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In 2001:A Space Odyssey, from Space Station V the Earth appears to be spinning around a center that is near the edge of the planet. Phone call from space station scene

If the same station (300 meters in diameter) was in a geostationary orbit (35,786 km from the Earth), would the apparent center of spin of the Earth appear to be at the center of the planet, or slightly off center of the planet's center to the human eye? Using Earth's diameter as 12,750 km.

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    $\begingroup$ Looking at that clip, the speed of the rotation makes me think that it's more the station's rotation than the planet's rotation $\endgroup$
    – Andon
    Commented Oct 15, 2019 at 18:12
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    $\begingroup$ The answer is in the question. Geo-stationary: the earth will appear stationary from the perspective of the station. $\endgroup$
    – workerjoe
    Commented Oct 15, 2019 at 18:28
  • $\begingroup$ If an astronaut was floating freely at a geostationary orbit and spun around with the axis of their rotation pointing to the Earth, wouldn't the Earth appear to spin in the opposite direction of their rotation? $\endgroup$
    – Bob516
    Commented Oct 15, 2019 at 18:32
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    $\begingroup$ Yes the rest of the universe will appear as the earth would be spinning around you and the earth presenting the same face to you exactly as the moon does. $\endgroup$ Commented Oct 15, 2019 at 20:40
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    $\begingroup$ It depends entirely on how the observer's axis of rotation is oriented relative to the Earth. It need no be pointing at the Earth at all. $\endgroup$ Commented Oct 15, 2019 at 21:08

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From geostationary orbit, by definition, the Earth will always present the same face. The terminators (sunrise and sunset lines) will creep across the surface, but the portion of the Earth that is visible (nearly 50% of the surface, cloud cover and lighting permitting) will not change (assuming the slight oversimplification of an orbital position that doesn't need frequent adjustment due to perturbation).

Any rotation you might see would be, as it likely was in that 2001 clip, due to the movement of the spacecraft or station you're viewing the Earth from. The apparent center of rotation will always be along the station's axis; if that points through the Earth at all, it will do it twice each orbit, and the Earth will appear to rotate around that axis (as the sun and moon appear to turn around the Earth's axis from the surface) and also move fore and aft (taking the axes to be forward and rearward) over multiple rotations (since the station's rotation is much less than an hour).

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The rotation you're describing is impossible.

A planet rotates around its center of mass. The only way for this to occur is if its center of mass were to lie outside of the body. This can't happen, unless somehow the edge of the planet was significantly denser (and thus more massive) than the rest of the planet. But if the mass of the planet is high enough to make the planet spherical, denser materials always sink towards the center and lighter materials towards the surface.

Ignoring if this was possible and just accepting it as an occurrence, then in a geostationary orbit:

The planet would appear to be stationary to the space station. No rotation at all would be observable.

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  • $\begingroup$ I was asking about the Earth appearing to rotate, as in the video clip from the movie, not actually rotating. Would saying the Earth is spinning around a point that is near its edge of the planet be more acceptable? $\endgroup$
    – Bob516
    Commented Oct 15, 2019 at 18:26
  • $\begingroup$ "the Earth is spinning around a point that is near its edge of the planet" is the way I interpreted the question from the very beginning. $\endgroup$
    – overlord
    Commented Oct 15, 2019 at 18:31
  • $\begingroup$ Is the video clip showing the Earth spinning around not accurate? $\endgroup$
    – Bob516
    Commented Oct 15, 2019 at 18:35
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    $\begingroup$ @Bob516 As others have stated, it is more likely that the station itself is rotating, which could cause the phenomenon from the video. $\endgroup$
    – overlord
    Commented Oct 15, 2019 at 18:49
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    $\begingroup$ @Bob516 That would depend on a lot of things. The orbit of the station and the rotation of the station are independent of one another. But if the view of the space station is centered on the Earth, the Earth would visibly appear to be spinning in place about its center. $\endgroup$
    – overlord
    Commented Oct 15, 2019 at 19:08

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