A collection of basic rules for space. All are probably House Rules, but either necessary to fill in gaps (such as semaphore code for communication between ships) or because of gaps and oversights in the rule set.
This message was last updated by the GM at 19:14, Mon 17 Oct 2022.

OK, I just checked, and the book specifically states that even a planet's atmosphere extends outward the same distance as the planet diameter.

That would be 8000 miles for Earth, or about 11 days to get out of it. Someone at WoTC didn't do the math.

Even using real world distances (60 miles) that's 20 hours fro the slowest ships and almost 8 for the fastest. A lot for one helmsman, and changing helmsman would be....risky, what with the period you'd be falling and all.

I've used the size categories from the previous edition, and Earth's actual atmosphere size as a guideline to come up with atmosphere envelopes for planets:
Size A: not planets. less than 10 miles across envelope is quite large, gravity plane is flat
Size B:  10-100 miles across, 15 miles
Size C:  100-1k miles across, 30 miles
Size D:  1k-4k miles across, 45 miles
Size E:  4k-10k miles across, 60 miles (Earth)
Size F:  10k-40k miles across, 75 miles
Size G:  100k-1000k miles across, 90 miles (Jupiter, all atmosphere in reality)

There may well be exceptions, of course: a planet that is a ball of water may have very little air around it. And a planet that is all air is going to be thousands of miles of nowhere to land.
This message was last edited by the GM at 22:51, Tue 11 Oct 2022.

Well, another rough patch in the rules.

The rules give 3 basic choices for DMs to choose from, each of which makes for a different combat situation. For a ship your speed (25' a round) it's basically 10 rounds out, 20 rounds out, and 40 rounds out. Note that your own air envelope is about 3 rounds of travel in size, from bow to vacuum

The old system had differing speeds, weapon ranges due to a lack of gravity, and the like, and made for a random roll of 1d20 Hexes. It had speeds starting at 1 hexd per round, and possbly achieving 6 hexes per round. So, I'll use that pattern: 1d20 rounds based on your top encounter speed. The other ship/objects speed is not a concern for this range determination, but it could well approach on it's own, speeding contact/weapon range time.

And, yes, with low rolls, you could come to encounter speed with overlapping envelopes. But then, with two large enough ships, the closer choice from the book could, also.

Each of these may have the skill replaced with Vehicle(Space) to reflect spacer training. DCs will likely be low, most times:

-Swapping orientation passing through a gravity plane would be Dex(Acrobatics) as movement if time is short. Otherwise you're getting up from prone, literally. And that's assuming a floor is handy. Other times a fall has turned into a climb, such as barnacle scrapping duty. DC 5 most times, after some experience at it, DC 10 the first time or two, until you've rolled 3 successes (which may be over multiple instances).

-Boarding in combat is a Strength(Athletics) roll. You're jumping a gap that may be up to 5' per the rules given. See jump notes in another post

-Semaphore codes are universal (except when they aren't, for some reason) in space. They likely won't be the same as water ships use. See Semaphore notes in another post.

-Most sailor jobs (Vehicles(water)) will have an equivalent Spacer job (vehicles(space)), of course, but as other specialty tasks come up, I will add them to this list.

The boarding rules in AA almost follow all the typical jumping rules. Boarding is usually a 5' standing long jump with a DC 10 to clear an obstacle of up to 1.25 feet.

Typically a standing long jump of 5 or less is automatic for a Strength of 10 or more. However for a strength of 8 or 9, which can't clear the gap, more is needed. For a 1' I'll allow a Strength (Athletic) roll.

Of course, both ships have guard rails that need to be cleared. Standing on yours to remove the DC 10 is another Acrobatics check. If boarding is a frequent activity, place crates along your guard rails to stand on. Even then you still need the to hope their guardrail isn't higher (BTW, 3' is typical for a guardrail, you can only clear 16 inches, even with a roll).

So, in an effort to assume AA isn't just poorly playtested, let's assume a trained spacer (one with Vehicle(Spacer) proficiency) can clear a guardrail(only) of 3' or less with a  standing broad jump...if he or she has a strength of 10 or higher. Everyone else needs prior planning and/or a die roll or two.

Semaphore signals in Space are pretty universal, except when they are not, usually due to isolation of one party for the recorded past.

Basically, you can wave signals to other ships and understand replaies unless , for some reason, they are determined not to use the same code patterns.

One of those reasons might be that they are using a planetary system, implying they are new to space.

While Vehicle(space) shares one flag language, Vehicle(water) doesn't. Each planet has their own, and oceans far enough apart not to have contact (Such as Medieval Atlantic and Pacific) might have different flag languages.

Ok, folks, as I was already down the Light in Space rabbit hole, a fact about Ceres light:

It is 11% Earth normal. A Full moon on Earth, by contrast, is .1% daytime normal.

Jupiter gets 4%. That's 40x a full moon.

A full moon MIGHT count as Dim light per the PHB, so I'll set THAT cutoff at 1% Earthlight

Of course, this is direct sunlight. the tiniest shadow sets you in Dark conditions.