OK, I get it, LIS was a corny and campy show even if it was sci fi. So, maybe I shouldn’t be too punishing to the show for its lapses in astronomy and physics.
But some of their blunders were pretty big! Although I loved the show dearly,
I hope the reboot does a better job in this department. Anyway here are some that I’ve caught over the years. Send me some more! I’ll go over what they got right at a future date.

..and Happy 50th Anniversary! (the show ended its run just about 50 years ago, in March of 1968.

OK, the biggest blunders:

1. Feeling Heat from Comets: In at least two episodes the Robinson’s claim they could feel the heat from an approaching comet. Comets are inherently very cold objects and very small. The only way they’d give off appreciable heat is if they were colliding with something or going through a planet’s atmosphere. I guess maybe that’s what’s going on in these episodes, but if so, they don’t mention it.

2. Getting Distances and Units of measure wrong: For instance, in one episode, Will Robinson claims that a parsec is 19.15 million miles. Wrong, Will. Its trillions, not millions! In the same episode (“Return from Outer Space”) he mentions that Alpha Centauri was 5.3 light years away (its closer to 4.3 light years away). It sounds like the writer lost his set of World Books Encyclopedias before this episode!

3. Confusing Galaxy, Solar System and Universe: This started in the very first episode when the Jupiter 2 was declared to have been leaving the Galaxy. Though this may have been what they literally meant, its more likely that they meant Solar System, since this all happened just after encountering what appeared to be our solar system’s asteroid belt. However, in later episodes they mention going to other galaxies. If that’s what they meant, then the physics is very wrong since even a faster than light ship wouldn’t be able to get to another Galaxy in such a short time (although maybe, if it was going MILLIONS of times the speed of light!).

4. Asteroids packed together: In reality, even an asteroid belt would have great distances between asteroids. Its exciting to see a ship bombarded by rocks constantly, but its unlikely a real ship in the real asteroid belt would experience that many collisions. However, at the very high speeds suggested by the show, even collisions with dust would be very damaging!

5. Gravity: OK, how the heck does their gravity simulation work? They don’t seem to be rotating, but such a small ship would have to rotate extremely rapidly to generate simulated gravity effects.

If you like this, you can see more in my book, The Physics and Astronomy of Science Fiction, available on Amazon and from other sellers.