3 ms·

Nice. I wonder if the daytime brightness would really be that impressive? I guess they have a lot higher albedo than the moon, but the moon is barely visible d

by lutorm 17y ago

Nice. I wonder if the daytime brightness would really be that impressive? I guess they have a lot higher albedo than the moon, but the moon is barely visible during the day. Also, they wouldn't be visible all night most of the time, because they'd be shaded by the Earth. But at night they would probably be bright enough that it would be difficult to see stars. A lot brighter than the full moon, for sure. The lack of stars may even have prevented the development of astronomy, and for sure it would be a big headache for astronomers! Maybe having observatories exactly on the equator would work, but otherwise it would be very difficult to see anything faint due to the glare.

electromagnetic 17y ago
As far as I know our comprehension of brightness is logarithmic. Something with a ten-fold increase in brightness over the moon, would in reality look barely any brighter. I wouldn't doubt that if the earth had a series of rings that we would still be able to see the stars. However, this would obviously depend on the composition of the rings and their albedo. Also it would vary by latitude, at the equator the rings would be barely visible. Latitude would have likely been easily discernible far sooner than the usage of astronomy in navigation, it wouldn't be hard to measure the width of the rings to measure your latitude. Even a crude measurement would have been immensely useful to early ships crews. Longitude would likely have been more problematic, however knowing the moons phases and the time of day (which would be discernible by the position of Earth's shadow on the rings) would likely be enough to determine longitude. I doubt human development would have been greatly affected by having planetary rings, it may even have helped the technological revolution by enabling long-distance sailing earlier.
- lutorm 17y ago
  It's true that the eye response is logarithmic to overall brightness, but that does not mean that you see something faint next to something bright nearly as easily if you make the bright thing ten times brighter. The number of stars you can see at full moon is already very limited now. I'd guess that the limiting magnitude goes from 6 to 3. I'm not sure it would have made a big difference for latitude determination. It's already readily available by measuring the noon height of the sun. About using the moon, have you read the book "Longitude"? It's a really interesting book about the quest to measure longitude. To measure it, you essentially need a clock that is independent of local time. I doubt the rings would help there. While in principle you could use the phases of the moon, you need the time to an accuracy of at least tens of minutes to be useful, and that seems very difficult to accomplish with the Moon.

by lutorm 17y ago

electromagnetic 17y ago

As far as I know our comprehension of brightness is logarithmic. Something with a ten-fold increase in brightness over the moon, would in reality look barely any brighter. I wouldn't doubt that if the earth had a series of rings that we would still be able to see the stars. However, this would obviously depend on the composition of the rings and their albedo. Also it would vary by latitude, at the equator the rings would be barely visible. Latitude would have likely been easily discernible far sooner than the usage of astronomy in navigation, it wouldn't be hard to measure the width of the rings to measure your latitude. Even a crude measurement would have been immensely useful to early ships crews. Longitude would likely have been more problematic, however knowing the moons phases and the time of day (which would be discernible by the position of Earth's shadow on the rings) would likely be enough to determine longitude. I doubt human development would have been greatly affected by having planetary rings, it may even have helped the technological revolution by enabling long-distance sailing earlier.

lutorm 17y ago
It's true that the eye response is logarithmic to overall brightness, but that does not mean that you see something faint next to something bright nearly as easily if you make the bright thing ten times brighter. The number of stars you can see at full moon is already very limited now. I'd guess that the limiting magnitude goes from 6 to 3. I'm not sure it would have made a big difference for latitude determination. It's already readily available by measuring the noon height of the sun. About using the moon, have you read the book "Longitude"? It's a really interesting book about the quest to measure longitude. To measure it, you essentially need a clock that is independent of local time. I doubt the rings would help there. While in principle you could use the phases of the moon, you need the time to an accuracy of at least tens of minutes to be useful, and that seems very difficult to accomplish with the Moon.