims to make the Kessel Run in less than 12 parsecs, treating a distance unit like a time unit.

Small space debris orbiting the Sun is called a meteoroid; when it enters the atmosphere and glows from friction, it is called a meteor; if it survives to hit the ground, it is called a meteorite. The Moon does not have a permanent dark side; it has a far side that experiences day and night. The Moon rotates synchronously with its revolution around Earth, always showing the near side to us and hiding the far side. Because the Moon spins, its far side periodically experiences sunlight, making the phrase dark side an inaccurate synonym for the far side. Pink Floyd's famous album Dark Side of the Moon reinforces the misconception, though a voiceover at the end notes the Moon is generally dark like slate.

A quantum leap describes an electron jumping between discrete atomic energy levels rather than a massive bound. In quantum mechanics, electrons are restricted to specific orbital steps like a staircase and must absorb an exact amount of energy to jump to the next level. While the actual distance of this jump is 0.00000000001 centimeters, the phrase aptly captures a sudden, major advance skipping intervening space. Advertisers use the term quantum leap to boast that a product is vastly superior to competitors.

Why the Sky Is Blue

The sky is blue because atmospheric molecules scatter short-wavelength blue light more efficiently than red light. Sunlight is composed of all colors of the spectrum. Nitrogen and oxygen molecules in the atmosphere act like bumpers, scattering blue photons in all directions via Rayleigh scattering, which makes the sky appear to glow blue from every angle.

Shining a bright white flashlight through a glass of water mixed with a few drops of milk demonstrates light scattering, turning the beam redder when viewed straight through and bluer from the side. You can test this effect easily:

• Get a glass of water and put a few drops of milk in it.
• Mix in the milk, then shine a bright white flashlight through the mixture.
• Observe the beam from the opposite side to see it look redder, and from the side to see the milk look bluer.

Sunsets appear red and orange because sunlight travels through a thicker layer of atmosphere, scattering away blue and yellow light. When the Sun is on the horizon, its light passes through a much greater path of air than when it is overhead. Volcanic eruptions inject particles into the atmosphere, amplifying scattering effects and producing spectacular sunsets for years afterward.

The seasons are caused by the tilt of the Earth's axis, not by changes in the Earth's distance from the Sun. The Earth's orbit is elliptical, but the resulting distance variation causes only a minor temperature shift of 4 degrees Celsius. The primary driver of seasons is the 23.5-degree axial tilt, which changes the concentration and angle of sunlight hitting different hemispheres throughout the year. Seasonal variation causes a 44 degrees Celsius temperature change in places like Maine.

Shining a flashlight straight down onto a piece of paper versus tilting it at a 45-degree angle demonstrates how tilting spreads out the light and reduces its heating efficiency. You can observe this geometry at home:

• Darken the lights in a room and take a flashlight and a piece of white paper.
• Shine the flashlight straight down on the paper to see a bright circle of light.
• Tilt the paper so that the light shines down at about a 45-degree angle to observe the light spread out into a dimmer oval.

Earth's axis precesses in a slow wobble caused by the gravitational tug of the Moon. Acting like a spinning top influenced by gravity, the Earth's axis traces a 47-degree circle in the sky over a 26,000-year precession cycle due to the off-axis torque exerted by the Moon. This wobble gradually shifts which star serves as the North Star and slowly alters the timing of the seasons relative to the Earth's closest approach to the Sun. The northern axis currently points toward Polaris, but around 2600 B.C. it pointed toward Thuban and around A.D. 14,000 it will point near Vega.

3. The Moon and Stars

Lunar phases and stellar twinkling reveal the interplay between geometry, psychology, and our atmosphere.

Phases and the Moon Illusion

The phases of the Moon are caused by its orbit around the Earth changing our perspective of its sunlit half, not by Earth's shadow. The Moon is a sphere where half is always illuminated by the Sun and half is in shadow. As it orbits our planet once a month, you see different portions of the lit hemisphere, categorized as New Moon, First quarter, Full Moon, Third quarter, Waxing, Waning, and Gibbous.

An imagined demonstration using a styrofoam ball for the Moon, a lamp for the Sun, and yourself as the Earth shows how different angles reveal crescent, half, or full phases.

