Sense of Scale

A couple years ago, I saw a photo of Jupiter and Uranus, magnified the same, juxtaposed next to each other. Uranus was a dot down at the bottom next to Jupiter, pretty much a comparison of their view through the same telescope.

Until recently, Wikipedia's page on isotopes of hydrogen described an exotic atom called "hydrogen-4.1". The entry has since been moved to https://en.wikipedia.org/wiki/Exotic_atom.

Hydrogen-4.1 is helium with one electron replaced with a massive electron (over 200 times the electron's mass). The massiveness leads to its orbital radius being less than 1/200 the electron's orbital radius. With only one regular electron, this thing is chemically hydrogen -- really -- except that it lasts only a couple microseconds. The big circle is the electron orbital, and the dot at the center is the massive-electron orbital.

On the other hand, if the massive electron's orbital is the big circle, the helium nucleus is that dot in the center.