Background: The Rise and Fall of Ziggy Stardust and the Spiders from Mars (often shortened to Ziggy Stardust) is the fifth studio album by English musician David Bowie, released on 16 June 1972 in the United Kingdom. It was produced by Bowie and Ken Scott and features contributions from the Spiders from Mars, Bowie's backing band - Mick Ronson, Trevor Bolder and Mick Woodmansey. The album was recorded in Trident Studios, London, like his previous album, Hunky Dory. Most of the album was recorded in November 1971 with further sessions in January and early February 1972.
Context: The Rise and Fall of Ziggy Stardust and The Spiders from Mars is about a bisexual alien rock superstar, called Ziggy Stardust. Ziggy Stardust was not conceived as a concept album and much of the story was written after the album was recorded. The characters were androgynous. Mick "Woody" Woodmansey, drummer for the Spiders from Mars, said the clothes they had worn had "femininity and sheer outrageousness", and that the characters' looks "definitely appealed to our rebellious artistic instincts". Nenad Georgievski of All About Jazz said the record was presented with "high-heeled boots, multicolored dresses, extravagant makeup and outrageous sexuality". Bowie had already developed an androgynous appearance, which was approved by critics, but received mixed reactions from audiences. His love of acting led his total immersion in the characters he created for his music. After acting the same role over an extended period, it became impossible for him to separate Ziggy Stardust (and subsequently The Thin White Duke) from his own offstage character. Bowie said that Ziggy "wouldn't leave me alone for years. That was when it all started to go sour ... My whole personality was affected. It became very dangerous. I really did have doubts about my sanity."  The character was inspired by British rock 'n' roll singer Vince Taylor, whom David Bowie met after Taylor had had a breakdown and believed himself to be a cross between a god and an alien. However, Taylor was only part of the blueprint for the character. Other influences included the cult musician Legendary Stardust Cowboy and Kansai Yamamoto, who designed the costumes Bowie wore during the tour. An alternative theory is that, during a tour, Bowie developed the concept of Ziggy as a melding of the persona of Iggy Pop with the music of Lou Reed, producing "the ultimate pop idol". A girlfriend recalled his "scrawling notes on a cocktail napkin about a crazy rock star named Iggy or Ziggy", and on his return to England he declared his intention to create a character "who looks like he's landed from Mars".  The Ziggy Stardust name came partly from the Legendary Stardust Cowboy, and partly because Ziggy was "one of the few Christian names I could find beginning with the letter 'Z'". In 1990, Bowie explained that the "Ziggy" part came from a tailor's shop called Ziggy's that he passed on a train. He liked it because it had "that Iggy [Pop] connotation but it was a tailor's shop, and I thought, Well, this whole thing is gonna be about clothes, so it was my own little joke calling him Ziggy. So Ziggy Stardust was a real compilation of things."  In the album's plotline, humanity will end within five years, because of lack of natural resources. Ziggy Stardust starts to believe in the existence of "infinites", extraterrestrial beings who are black hole jumpers, and in a spaceman who will be coming down to save the Earth. According to Bowie, he "takes himself up to the incredible spiritual heights and is kept alive by his disciples". During the song "Rock 'n' Roll Suicide", the infinites arrive, and tear Ziggy Stardust to pieces on stage, taking his elements to become visible.
Question: Most popular theme?

Answer:
extraterrestrial beings who are black hole jumpers, and in a spaceman who will be coming down to save the Earth.