A full moon is up to ten times brighter than a first-quarter moon due to the lack of shadows and a special light-reflecting property of lunar soil. When the full moon occurs, sunlight shines straight down, eliminating surface shadows that would otherwise darken it. Additionally, meteorite impacts and radiation have ground the top centimeter or so of the lunar surface into a fine powder that exhibits back-scatter, reflecting light directly back toward the light source.

The faint glow seen on the dark portion of a crescent moon is caused by sunlight reflected off the Earth. Earth goes through phases opposite to the Moon's as seen from the Moon. A brightly lit Earth reflects sunlight onto the dark part of the lunar surface, an effect enhanced when clouds cover the Earth. Poetically called The old Moon in the new Moon's arms, this earthshine allows viewers to spot lunar craters using binoculars.

The Moon illusion—making the horizon moon look two to three times larger—is a psychological effect rooted in how our brains perceive the flattened shape of the sky and apply size constancy. Physical distance and atmospheric magnification do not cause the illusion; in fact, the moon is slightly further away on the horizon. Instead, the brain perceives the sky as an inverted bowl that is farther away at the horizon, and combined with the Ponzo illusion and size constancy, it interprets the horizon object as larger. Psychologists Lloyd and James Kaufman projected two images of the moon and found subjects perceived the horizon moon's distance as four times greater.

You can test this illusion directly using a simple method:

• Go outside to level ground with a clear view.
• Imagine a line from the zenith to the horizon.
• Point your arm to where you think the 45-degree halfway point is.
• Have a friend measure the angle to find it is usually around 30 degrees.
• Bend over and look at the horizon moon upside down from between your legs to verify the illusion vanishes.

Accounting for geometry, the average distance to the Moon is 400,000 kilometers, with a 40,000 kilometers difference between perigee and apogee. The Moon is 6,000 kilometers closer when overhead, giving it a 1.5 percent bigger appearance when overhead compared to the horizon.

Stars and Telescopic Correction

Stars twinkle because turbulent, moving cells of air in Earth's atmosphere randomly bend starlight. As steady starlight passes through atmospheric temperature layers and cells of air a few dozen centimeters across, each cell refracts the light slightly in random directions, making the star's tiny image jump around so your eyes perceive a dance. Typical seeing yields a couple of arcseconds of blur, compared to the 100 arcseconds naked-eye resolved disk limit and half an arcsecond for the best planetary seeing.

Planets generally do not twinkle like stars because they appear as disks rather than point sources through a telescope. Although planets are physically smaller than stars, they are much closer, forming an apparent disk in the sky. While atmospheric turbulence affects the disk, the motion averages out across its size, keeping the planet relatively steady. Jupiter is seen as a disk with just a pair of binoculars.

Adaptive optics technology corrects for atmospheric blur by physically warping telescope mirrors in real-time. By measuring atmospheric distortion, systems use pistons and actuators behind a flexible mirror or segmented mirrors to distort the glass just enough to counteract seeing changes, rivaling space-based telescope clarity. Images from the 3.6-meter telescope at Canada-France-Hawaii and the 8-meter, hexagonally segmented mirror for the Very Large Telescope demonstrate how binary star pairs shift from an amorphous blur to distinct points when adaptive optics are activated at 0.3 arcseconds separation.

The color and light emission of a star depend directly on its surface temperature as governed by quantum mechanics.

Nuclear fusion at stellar cores generates millions of degrees of energy that travels to the surface, where temperatures reach a few thousand degrees Celsius to peak the frequency of emitted photons. Max Planck solved blackbody radiation by introducing quantized energy packets, which led to the foundation of quantum mechanics and Einstein's later work on the photoelectric effect, compared to a 22 degrees Celsius room temperature on Earth and 40 trillion kilometers to the nearest star besides the Sun.

Faint stars appear white to the naked eye because their light is too dim to trigger the color-detecting cone cells in human retinas. Human eyes use sensitive rod cells for brightness and less sensitive cone cells for color differentiation. Dim stars activate rods, making the star visible as a white point, but require a telescope to collect enough light to reveal their true colors through activated cones. The bright star Vega, which is the fourth-brightest star in the night sky, reveals a brilliant blue sapphire color through a telescope, delighting home-schooled students viewing it for the first time.

4. Eclipses, Alignments, and Space Rocks

Cosmic alignments and meteor impacts are routinely exaggerated by fear and scientific illiteracy.

