I can just go outside and observe...
No, sorry, we call that rehearsing your prejudices.
Where you have already made up your mind about Flat Earthers, and you talk yourself through that conclusion. That's what Round Earthism is. A presupposition that already decides the Earth is round, and ignores any observation to the contrary.
Like observing earth’s natural satellite the moon.
Which cannot maintain a fixed and regular orbit to a moving object. If you actually thought about this instead of rehearsing, you would realize that given multiple vectors of motion, the moon's position cannot be the same from night to night. Instead, the sun an moon have predictable patterns since that they most certainly have to be pulled around a fixed central surface.
Or the moons of Jupiter
A wandering star pulling other wandering stars. The planets are powerful angels who swore disobedience to God's will. As I refuse idols, tuning the planets out is what I have decided to do.
Or try to predict a comet
More astrological idolatry. Even professional astronomers don't feel like watching a comet night after night.
When comets are first seen through a telescope, they are faint, "fuzzy" patches of light at the limit of visibility. A few years ago, most comets were discovered by amateur astronomers who looked for comets as a hobby.* To find comets takes enormous patience and many nights of scanning the sky through huge binoculars or wide angle telescopes. To save time, amateur comet hunters also memorize large areas of the sky, so that they can immediately recognize when something new appears. Recently, professional astronomers have discovered many comets. Professionals normally do not spend much time looking for comets, because time on modern research telescopes is typically considered too valuable to spend on projects that are as uncertain as comet seeking.
Or watch the international space station
You keep pushing the idea of wasting my personal time, when I have little due to subpar health, looking at stupid small objects as they which past.
Or phases of Venus.
Whatever.
Observe sunspots
Those are the things that your eye gets by looking too much at the sun. As for the path of the sun and moon, "rises in the east and sets in the west isn't totally accurate. The sun sets in the northwest.
Lunar eclipses are pretty cool. Solar eclipses are overhyped, and screw up the whole day. Bah humbug. I like the soft cool glow of a bright red moon. Which I can look directly at without burning my retine. The stars are not blocked, they are dimmed out by excess light. Light pollution is major nuisance to stargazing. And it is because of light pollution and our damned hhwy dept that I now only can see about five or seven stars in the sky brightly.
These " astronomers" went in with their assumptions, and told themselves the same bullcrap over and over. And it is so threatening to them that anyone should disagree with them, or heaven forbid, simply not care, that they move heaven and easrth to hunt such people down.
Again, anime seems to be a far better use of my time than accepting heathen myths about a godless cosmology.