Timeline for Why doesn't Earth appear smudgy or blurred in space photographs due to its fast rotation?
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| Feb 24, 2017 at 15:42 | history | edited | user139580 | CC BY-SA 3.0 |
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| Feb 23, 2017 at 15:04 | comment | added | Mukul Kumar | It could be possible because of relative motion...as the camera also could be geostationary | |
| Feb 22, 2017 at 22:46 | comment | added | Glenn Slayden | Intuitive answer: because the planet is so big, you have to be far away from it to take the picture with a typical (i.e.) 50mm lens. If, from that vantage, you then used a long lens to zoom in to any appreciable degree, the planet would indeed appear to be moving quite fast. More so as your zoomed view nears the equator; if you zoom-in to view a pole, you probably won't see much (relative) motion :-) | |
| Feb 22, 2017 at 18:42 | answer | added | teldon james turner | timeline score: 1 | |
| Feb 22, 2017 at 14:52 | comment | added | uhoh | @Christian the linked XKCD what-if is indeed required reading, as is the Bad Astronomy linked within. | |
| Feb 22, 2017 at 14:04 | comment | added | user139580 | @luk32 That is very obvious. Although rotation speed is/can measured in rad/s, it can be converted into linear speed. Nevertheless, thanks for your comment. :-) I just wanted to keep the question simple and straightforward without any jargon. | |
| Feb 22, 2017 at 13:57 | comment | added | luk32 | The question has fundamental flaw. Rotation speed is not measured in [m/s]. That should be the 1st clue, that this way of thinking is very wrong. | |
| Feb 22, 2017 at 13:11 | comment | added | Christian | Mandatory XKCD What-If: what-if.xkcd.com/32 | |
| Feb 22, 2017 at 4:25 | comment | added | user139580 | @FilipHaglund Done ! | |
| Feb 22, 2017 at 4:24 | history | edited | user139580 | CC BY-SA 3.0 |
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| S Feb 22, 2017 at 3:26 | history | edited | Maxim Umansky | CC BY-SA 3.0 |
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| S Feb 22, 2017 at 3:26 | history | suggested | RandomDSdevel | CC BY-SA 3.0 |
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| Feb 22, 2017 at 2:15 | review | Suggested edits | |||
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| Feb 21, 2017 at 19:10 | comment | added | Drathier | Commas are used for decimal points in many countries, so many people (including me) read a value a thousand times smaller than intended. Could someone with enough rep remove the comma? | |
| Feb 21, 2017 at 16:04 | vote | accept | CommunityBot | ||
| Feb 21, 2017 at 9:16 | comment | added | PlasmaHH | Think about why a ball that you rotate once every 24 hours can be photographed pretty sharp. | |
| Feb 21, 2017 at 9:03 | history | edited | user139580 | CC BY-SA 3.0 |
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| Feb 21, 2017 at 0:35 | comment | added | Errol Hunt | Fascinating discussion. But... wouldn't the velocity of the satellite (and thus the camera) be the most important factor, rather than the velocity of the Earth's surface? The Earth's surface moves at maximum (equator) ~1600 kph. But any satellite close enough to be usefully taking pics (say, 200-500km up) would be doing upwards of 25,000 kph*. Camera movement would be 20x Earth's surface movement (still not enough to cause blurring, as per TFB's calcs). *Orbital velocity = sqrt [(G M)/R] | |
| Feb 20, 2017 at 19:41 | comment | added | Dawood ibn Kareem | Same reason you can take a good photo of the moon, while standing on a planet that's rotating at around 1675 km/h. | |
| Feb 20, 2017 at 19:03 | history | edited | Qmechanic♦ | CC BY-SA 3.0 |
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| Feb 20, 2017 at 19:00 | history | protected | Qmechanic♦ | ||
| Feb 20, 2017 at 18:39 | answer | added | macgyver_sc | timeline score: 20 | |
| Feb 20, 2017 at 18:33 | comment | added | jamesqf | Most of the answers (though correct) seem to be neglecting the obvious: the Earth is pretty bright, so you can use a short exposure - 1/1000 second or less, perhaps. Same as you do shooting fast-moving objects on Earth. | |
| Feb 20, 2017 at 17:14 | answer | added | Brian Moths | timeline score: 7 | |
| Feb 20, 2017 at 16:27 | comment | added | Luaan | You underestimate how large the Earth is. You get 0.5 km/s rotation on the equator, while the whole of the Earth is 12.000 km - you would have to have the Earth 40k pixels wide to notice a difference in even one pixel with a 1 second exposure, even if the camera weren't orbiting the Earth. In contrast, reconaissance satellites (which need to make a much more detailed photo) do make rather blurry pictures, despite doing all their best to prevent that (e.g. rotating the camera in the oposite direction to minimise the velocity difference). | |
| Feb 20, 2017 at 16:14 | history | tweeted | twitter.com/StackPhysics/status/833711318045753345 | ||
| Feb 20, 2017 at 14:25 | answer | added | user107153 | timeline score: 73 | |
| Feb 20, 2017 at 13:39 | history | edited | Diracology |
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| Feb 20, 2017 at 13:37 | answer | added | Diracology | timeline score: 35 | |
| Feb 20, 2017 at 13:37 | comment | added | Steeven | How many pixels on the camera do you pass by when you run in front of the camera 1 meter away as compared to 100 meters away? Remember that the frame becomes bigger with distance | |
| Feb 20, 2017 at 13:32 | comment | added | jaromrax | There is also a movement of a spacecraft around the Earth. Spacecraft is launched in the sense of the Earth rotation, so forget about Earth rotation and ask about the spacecraft velocity. + Normal airplane has 900 km/h, which is not far from your number anyway, why there is no blur? | |
| Feb 20, 2017 at 13:24 | history | edited | user139580 | CC BY-SA 3.0 |
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| Feb 20, 2017 at 13:18 | history | asked | user139580 | CC BY-SA 3.0 |