Why do most photos of galaxies/stars say it took X amount of hours to capture? Can a single photo not be taken?
In: Physics
Multiple hours and a single photo are not mutually exclusive concepts.
Galaxies in the sky are very faint so you need to collect light for a long time to get detailed images.
You can expose photographic film or a digital sensor for a long time so even if it took hours to captures is might just be one long exposure in one photo.
Even in normal conditions, the exposure time depends on light levels. You might expose for 1/1500 s in outdoor sunlight but 1/10 is indoor in dim light or multiple second outdoor in the moonlight. Stars and galaxies is just even dimmer and require even longer exposure time.
When you did it with a film that was how it was done but with digital sensors, it is possible to split it up in multiple shorter captures and add them together in software so any animality like a satellite that moves in front of the camera and reflects light back can be ignored.
Latest Answers