Timeline for What is the largest possible appearance of a celestial body in the sky?
Current License: CC BY-SA 4.0
27 events
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| Apr 5 at 19:58 | comment | added | Ben C | Do comet tails count? Perhaps not because the tail is material being lost from the comet, and so it is not a single solid body and not stable. But some amazing historical comet tails exceeded 90 degrees of arc! | |
| Apr 12, 2021 at 5:44 | vote | accept | fgysin | ||
| Apr 12, 2021 at 3:15 | comment | added | M. A. Golding | @fgysin reinstate Monica. Part three of my aswer to: worldbuilding.stackexchange.com/questions/200498/… Discusses another type of astronomical situation were two astronomical objects can have very large angular diameters in each other's skies. Possibly the largest angular diameters which are possible. | |
| Mar 31, 2021 at 14:31 | comment | added | fgysin | @ZeissIkon You presume correctly. | |
| Mar 31, 2021 at 14:30 | comment | added | Zeiss Ikon | I presume by your wording that you won't accept deep sky objects like nebulae or galaxies? | |
| Mar 31, 2021 at 14:28 | history | edited | fgysin | CC BY-SA 4.0 |
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| Mar 30, 2021 at 22:35 | comment | added | reirab | I'm assuming that we can't cheat and simply place the observer on the celestial body? For example, Earth is a celestial body. I can stand in a deep, narrow valley and have Earth occupy more than 180 degrees of my field of view. :) | |
| Mar 30, 2021 at 21:07 | history | became hot network question | |||
| Mar 30, 2021 at 21:00 | answer | added | M. A. Golding | timeline score: 3 | |
| Mar 30, 2021 at 19:04 | answer | added | Starfish Prime | timeline score: 11 | |
| Mar 30, 2021 at 18:15 | answer | added | L. IJspeert | timeline score: 15 | |
| Mar 30, 2021 at 17:18 | comment | added | John Dallman | If someone wants to do the arithmetic, put Saturn in Earth's orbit, and Earth in orbit around Saturn. Use the rigid-satellite Roche Limit formula to find out how close Earth can be to Saturn. Work out the angular diameter from that. | |
| Mar 30, 2021 at 15:11 | history | edited | fgysin | CC BY-SA 4.0 |
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| Mar 30, 2021 at 14:59 | comment | added | Frostfyre | @AlexP Also accounting for the Roche limit, since OP wants the system to be stable. Figuring out the math is beyond my expertise, though. | |
| Mar 30, 2021 at 14:45 | comment | added | AlexP | @Triodixane: In practice the problem should be approached from the other end. First set an angular size as a goal; then compute how large the object subtending that angle should be at various distances; finally figure out what it can be. For example: eventually the Sun will puff up into a red giant. How large will it be in Earth's sky? Or imagine the Moon 8 times as large as it really is (twice the diameter) and orbiting at 20,000 km instead of 400,000 km; this is conceivable. Won't it appear about 50 times as large as it does now, covering a whopping 15 degrees in the sky? | |
| Mar 30, 2021 at 14:26 | history | edited | fgysin | CC BY-SA 4.0 |
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| Mar 30, 2021 at 14:18 | comment | added | fgysin | @AlexP I thought this was obvious, but apparently it wasn't... I'm interested in celestial bodies e.g. stars/planets/moons/... Also given my assumptions above 180° is obviously impossible, since at that time you would be squashed flat between the two touching surfaces... That is neither a stable arrangement, nor survivable. | |
| Mar 30, 2021 at 14:16 | history | edited | fgysin | CC BY-SA 4.0 |
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| Mar 30, 2021 at 14:14 | comment | added | Frostfyre | Simplest answer: standing at the point of impact between one planet in a stable orbit around a star and a rogue planet; the rogue planet will take up the entire field of view. | |
| Mar 30, 2021 at 14:13 | comment | added | Trioxidane | @AlexP can you double check on that? Seems to me you're describing a Celestial object, not a Celestial body. As well it seems to be an answer, not a comment. | |
| Mar 30, 2021 at 13:51 | comment | added | Starfish Prime | Do you definitely mean "planet" by the current official definition, or are you including moons and things as well? Do you have any restrictions on "binary planet", like mass ratios or where the barycenter should be, etc? | |
| Mar 30, 2021 at 12:05 | comment | added | AlexP | Very obviously, the maximum angular size of a celestial body in arc seconds is 180 degrees times 60 minutes times 60 seconds equals 648,000 arc seconds. For example, the Milky Way in Earth's night sky extends from horizon to horizon. See a great panoramic picture. | |
| Mar 30, 2021 at 12:01 | history | edited | fgysin | CC BY-SA 4.0 |
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| Mar 30, 2021 at 11:57 | comment | added | fgysin | I'm asking about realistic and stable celestial body constellations. I'll update the question accordingly. | |
| Mar 30, 2021 at 11:43 | comment | added | dubious | Are you asking what the visual limit of a sphere in your field of view is, or do you want the gravity and orbits to also be realistic? | |
| Mar 30, 2021 at 11:08 | history | notice added | L.Dutch♦ | Hard Science | |
| Mar 30, 2021 at 11:01 | history | asked | fgysin | CC BY-SA 4.0 |