Six Science posts #86

Lunar eclipse, "=" invention, start of the internet and more

Author

Harshal Chhaya
September 07, 2025

Six tweets that celebrate engineering and all things STEM.

I scroll so you don’t have to.

I was traveling last week and didn’t have an opportunity to send this newsletter.

(It wasn’t because the issue was 86’ed.)

Here’s a fun sign I saw in a coffee shop in Mumbai during my travels. Made me 😄 and think of you all.

Stay curious, friend!

#1 🤯 

The amazing coincidence that makes total eclipses possible: the Moon's diameter is 400 times less than the Sun's diameter, yet it is also 400 times nearer to Earth.

So they have the same relative size from our perspective! 😮 

#2 🤯 

Voyager 1 is a incredible feat of imagination and engineering.

It is still functional - nearly 40 years later 🤯 

#3 🤯 

The article at https://news.arizona.edu/news/asteroid-bennu-time-capsule-materials-bearing-witness-its-origin-and-transformation-over is fascinating reading.

“As the leftover materials from planetary formation 4.5 billion years ago, asteroids provide a record of the solar system’s history. But many of these remnants may be different from what meteorites recovered on Earth would suggest, Zega said, because different types of meteors (fragments of asteroids) may burn up in the atmosphere and never make it to the ground.”

#4 🤯 

Another great example of “you can just do things”.

If it makes sense, people will follow.

If not, eh…

#5 🤯 

Packet switching was such a unique concept back then. But the researchers persisted and the result is you reading this newsletter (among other things)

Honor their work by forwarding this to others. :)

#6 🤯 

Math teachers, do you agree?

This is issue #86. Let’s see what makes 86 an interesting number:

  • 86 is a happy number (think of Bob Ross painting “86” with his signature smile)

    • In number theory, a happy number is a number which eventually reaches 1 when the number is replaced by the sum of the square of each digit. For instance, 13 is a happy number because 1 2 + 3 2 = 10

    • 86 is a happy number because: 82 + 62 = 100 and 12 + 02 + 02 = 1

  • It is a semi-prime of the 2 * q form

  • It is the middle semiprime in the 85, 86, 87 cluster of semiprimes. The 2nd cluster of three consecutive semiprimes; the first comprising 33, 34, 35.

  • 86 is the atomic number of Radon - symbol Rn. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only 222 Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated. The instability of 222 Rn, its most stable isotope, makes radon one of the rarest elements. Radon will be present on Earth for several billion more years despite its short half-life, because it is constantly being produced as a step in the decay chains of 238 U and 232 Th

  • In American English, and particularly in the food service industry, 86 has become a slang term referring to an item being out of stock or discontinued, and by extension to a person no longer welcome on the premises.

  • 86 is the international calling code for Mainland China

  • 86 is the racing number of Chick Hicks — a character from Disney Pixar's “Cars” franchise.

  • x86 is the architecture developed by Intel for its chips that powered the PC revolution

About

This newsletter is my way of sharing interesting science-related news with my curious friends. I enjoy finding science and math connections in our world.

Please share this newsletter with others. Let’s encourage curiosity.

- Harshal (@hschhaya on X/Twitter)

That’s it for this issue.

Hit ‘reply’ to tell me what you think.

And hit ‘forward’ to share with your friends and family.

Let’s all celebrate science and engineering and curiosity.

Best wishes,

Harshal

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