"Teenagers from Outer Space" released 1959

Teenagers from Outer Space (or perhaps Attack of the Giant Lobster Silhouette) was inflicted upon US theaters June 3, 1959.  It is considered to be one of the "Z-grade" sci-fi films from the 1950s. 

Written and directed by Tom Graeff, the story follows a young alien played by David Love as a part of a scouting invasion searching for food sources for their giant lobster overlords.  He falls in love with a teenage Earth girl and they work together to prevent his cohorts from carrying out their evil plans.

When Teenagers from Outer Space was released, it was met with negative, but not scathing, reviews.  The silhouette of the giant lobster was described as the least-convincing special effect of the 1950s, but other reviews said "flashes of astonishing sensitivity" "actually quite touching" "the show finds its own humble level of dramatic integrity". 

It was riffed by Joel and the bots on Mystery Science Theater 3000 in June 1992. 

Phobos 2, Russian probe, enters orbit around Phobos, discovers UFO, alien base and monolith!

Phobos 2, the Soviet probe launched in July 1988, entered orbit around Phobos, Martian moon, January 29, 1989.  It studied the Martian atmosphere and took 37 pictures of Phobos.  In March 1989, contact with the probe was lost, and the official explanation was an on-board computer malfunction.

However, an investigation of some of the pictures show that Phobos 2 might have been destroyed by a UFO after the Soviet probe took pics of the alien base, their monolith, their flying saucer and its shadow.