> This highly educated Engineering graduate student
> didn't know that they lived on a planet. Its ironic.
And assuming you're reasonably well educated, and reasonably well informed, and reasonably intelligent, you didn't know, or care, that "its" as you've used it should've had an apostrophe. When you write "Its ironic" the "Its" is an abbreviation of "It is".There are things that just don't matter in people's lives. For many, increasingly, traditionally "correct" usage of the apostrophe is one of them. For others, it is irrelevant that the word "planet" has a technical definition, that Jupiter and the Earth are examples, and Pluto no longer is.
Most people don't know that a sizeable proportion of the mass in wood comes from the air, or that the Earth goes round the Sun (in the simplest model of the Solar System) or that Google is not a web browser. These are things removed from people's concerns, irrelevant to them.
Before a few years ago I didn't know that Bach pre-dated Beethoven, even though I listened to their music all the time. Why should I care? No doubt I'd be laughed at by the self-declared "cultural" people, and then I'll ask them to quote the second law of thermodynamics.