You may have heard of a common pseudoscience—astrology. Astrology is a pseudoscience because it’s a set of beliefs that seem to be based on scientific ideas, but really, it fails to obey even the most basic rules of science.

What are the basic rules of science, then?

The absolute most basic rule of science is that any claim must hold up to tests before it is adopted as “truth.” For example, you can test whether a plant grows from a seed by planting one and watching what happens.

In this case, the “test” is watching the plant grow in conditions where you can be around to observe it. You accept it as proven and true when the plant grows from the seed as predicted, time after time.

Of course, there are times when the plant doesn’t grow from the seed. But those times just tell us that there’s a chance germination, as it’s called, won’t work.


Astrology is far from the only pseudoscience. In the 1970s, there was a claim that pyramidal shapes focus energy from the cosmos on anything underneath, and even have healing properties.

The people who believed this even suggested that pyramids made out of different materials could preserve fruit, sharpen razor blades, and do other miraculous things.

Several tests were performed to confirm this belief. It was found that absolutely any shape protects food from airborne spores and allows it to dry without rotting. And any shape can allow oxidation to sharpen the cutting edge of a razor blade.

The belief that pyramids had more powers than any other shape could have survived as a form of religion, but the people making the claim insisted it was a science long after science itself proved their claim untrue. That makes this a pseudoscience.

Is it possible that some cosmic force touched these pyramids and gave them miraculous powers? Absolutely. But that belief would be a religious one, not a scientific one.

Any belief that claims to be based on science but doesn’t hold up to scientific tests is a pseudoscience, not a real science.

Astrology is one such pseudoscience, and it’s possibly the oldest one. It’s actually based on the ecliptic, the apparent path of the sun across the background of constellations in the sky.


If you’re familiar with astrology, you’ll notice the constellations along the ecliptic shown here as the signs of the zodiac. Have you ever noticed that people who were born in August, “under” the sign of Leo, don’t actually see Leo in the night sky that month?

That’s because Leo the Lion, a constellation, is on the other side of the planet on August nights. If the sun weren’t so bright, we would see Leo during the day—and the sun would appear right in the stars of Leo.

An important part of astrology is the zodiac, a band around the sky extending 9° above and below the ecliptic. The constellations along the ecliptic are known as “signs” of the zodiac, and when we say we were born “under” one of them, we mean that the sun appears “in” that constellation during our birthday month.

All this is true. It’s inaccurate to call constellations “signs” and to say we were born “under” one of them, but the sun does pass through these constellations. So why is astrology a pseudoscience?

I could spend hours picking out examples across the web of what makes astrology absolutely unprovable by scientific means. But here are just a few examples.

Astrology uses “horoscopes” to predict people’s personalities and lives by what “sign” they were born under.

Horoscopes, put simply, are just diagrams showing where the sun, moon, and planets are at any given time. They all stay close to the ecliptic, so they are always somewhere in the zodiac.

Because the planets are named after Greek and Roman gods, horoscopes use the roles of the gods themselves to guess at people’s personalities and predict upcoming events in their lives.

Some people genuinely believe in astrology and are interested in horoscopes. I don’t begrudge you if you do. My only point is that it is not a science; it’s a pseudoscience.

As an example, let me punch a hole in one of astrology’s theories. Above, the signs of flirting are listed for all twelve zodiac signs. Leo is claimed to be the one that makes everyone else blush. It seems to me that Leo is generally pretty straightforward…


But I’m Leo. And I’m none of those things.

I was born in August, when the sun was passing through Leo. But I’m not the sort of person who says things when I shouldn’t. In fact, I take my cue from others. I’m not a leader and don’t even feel like one, contrary to some depictions of Leo.

But I’m like Leo in some ways, you might say.


Yes, sometimes I pretend to be okay with things that I’m upset about. In fact, I do that all the time.

When my family gave away my horse in favor of paying for college, a choice I wholeheartedly agreed with, we never quite got around to giving me a chance to say goodbye to her. I accepted it and moved on.

Yes, it upset me. Yes, I would rather have been able to hug Munchie goodbye. But what’s the point in dwelling on it? It’s in the past. I can pretend not to be upset.

But here’s the thing. I may be like Leo in that way, but I’m also like Scorpio up above. If I find out someone’s crushing on me, I most definitely keep it G-rated.


And here, I’m like Aquarius. Hearing someone’s crushing on me gives me a mechanical read error. I immediately panic and think, “How on earth am I supposed to even answer?”

I’m not going to bore you with a discussion of my (nonexistent) love life. My point is that I just punched a hole in astrology. I just showed that its claims aren’t necessarily true, if you think about them scientifically.

I could spend hours asking scientists how they align with the signs, and showing you how many people can have qualities associated with several different signs.

But does any of that matter? No.

Astrology is a pseudoscience because no matter how many holes you punch in its beliefs, it doesn’t correct or abandon them. It claims to be a science, but it’s not. And there’s nothing I can say scientifically that will change astrology.

Because astrology is a pseudoscience, and it stands strong in the face of opposing evidence.

If you believe in astrology, go for it. If you pay attention to the signs of the zodiac, by all means, do as your heart desires! But be aware that there is a strong distinction between science and pseudoscience.

And please don’t confuse astrology with astronomy. They’re as different as night and day. Astrology is a pseudoscience; astronomy is the science that helps us understand the universe. Astrology is a set of beliefs; astronomy is a set of theories and evidence.

Astronomy, rather than astrology, is covered in depth on this blog.

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