In my interest in establishing some dates for the ALIEN universe movies, I decided to do a little more in-depth research at anything that hinted to a date or year in which certain films may have taken place.
PROMETHEUS was the only ALIEN movie that established a solid date: starting in 2189, then the arrival at LV-423 on Dec. 21st, 2093, and ending just after the New Year in 2094.
I don't think this is spoilerific, unless you haven't seen the other ALIEN movies, so I think it's safe to discuss here...but, if you have NOT seen the ALIEN quadrilogy (quindrilogy now, with PROMETHEUS?) , and don't want it spoiled...read....no....further... You have been warned.
Ok....the crux of the PROMETHEUS story (after its "way back in history" beginning) starts in 2089, and finishes? just after the New Year of 2094. It is being put about that this story takes place approximately 30 years before ALIEN. (I'm actually watching ALIEN right now, to confirm a certain something that's always had me curious....and I feel I'm gonna get lost in it all because I am watching the blu-ray version with audio commentary and the Weyland Yutani Datastream running...the latter is similar to the text commentaries made by the Okuda's for the Star Trek DVDs.) Anyhoo....when Dallas is working with MU-TH-UR (MOTHER) for the first time in the story, and he asks: "What' s the story, Mother?"....we see "Interface 2037". I had always wondered if that was the year in which ALIEN took place...2037...but obviously, it's not. Now something else had popped up in the blu-ray menus....the number 2120. This actually would work more to the timeline, especially in keeping with PROMETHEUS taking place some 30+ years before ALIEN. I know there are some made up bios on the crew of the Nostromo in the extra features...but I cannot recall if they actually list any dates.
But, take this a step further...ALIENS is the only other movie out of the ALIEN universe that gives a date (at least, for a past occurrence), when Ripley says: "I just checked the Colony log. Direcive dated 6-12-79, signed Burke, Carter J." Now, if ALIENS (as it had been mentioned in the ALIENS ADVENTURE GAME) takes place in the 22nd century, then that would make it the year 2179... Ripley was in hypersleep for 57 years....2179 is indeed 59 years after the final events of ALIEN, assuming that 2120 is the correct year. The two extra years could've come from the short time of Ripley's return and reassimilation back to Earth, and the travel time taken when she goes with the Colonial Marines back to LV426. Or, it could actually put the year of the USCM's doomed mission around 2181...considering that I do believe the Sulaco inhabitants were in hypersleep for 18 months...if I remember the novelization correctly.
Ok...now, Rebecca "Newt" Jordan was supposedly in the second grade on Acheron/LV-426 at the Hadley's Hope Colony. That would make her character probably about 8 years old. By the time of ALIEN 3, she was estimated to be 12 years old at the time of her death. So, that means about 4 years travel time when Ripley, Hicks, Bishop, and Newt were headed back to Earth in the Sulaco...and had their doomed escape afterward to land on Fiorina (Fury) 161 in ALIEN 3....which, if my years are solid, means that ALIEN 3 takes place in 2185.
ALIEN RESURRECTION takes place some 200 years after Ripley's demise in ALIEN 3. If we took it solidly at 200 years, that would make the year of the events in that movie at 2385...so, the 24th century.
I'm not saying these are solid numbers....I am only basing them around the few solid or semi-solid numbers/dates given in a couple of the movies. Your actual temporal mileage may vary.