Eclipses and Sun-Watching

Looking at a partial solar eclipse is more dangerous than looking at the uneclipsed sun because darkness during totality causes pupils to dilate, letting concentrated ultraviolet and blue light damage the retina. Under normal conditions, bright light causes the pupil to constrict and protect the eye, making glancing at the uneclipsed sun generally safe from permanent damage. During an eclipse, the darkened sky dilates the pupil, and when the bright solar sliver reappears, unprotected harmful blue light floods the retina and triggers photochemical damage.

A young woman from Bosnia told the author about streets deserted during the August 1999 solar eclipse due to alarming rumors of fatal rays.

You can protect your eyes during solar observation using specific safety measures:

• Use a telescope or binoculars to project the image of the sun onto a piece of paper or a wall.
• Wear very dark goggles rated as #14 like those used by welders.
• Use a solar filter that mounts strictly in front of the main lens or mirror.

Galileo Galilei projected the sun's image through his telescope onto paper or walls to safely study sunspots and avoid direct eye damage. Galileo did not go blind from observing the sun through his telescope, as he utilized a safe projection method and later suffered from age-related conditions like cataracts and glaucoma. In 1503 during his fourth voyage, a stranded and desperate Columbus used his knowledge of an upcoming lunar eclipse to terrify native Jamaicans into continuing to provide food and shelter by threatening to make the moon disappear.

Planetary alignments cannot trigger terrestrial disasters because planetary gravitational and tidal forces on Earth are entirely negligible compared to the Moon. Doomsayers and authors like Richard Noone and John Gribbin popularized false claims that the May 5, 2000 planetary alignment or 1982 Jupiter Effect would shift poles or destroy Los Angeles. During the Grand Alignment on May 5, 2000 at 8:08 A.M. Greenwich Time, planets were distant and often on the far side of the sun. Distance reduces gravitational and tidal forces drastically, making the combined gravitational pull of all the planets vastly weaker than the gravitational pull of a person sitting next to you or the tiny Moon.

Meteors and Asteroids

Space rocks are classified into three distinct terms based on their location and flight stage: meteoroids in space, meteors as luminous streaks in the atmosphere, and meteorites if they reach the ground. Meteoroids originate from comets or asteroids. When entering the atmosphere at extreme velocities up to 100 kilometers per second, they compress the air in front of them, creating a standoff shock that heats and melts the surface via ablation rather than simple frictional rubbing.

David and Donna Ayoub experienced a mysterious object landing and starting two small fires in their Salisbury, New Hampshire backyard on December 4, 2000. David and Donna Ayoub's backyard fire in Salisbury was investigated by the author, who concluded it was caused by terrestrial sources like fireworks rather than a meteorite. Small meteorites do not cause fires upon landing and are often remarkably cold or covered in frost because atmospheric heating affects only their outer layers briefly.

Because meteoroids spend billions of years in frigid deep space and traverse the atmosphere quickly while ablating their hot outer material, the intense heat never penetrates their insulating rocky interiors. The minutes taken to fall through cold lower air further cool them down.

Blowing up threatening large asteroids with nuclear weapons is counterproductive, whereas deflecting them via solar sails or controlled nuclear vapor blasts is scientifically viable. Hollywood films like Armageddon and Deep Impact popularized scientifically inaccurate methods like drilling and blowing up massive asteroids. Fragmenting a moderately sized asteroid multiplies devastation by spreading multiple impacts across the planet. Instead, attaching solar sails to catch solar wind, or detonating a small nuclear device a few kilometers above the surface to vaporize material and push the asteroid like a rocket, provides a safe deflection strategy.

5. Cosmology and the Moon Landing Hoax

The expanding universe gives the false illusion that we are at its center, just as passengers in expanding movie theater seats would all perceive themselves to be the center of the movement.

Edwin Hubble discovered that distant galaxies are receding from us, with more distant ones moving faster. This resembles an explosion, but similar to rows of seats moving apart in a theater, every observer in any galaxy would measure the exact same pattern of recession, meaning there is no privileged center in the universe. Space is a tangible fabric that can be warped by mass and can possess distinct geometries such as flat, open, or closed. Einstein recognized that space is not just an empty container but a physical fabric that gets distorted by mass, producing gravity. Depending on this curvature, space can be flat, closed, or open, and its geometry can be determined by measuring the angles of massive triangles. Karl Friedrich Gauss attempted to measure big triangles from three hilltops to test the universe's geometry, though the scale was too vast to definitively measure.

