Of Particular Significance

Floating in Space … But Why?

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 07/08/2013

Have you perhaps wanted to go into space someday, so you could float around and do somersaults like the astronauts you see on TV? You know, out in space, where everything floats, because … because

because there’s no gravity in outer space???

  • Hmm… If there were no gravity in space, what would keep the Earth orbiting the Sun? Or the Moon orbiting the Earth?

umm… because…

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11 Responses

  1. Nice article as usual. I will try this on curious laymen!! Sometime I have used centrifugal force (a bad word) balancing gravitation in rotating frame. Apart from the fact that purists may hate it, it does not work in a free fall straight down. Thanks.

  2. Another proof that gravity is still there: the Apollo spacecraft where going at escape velocity (~24,000 MPH) when leaving earth but over time slowed down to ~2,000 MPH by Earth’s gravity. Then lunar gravity dominated and they accelerated again.

    I remember in grade school seeing an animation of a cannon on a mountain that was very much like Matt’s figure 5. The animation was a great way to explain orbits to a ten year old…

  3. (Please note that the link to the article is invisible in some browsers – you may want to change the color of the hyperlinked text.)

  4. Great job as usual. It might be worth mentioning at “End of discussion” that all objects regardless of composition (the coins are metal and the book is paper) as well as no matter how heavy fall in exactly the same way.

  5. God drew lines in spacetime called geodesics. When astronauts seek out these specially marked lines, where they can truly be at rest, instead tirelessly accelerating all the time like we do here on the surface of the planet. It is exhausting.

    1. But ‘microgravity’ itself is a term for ‘when there is little gravity’ which suggests that gravity is absent. (To be more specific G-forces are nearly zero.) This just adds to the confusion.

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[UPDATE May 10, 4:00 pm Boston Time, 10:00 pm EU time: AURORAS MAY BE ACTIVE NOW!] I don’t use exclamation marks in blog post titles

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 05/10/2024

A couple of days ago, I noted a chance of auroras (a.k.a. northern and southern lights) this week. That chance just went up again, with

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 05/09/2024