Anyone use these as some sort of factor in their adventures. Call of Cthulhu uses it of course. But sometimes it feels only in the most rudimentary fashion.

Things like comets and eclipses that happen on more or less specific time tables. Planetary alignments? Other phenomena?

Dragon way back had a mini-module murder mystery and one of the clues was that the murdered wizard was studying planetary alignments and patterns.

Dragonlance had the 3 magic user factions all waxing and waning as their respective moons did and an eclipse of one two or all three had an effect on them as well.

In my own book every 1000 years the planets align. Which causes various surges in the fundamental elements of the world. Usually imbuing life to something that was inanimate before. Usually of some sort of elemental type. But sometimes causing animals or even items to become animate or even more-or-less sentient. The effect starts and ends during the period the moon is also aligned. 10 days. And hits its peak on the last day when a comet with a 50 year cycle falls into the conjunction as well. Anyone conceived or born on that day has a much higher chance to express magic or psi aptitude.

Another one is that during any lunar eclipse people can petition Death to have one individual raised. But if their reason is not a good one. They die too. For obvious reasons lots of pets come back to life during these events. And the Chromatic/Rainbow Comet. Which can only be seen from certain random locations and angles. Seeing it is viewed as a sign of good fortune. And the Phantom Comet which only undead or those who have been at the threshold of death can see.

Lots of interesting ways to incorporate astronomical events into a campaign.

We chucked the Dragonlance moon cycle thing into the garbage. It was a cool part of the lore and even fun to deal with on the Gold Box games, but it was just too annoying for us.

I haven't done a lot with planets aligning, but years ago we used to have these bundles of cheap paper with writing on them that you could spend hours reading through delivered for cheap to your house everyday. I ran a campaign where I used horoscopes as a supplement to random encounter tables to generate events, hooks, or even mess with saving throws.

It's inbuilt into the system of Artesia, which is one hell of an overlooked gem.