The expanding universe and historical space missions are frequent targets of unfounded conspiracy theories.

Debunking the Moon Landing Hoax

The absence of stars in Apollo moon photographs is actually proof of their authenticity, as short camera exposures tuned for a bright spacesuit cannot capture faint starlight. Hoax believers argue that a black lunar sky should reveal thousands of stars. However, because the lunar landscape and spacesuits are intensely illuminated by the Sun, astronauts used very short camera exposure settings, which fail to register faint background stars. Taking a photograph at night on Earth using the exact same camera settings as the Apollo astronauts yields a completely black sky with no visible stars.

Astronauts safely survived the radiation of the Van Allen belts by traversing them quickly along a trajectory that minimized exposure. Conspiracy theorists claim the intense radiation of the Van Allen belts would kill any human passing through them. NASA protected the astronauts by selecting a trajectory that only nicked the inner belt and spent minimal time in the region, while metal spacecraft walls shielded against particle radiation. Explorer 1 discovered the radiation zones in 1958, revealing charged particles trapped by the Earth's magnetic field.

The lunar module did not leave a massive blast crater or blow away all surface dust because its descent engine was throttled down and airless mechanics differ from Earth. Critics argue a 10,000-pound thrust engine should have dug a deep crater and cleared all dust. In reality, the engine was throttled down to about 30 percent thrust upon landing, spreading the pressure over a large nozzle area. Furthermore, without air to displace, dust was only blown directly beneath the exhaust plume. Apollo 11 pilot Neil Armstrong noted that moving dust proved difficult for gauging lateral speed, while Buzz Aldrin commented on picking up dust during descent.

6. Velikovsky and Creationism

Catastrophic historical claims and creationist physics fail when tested against rigorous scientific principles.

Velikovsky's Planetary Theories

Immanuel Velikovsky claimed in Worlds in Collision that Venus was ejected from Jupiter around 1500 B.C. and careened near Earth and Mars, causing ancient catastrophes. Such an ejection would require energy that would have literally vaporized Venus into incandescent gas rather than forming a solid roaming planet.

Comparing the scenario to dropping an anvil on an egg and expecting two neat halves with separated white and yolk, you can see that forces of that magnitude do not clean up so neatly. Harvard astronomer Harlow Shapley wrote vitriolic letters to Macmillan warning that publishing Velikovsky would damage the publisher's reputation for selling textbooks.

For Venus's atmosphere to have exchanged with Earth's, Venus would need to pass within 1,000 kilometers of Earth's surface. This proximity would produce kilometers-high ocean tides, completely sterilize the Earth's surface through earthquakes, and either fling the Moon into interplanetary space or severely distort its orbit.

The Hebrew calendar, active for nearly 5,800 years and spanning the time of the alleged disasters 3,500 years ago, shows no measurable change in the Moon's orbital period.

Creationist Astronomy Fallacies

Creationist Don DeYoung argued that dividing the Earth-Moon distance by the current annual recession rate of 4 centimeters yields an impossibly young age for the Moon. However, tidal friction and gravitational interaction rates vary over time, and the past recession rate was slower.

Apollo astronauts left reflectors on the lunar surface, enabling Earthbound astronomers to precisely measure that the Moon's distance increases by about 4 centimeters per year.

Creationists argue that inner planets should share the Sun's high hydrogen and helium composition if they evolved from the same cloud. The solar nebula disk had a temperature gradient, evaporating ice near the center while preserving it outward.

Flicking a small pebble sends it flying, while flicking a heavy station wagon does not move it. Light hydrogen atoms receive enough kinetic energy during collisions to escape Earth's gravity, whereas massive, cold outer planets retain them over 4.55 billion years.

Creationist Keith Davies argued that because no supernova remnants are older than 10,000 years, the universe must be young. This argument ignores the fact that supernova remnants occur at the end of a massive star's life after millions of years of evolution.

7. UFOs, Astrology, and Hubble

Psychological biases and optical limits explain persistent beliefs in UFOs, astrology, and flawed telescope narratives.

