Look at This 70 Year-Old Astronomy Book!

The oldest astronomy book in my collection was printed in ’52, called Teach Yourself Astronomy by David Evans, and despite it being outdated it contains a lot of extremely valuable information for the amateur astronomer!

Let me show you some of the most interesting parts!

This part of the book, Fundamentals, talks about coordinates, the celestial sphere; essentially familiarising yourself with the night sky. The diagrams are super helpful, and actually this book is how I first understood hour angles and right ascension.

The First Point of Aries, similarly to the prime meridian in longitude, is just an arbitrary point. I can’t believe it took me so long to … just … get it.

The fundamentals chapter also talks about terms such as zenith & horizon. It teaches you how to locate stars, how to estimate degrees with your hand, and most impressively how to use a sextant!

These next 2 are just interesting bits of outdated-ness!

Now while the book is correct in the literal definition of the astronomical unit, the numerical definition isn’t. 1 AU here is defined as 93’005’000 miles, but today (in 2021) we know it to be 92’956’000 miles! Woa!

I won’t pick apart every bit of outdated stats here (and a lot of it is still correct as of now), but I wanted to point out the little question marks under the Period of Rotation column. Mercury’s day is way off it’s actual sidereal day (58.6 days), and Venus’ sidereal day is actually 243 Earth days. Can you even believe these discrepancies?

There isn’t even a number for poor little Pluto! It’s actual day is about 6.4 days, but I thought it’s cool to know that the information we have about the planets isn’t even a lifetime old!

Below is my favourite! As expected, a lot of these numbers are incorrect as of today, but that’s not what I want to discuss. By the time this book was published, only 12 of Jupiter’s 80+ moons had been discovered! The footnote below the table is actually talking about Ananke, but the author didn’t know that at the time!

It’s also interesting how only 2 of Neptune’s 14 satellites had been discovered at this point. Triton and Nereid had been previously discovered by Lassell and Kuiper respectively, but the latter satellites would have to wait another 29 years after this book to be discovered!

That’s all for this week! I’ll finish this post with some beautiful plates in this book. The left ones are clusters of stars, and the plates on the right are solar observations.


    • Woa, you’ve experienced so much advancement in space exploration! Amazing to think that a lot of information in the book would have been hard facts when you were younger!


    • I was surprised but also not surprised to see them. I think I expected to see just categorically incorrect info, but even astronomers at that time still admitted they didn’t know everything!


  1. Astronomy has a very, very long history. That’s one of the things I love about it. Looking out into space makes me think about the future, for obvious reasons, but it also makes me feel more connected to the past.

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