Back in the 1990es
No less than half a dozen science-fiction societies were active in Bucharest in 1997. It has been said (and I agree) that the competition was vital to their evolution. Here's a couple of words on each one I know of. Most of the information below comes from Cristina Săvescu and Traian Bădulescu.
Founded on June 9, 1992, the Planetar has sustained a rich activity, many of his members becoming reputable SF writers of the young generation, of which Traian Bădulescu, Viktor Toroş, Eduard Pandele, Bogdan Bucheru, Anca Amuzescu are only a few. It also attracted older writers like Felix Moga and Ovidiu Petcu.
After hosting the "Picnic..." together in November 1997, Planetar and the Star Trek Club kept coming closer to each other, until the latter was finally engulfed, sometimes during 1998. Members of the two clubs also worked together on the NewsLetter SF, which was distributed to most science-fiction societies in the country.
(I know little about that part. At the time, I wasn't attending the Planetar's meetings.)
The Planetar science-fiction society operated at the "Amiral V. Urseanu" astronomical observatory until after the death of Dr. Harald Alexandrescu on July 16, 2005.
On October 6, 1989, a group of students from UPB (The Polytechnical University of Bucharest) have formed a society for scientific anticipation and science-fiction literature, under the guidance of Ms. Mihaela Muraru-Mândrea. The name String comes from the notorious string theory, that fascinated its founding members.
As the first SF society of the 1990es, String had major contributions to the structuring of this movement in Bucharest; they organized the XXth edition of the ROMCON convention and founded the CSPSF (Center for prospective science and science-fiction), both in the autumn of 1990. String also edited one of the longest-lasting Romanian fanzines.
Reborn in 1995 on the initiative of Mr. Mihai Grămescu, Solaris had a rather special position among the other SF clubs in Bucharest, for it used to bring some of their members together in a neutral environment: Traian Bădulescu and Anca Amuzescu from Planetar, Bogdan Bucheru from String, Chris Chimoiu from Star Trek and Cătălin Stefan -- Rătăcitorii (see below). Other notable Solaris members were Ona Frantz and the veteran Cristina Radulian (who was in the first Solaris, between 1983 and 1987).
Solaris has long ceased to function; a few of its former members have joined the Planetar for a while.
As they introduced themselves on the occasion of the first "Picnic..." in 1997, AlthernaTerra was the first Internet-based science fiction club in Romania. Their web site, founded with the club, was one of the first net-zines dedicated to Romanian sci-fi.
The rest of the... clubs
Other science-fiction clubs used to operate in Bucharest during that time: Rătăcitorii ("The Wanderers") had an inconstant activity sometime between 1995 and 1997, while the CSPSF managed to keep together String, Star Trek and number of non-SF clubs until 1998.