On 4 January 2015, due to a supposed planetary alignment, Jupiter and Pluto are apparently going to overwhelm Earth’s surface gravity and so allow us to float like the astronauts on the space station.
It is, of course, total bollocks, not least because the idea began life as an April Fools day joke in 1976, and the exact same hoax did the rounds this time last year. But I’m fascinated by the fact that such an idea can gain traction in the first place.
The sole bodies in the solar system that have human-perceptible effect on Earth are the Moon and the Sun, which cause tides. Even if Jupiter’s effect on us was more than the 0.000037% of Earth surface gravity that it actually is, the only way it could cause us to perceive gravity as ‘nullified’ would be if Earth was somehow a fixed object, nailed down to something else that Jupiter wasn’t pulling on. In other words, if we humans were affected and the Earth wasn’t. As matters stand, the Earth is pulled along with us by other astronomical bodies.
As for the ‘alignment’, Pluto has a mass 0.002 times that of the Earth, or thereabouts (more soon, when New Horizons checks it out). Jupiter’s mass is 317 times that of Earth. Even if they were the same distance from us, Jupiter’s pull is so huge by comparison that Pluto can be discounted. But wait, it’s worse. In December 2014, Pluto was 5.03 billion kilometres from Earth. Jupiter was 739 million kilometres. Gravitational pull operates according to the inverse square law, meaning that if distance doubles, pull drops by a power of two; so even if they were pulling together, which they’re not, Pluto’s pull is so insignificant I won’t even bother doing the math.
And don’t get me started about what ‘zero gravity’ means, versus ‘free fall’, which is what actually gives the impression of ‘floating’ in space.
But hey, who am I to argue the point? We all know that in reality the only way to avert disaster is if you send me all your money. Now. In unmarked bills…
Copyright © Matthew Wright 2015