If you lived on a moon of Jupiter, how would the variable gravity affect you?
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ETpro (
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November 6th, 2013
One of Jupiter’s moons, ice covered Europa, might actually harbor primitive life. Even if there is no life there, there’s water, so building a colony there might be feasible. Europa is slightly smaller than Earth’s moon. If Europa were isolated from Jupiter, you would weigh 13.4% as much on its surface as you weigh here on Earth. But its orbit is close that the gas giant, Jupiter. Within our solar system, Jupiter is second only to the Sun in mass. If Jupiter had a surface to stand on, there you would weigh 2.53 times as much as you do on Earth. In fact, Jupiter’s massive tidal pull on Europa is why there appears to be liquid water under its frozen surface. The forces of nearby Jupiter’s gravity as Europa spins generate enough internal heat to keep much of its water liquid.
So clearly, those gravitational forces would affect a person standing on the moon’s surface. It you stood directly opposite the planet, Jupiter’s gravity would be added to Europa’s, making you heavier than the 13.4% Europa’s own gravitational pull would exert on you. Move to the side closest to the planet, and Jupiter’s gravity would be pulling you up and away from Europa, making you lighter than you were when located opposite the planet. In addition, the tidal pulls of Io and Ganymede, also relatively large moons, would constantly vary as this graphic illustrates. What do you think such a variance of gravitational pulls would do to humans accustomed to the relatively constant gravity of Earth?
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19 Answers
I would be nauseous and have space sickness.
I drink quite a bit so I often feel those effects right here on planet Earth. Living on Europa wouldn’t be that much of a stretch.
As far as modern humans evolving on Europa I think the most profound effect would be on our skeletal structure.
I don’t think that these astro-scientists really “know” much of anything for certain, and get to conveniently change many of their “scientific facts” as necessary. We all grew up being told that Pluto was a planet…..then suddenly, it wasn’t…..now it IS again.
They can tell us anything they want. How could we disprove it if tomorrow’s paper said:
“Using the Hubble telescope, NASA scientists today reported that 30 billion light-years ago, there were likely functioning Studebaker production plants on 14 (or possibly 15) of the 27 moons of Uranus.”
Then we’re all expected to think, “DAMN, those people are smart…..better send them some more money…”
People in orbit are in free fall. No gravity. Einstein use this as an example of relativity. They have only the gravity of the moon they are on to contend with. Constant gravity.
I was a physics major for four years.
It would make me sick to my stomach. One minute I’d be puking on my shoes, the next minute I’d be puking on your shoes.
@talljasperman & @kritiper Glad I brought it up, then. In this low gravity, shame on me if I can’t jump high enough to save my shoes getting spattered. :-)
@Blondesjon Ha! A day for sick humor. I think I’ll go get a drink and think about that.
@OneBadApple Riiiight. Hunches and political speeches are full of truth, but the calculations it takes to keep GPS satellites in geosynchronous orbit so that they can wrok are just a bunch of hooey and you don’t believe those satellites are even there. GPS is a well-known hoax that just seems to work because they filmed in in the Arizona desert. :-)
@Vincentt That’s an outstanding link. Thanks. I wonder if they would take up this question If I sent it in to them.
@gary4books I hear what you’re saying, and follow the logic of it. Indeed you are in free-fall when in orbit, but you are in orbit because you feel the gravity of the object you are orbiting. But I don’t think that answers this question. The tidal forces from Jupiter’s enormous gravity tug on different parts of Europa to different degrees, giving it an egg-like shape instead of being spherical. Europa’s axis is slightly misaligned with Jupiter’s equator plane, and therefore, as it revolves about its axis, the moon’s shape moves. Its ice, seas and even rocky iron core undergo tidal stretching and that’s what generates the heat that allows for liquid oceans. That suggests to me that while I’d feel Europa’s gravity more than Jupiter’s due to my proximity to the moon when standing on its surface, I’d feel a combined tug from Jupiter and Europa on the far side from Jupiter and a just the opposite when on the Jupiter side.
@ETpro Don’t misunderstand, I am not unimpressed with all of the great scientific advances which we all can touch and see every day. But when some egghead scientist tells us that 1.5 million years ago there were definitely four-mile deep lakes containing traces of red sulfur, liquid nitrogen and argon gas on a planet with a circumference of 37,850 kilometers which is 2,750 light-years from Earth, my only response is…...
“Tell your story walkin’, pal…”
@OneBadApple When have you heard that sort of a claim made about a planet that distant?
Scientists publicly proclaim things in language like that all the time. I think they should reach a final conclusion about something simple like Pluto or no Pluto before publishing their “findings” about stars a million miles beyond our galaxy.
I live not far from the Space Coast, and you’d be surprised at how many minutely-planned rocket launches explode without even leaving the pad. How smart can these guys be ?
@OneBadApple Pluto getting demoted to a minor planet isn’t an example of what’s wrong with science, it’s an example of how it works. You can read the story of why Pluto got demoted here, but the important take-away is that science is all about constantly striving to get more accurate and repeatable observations. In the course of doing that, you’re always going to be throwing out old data that was the best available explanation when your observational instruments were more crude. Frankly, those who refuse to change when better information worry me a great deal more than those who are willing to admit they were wrong and accept new and improved findings.
@ETpro Point taken. But as a taxpayer, when Lockheed Martin does some calculations in English and others in metric and their Mars Probe flies right on by the planet, I want my money back.
Space exploration can be a grand and wonderful thing.
Accountability is even more wonderful…
@OneBadApple I can follow that. Equating a for-profit government contractor with a scientist is comparing apples and oranges, though. Surely any sort of apple should know better than that. :-)
Oh, sorry, in my previous resonse, I failed give post the link to Pluto’s demotion to dwarf planet. It’s about 1/6th the mass of Earth’s moon, and we don’t call the Moon a planet, so we shouldn’t view Pluto as one either. Back when we were observing the solar system with primitive telescopes, it was one of 9 objects orbiting the sun and visible to man. That’s how it originally got recorded as a planet.
To me, it all comes under the heading of very costly space science. With all of the great accomplishments, there will always be dubious results, scientific and political BS explanations, and a somewhat proud but always confused American public.
Scientific progress is littered with failures. If we had all the answers, we would not have to explore. The greater the complexity, the more checks and balances are needed. That costs more. In the Mars Climate Orbiter case, their budget was cut so much they did not have the manpower to check every little thing, and one person did not notice that one variable was in English units.
http://en.wikipedia.org/wiki/Mars_Climate_Orbiter
OK then…..respectfully understood.
Now when do I get my money back…??
Not much, I think. The damage to the body, in particular bones and muscles must be compensated similar to what the ISS crew is doing.
I forgot to mention one thing. Did you take the centrifugal forces of Europa orbiting Jupiter into account?
@mattbrowne I didn’t calculate any of it. I asked the question hoping some kind soul here would do that for me. :-)
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