Harvard's CS50 does a great job at this. My first intro to CS was through this course, and I'm grateful I did it this way rather than wait till I was taught in the "broken" way at college.
In many workplaces, you're required to use the company provided email address with git. And the name some people use at work isn't the same as what they use in their personal projects. (For ex, I use my full name at work but a shorter one for personal stuff)
I looked it up, turns out it could be any of those depending on how big it is, how far it is, and what its peak brightness here. [1] does a good job of explaining it
Yep. Something fishy about got defensive the replies are. Besides, its not just an idea from a "random inter Blog from 6 years ago", Tim Urban also shows it in his popular Ted(x) talk