Really basic, when the sun falls and darkness takes over, creature spawn and aggression is increase. Awww'h, I can see the horde of toxic zombie monkeys now.
Yay, more things to rip off from Terraria! Because that's what we need! More things senselessly copy/pasted from a previous game!
Oh how I want this, currently night feels well not like night... In my opinion the peaceful creatures on the planet would not appear (as if they were hiding) and normal angry monsters would aggro all the time and run at you in hoards.
..but is it really that senseless? Anyways, I looked at the update Tensey posted and I like. Although more hostility would be better, for example a planet once a Apex colony is ravished by a zombify disease. Kinda like the movie "I am Legend" the zombies come from hiding and hunt in the night. Creates a base defense type feeling, but the enemies don't have to be zombies, it could be a tribe of Floran who've been tracking you. Perhaps random attacks during the night, would make some paranoid.
We don't need zombies. I can totally understand special nocturnal creatures, but we don't need to have every uninhabited planet suddenly and for no discernible reason become a zombie siege when the sun goes down. That's stupid. Mobs spawned at night in Minecraft and Terraria to force people to build structures to defend themselves. In Starbound, as soon as zombies show up you can just pop up back to your ship. There's no threat. It's a terrible, senseless idea that's only being suggested because other games of the genre has it.
night time has a set of mobs that don't spawn during the day lingering mobs from the day time will get an increase in stats even though it should only be the night set that gets a boost they seem to be like the day time set 1 species that is passive and everything else aggressive the mobs at night are stronger already what more did u want? xD
Frankly, all the constantly spawning slimes and zombies did in Terraria was annoy me while building until I had the weapons to one-shot them without even thinking, then they were trivial. I'm glad you can have a moment's peace in Starbound without monsters constantly ambling towards you.
One of the best features about Starbound are the endless types of planets. I believe it would be fun to have the option of finding a hostile planet where its inhabitants begin their attack under the cover of darkness. Those Floran tribes need to eat man. *Perhaps I should have posted this in the environment/planets suggestion thread.
Riddick will save us! Anyways, planets with more numerous or more hostile enemies wouldn't be a bad thing, darkness or daylight. As long as there are regular and peaceful planets at the other end of the spectrum. Terraria's constant trickle of enemies was just an annoyance.
I like the latter idea, about having higher leveled planets generate with unique enemy AI, becoming progressively more violent and invasive until you reach, as you mentioned, planets with hordes that attack at night. Would be a far more interesting choice to build a home, because of the possibility of having a constant food source. You could build intricate defenses and farms to collect the goodies, or build a cabin and survive like we all did back in Terraria.