UFO Misconceptions

At Cape Canaveral in 1997, Plait and his family watched glowing dots move slowly in the sky before realizing they were terrestrial waterfowl illuminated by shuttle pad spotlights. Even trained astronomers can temporarily misidentify ordinary phenomena as mysterious flying objects due to unusual viewing conditions.

The planet Venus is the single largest source of UFO sightings because its extreme brightness and atmospheric distortion make it appear as a massive, flickering disk. Plait frequently receives e-mails from people asking about huge objects in the sky that invariably turn out to be Venus.

During Space Shuttle mission STS 48 in 1991, night-sensitive cameras recorded floating specks of light changing trajectory after a flash from a vernier rocket control burst. Physics teacher Dr. Jack Kasher argued that this footage showed alien spacecraft dodging missile fire, selling a video analyzing the footage for $29.95 plus shipping and handling.

Astrology and Hubble

A website attempting to justify astrology through gravity ignores the fact that Mars' gravitational influence drops by a factor of over fifty when it moves from one side of the Sun to the other. According to a 1984 Gallup poll, 55 percent of American teenagers believed in astrology despite its lack of fundamental physical mechanisms.

Media outlets like CNN and PBS repeatedly make the technical error of referring to the Hubble telescope as operating through a lens instead of a mirror. Large telescopes utilize mirrors instead of lenses because mirrors avoid chromatic aberration, are easier to support from behind, and require grinding only a single surface.

Astronaut Steve Hawley released Hubble into orbit in April 1990 using the Space Shuttle robot arm from an altitude of about 600 kilometers. The Hubble Space Telescope cost an estimated $6 billion and features a primary mirror measuring 2.4 meters across.

8. Hollywood Physics

Major motion pictures routinely sacrifice scientific accuracy for cinematic spectacle.

Bad Astronomy in Movies

You see sci-fi movies feature roaring engines and explosions in space, ignoring the physical requirement of an air medium for sound propagation. Because space is a vacuum, sound waves cannot propagate, though shock waves can theoretically travel through dense interstellar gas clouds. Gene Roddenberry originally wanted the starship Enterprise to move silently in Star Trek, but network executives forced the addition of a rumble and whoosh.

Commercial star-naming companies sell certificates and map coordinates, but their star designations are entirely unofficial and unrecognized by professional astronomers. The International Astronomical Union is the sole official body for naming celestial objects. Stars are designated by their position, coordinates, or catalog numbers rather than personal names sold by private registries. The author's brothers bought him a star from the International Star Registry for his birthday, which is actually cataloged as BD+48° 683 in the German Bonner Durchmusterung catalog. ISR charges a typical fee of $50 to $100 for a star name. The German Bonner Durchmusterung catalog lists 300,000 fainter stars, while an ISR website claimed an overly precise and incorrect number of 2,873 naked-eye stars.

10 Key Ideas

1. The widespread belief that a chicken egg can only be balanced on end during the spring equinox is completely false.
2. The Coriolis effect is a real meteorological phenomenon caused by the Earth's rotation, but it is far too weak to influence small bodies of water like sinks, bathtubs, or toilets.
3. The sky is blue because atmospheric molecules scatter short-wavelength blue light more efficiently than red light.
4. The seasons are caused by the tilt of the Earth's axis, not by changes in the Earth's distance from the Sun.
5. The phases of the Moon are caused by its orbit around the Earth changing our perspective of its sunlit half, not by Earth's shadow.
6. Looking at a partial solar eclipse is more dangerous than looking at the uneclipsed sun because darkness during totality causes pupils to dilate, letting concentrated ultraviolet and blue light damage the retina.
7. Planetary alignments cannot trigger terrestrial disasters because planetary gravitational and tidal forces on Earth are entirely negligible compared to the Moon.
8. The expanding universe gives the false illusion that we are at its center, just as passengers in expanding movie theater seats would all perceive themselves to be the center of the movement.
9. The absence of stars in Apollo moon photographs is actually proof of their authenticity, as short camera exposures tuned for a bright spacesuit cannot capture faint starlight.
10. A website attempting to justify astrology through gravity ignores the fact that Mars' gravitational influence drops by a factor of over fifty when it moves from one side of the Sun to the other.