by Chris Peterson » Sat Sep 14, 2013 1:49 pm
DavidLeodis wrote:I'm not very good at picturing the change in view between the northern and southern hemispheres so I wonder how the occultation would have looked when seen from the Equator. Which way would Venus seem to move relative to the Moon? I'm :?
Occultations always move the same way, and they look the same from either hemisphere. The Moon moves eastward with respect to the background stars (and planets)... no matter which hemisphere you are in. The Moon has a north, south, east, and west limb, and they look the same no matter which hemisphere you are in. It is common to be facing south when viewing or photographing the Moon in the northern hemisphere, and north when doing so from the southern hemisphere. But there are common exceptions to that, especially when the Moon is near a horizon.
This is why terms like "left", "right", "above", and "below" are usually very poor choices when viewing astronomical images without referents for these relative concepts.
Regardless of which hemisphere you are in, an occultation when the Moon is near the eastern horizon will appear to reappear "above" the Moon. Near the western horizon, it will reappear "below" the Moon. For higher events, it will reappear "right" of the Moon if you are facing south, and "left" of the Moon if you are facing north. Instead of imagining how it might look while
standing in a different hemisphere, imagine it from the perspective of
lying on the ground, with your head in the same direction regardless of hemisphere.
[quote="DavidLeodis"]I'm not very good at picturing the change in view between the northern and southern hemispheres so I wonder how the occultation would have looked when seen from the Equator. Which way would Venus seem to move relative to the Moon? I'm :?[/quote]
Occultations always move the same way, and they look the same from either hemisphere. The Moon moves eastward with respect to the background stars (and planets)... no matter which hemisphere you are in. The Moon has a north, south, east, and west limb, and they look the same no matter which hemisphere you are in. It is common to be facing south when viewing or photographing the Moon in the northern hemisphere, and north when doing so from the southern hemisphere. But there are common exceptions to that, especially when the Moon is near a horizon.
This is why terms like "left", "right", "above", and "below" are usually very poor choices when viewing astronomical images without referents for these relative concepts.
Regardless of which hemisphere you are in, an occultation when the Moon is near the eastern horizon will appear to reappear "above" the Moon. Near the western horizon, it will reappear "below" the Moon. For higher events, it will reappear "right" of the Moon if you are facing south, and "left" of the Moon if you are facing north. Instead of imagining how it might look while [i]standing [/i]in a different hemisphere, imagine it from the perspective of [i]lying on the ground[/i], with your head in the same direction regardless of hemisphere.