"Zero hour" refers to the termination of a countdown, the moment of a spaceship's launch.
When NASA gets ready to launch a rocket or spaceship, they use such military-based lingo as "T minus 30 minutes" to count down to the time of launch. The "T" stands for "termination," as in the termination of the countdown (and the moment of launch). The "termination" is zero hour.
Drug reference, anyone?
Though this song is pretty much set in its astronaut narrative, the phrase "high as a kite" is a common idiom almost always used to refer to drug use. There's nothing to suggest that lyricist Bernie Taupin really intended the double entendre, but given that the song came out at the peak of the stoner '70s, what else are we supposed to think? Interestingly, space songs often involved some metaphorical interpretation of drug use. "Space Oddity" a song written by David Bowie, is considered to be a drug song by some, who see the influence of drug-altered consciousness in its lines, "This is Major Tom to ground control/ I'm stepping through the door/ And I'm floating in a most peculiar way/ And the stars look very different today." At the same time, being "high" in both songs could just mean being really really high—literally—in the atmosphere. It's also important to remember that American Neil Armstrong became the first man to walk on the moon in 1969, a mere three years before Elton John sang "Rocket Man." Space exploration was on everyone's mind.
Bernie Taupin's inspiration for the song came from the Ray Bradbury short story "The Rocket Man," which can be found in a collection of short stories called The Illustrated Man.
Ray Bradbury is a highly influential and celebrated science fiction writer, the author of Fahrenheit 451 and other sci fi classics. His short story, "The Rocket Man," tells the tale of a conflicted astronaut who, during his three-month long voyages in space, yearns for home. And once he's home, he yearns for space. At one point in the story, he warns his son, "Don't ever be a Rocket Man," because of the effect of his career on his family. The Rocket Man himself, though, seems more or less accepting of his fate. Taupin's lyrics capture this conflicted character—the line "I'm a rocket man" is both triumphant and defeated in tone. Space is both "lonely" and "timeless."
That's a scientific fact. Mars is extremely cold, regularly experiencing average temperatures rarely if ever seen even in the coldest places on Earth.
The average temperature on Mars usually hovers around -55 Celsius (or -67 Fahrenheit, if you prefer). Martian summers can heat up to a balmy -5 C (-23 F), while winters can dip as low as -107 C (-161 F). The coldest that it has ever been on Earth is -128.6 F, in Antarctica. So if you ever go to Mars, make sure to bring a nice jacket.
Well, maybe. We don't know for sure whether there is life on Mars.
Scientists have long wondered about life on Mars. Starting centuries ago, astronomers have speculated that because Mars has ice caps, and seasons like Earth does, it may have (or may have once had) life on it. The earliest scientists even suspected that the dark recesses on Mars were oceans or lakes. Once we understood that those were actually barren canyons, we assumed that life was simply not an option on Mars. In the late '70s, the Viking Landers traveled to Mars and carried out experiments to detect life. Originally labeled as "inconclusive," the positive result of one of the four experiments carried out on that mission has since been proven to be a false positive. On the bright side for alien enthusiasts, the planet does contain water, perhaps even in liquid form, under its ice caps. While the bacteria aliens who could conceivably inhabit this area might not be suited to raising human space children, it's still life! Cross your fingers!
NASA must have seriously slacked off on its hiring standards if our rocket man is allowed to become an astronaut without understanding the science behind it.
In reality, American astronauts are required to have at least a bachelor's degree in engineering, biological science, mathematics, or physics. An advanced degree is desirable. Other requirements include 1,000 hours of experience piloting a jet aircraft, 20 months in an intensive training program, and passing a rigorous physical exam. Becoming an astronaut is not easy. But songwriter Taupin is painting the astronaut in this song as an everyman. He's more relatable, perhaps, if he's just workin' that 9 to 5 like everyone else in the world.