I’m currently doing a project for school where I have to make constellation observations. The map that was provided by my teacher had mixed up west and east – at least, I thought they did. On a regular compass rose it’s north, east, south, then west, right? But I googled other maps and most turned out with west and east “switched.” Can someone clarify why this is? And will this affect how I should observe/record the constellations?
+Because it is probably the same concept as a planisphere. If you hold a planisphere over your head (with north pointing to the north), when you look up, it not only represents the sky you are seeing, but the directions are also pointing correctly.
Actually, there exists a bit of confusion.
In the sky, the direction called “West” is, for an observer in the northern hemisphere, to the right when looking south.
After the Sun passes south, it continues towards the right, towards West.
So, if the observer draws a constellation as he sees it (from a location in the northern hemisphere), north will be up and south will be down. West is to the RIGHT.
When a star (or planet) is to the right of the Sun or Moon, it is said to be west.
First object of confusion (this one is only a confusion of understanding):
When Venus is at its greatest Western elongation from the Sun (to the right of the Sun for a northern observer), we actually see it in the East in the morning. Being west of the Sun, it is rising before the Sun (we see it before sunrise) and it sets before the Sun (we cannot see it at or after sunset).
Of course, when its elongation is East, we see it in the Western sky after sunset.
The bigger confusion came first with the Moon, then with planets.
When making the first maps of the Moon, the edge of the visible disk that was towards the observer’s west was called “west”. A feature on the Moon’s face that was to the right was said to be west.
However, once people had been on the Moon, the maps had to be made as if it were possible to be on the Moon. Therefore, the direction towards the right had to be called east.
This led to the strange situation where a crater well east of the central meridian was described as being on the west limb.
To avoid this confusion, we now talk of the “leading” side (the side that sets first) and the trailing side.
But there are still cases of maps using the older standard.
Yes, it does cause confusion.
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In general:
Star maps (showing the sky as seen from Earth) still show West to be to the right of North.
Surface maps of the Moon and of planets show East to the right of North.
It is because you are looking up at the stars, not down at the ground. If you lay on the ground face down with your head to the north, your right hand will be to the east. If you were face up, your right hand would be to the west.
just hold up your map, match north. then all other things will be matched.
Well, it all boils down to what they used to call the “music of the spheres”. A typical map of the Earth is an observation of the surface from above the surface, from the outside, with North UP, South DOWN, East to your right hand, and West to your left hand. Now, imagine looking at that map from the backside, as if you were INSIDE the Earth looking OUT at the surface from below. Note that North is still UP, and South is DOWN, but East is now toward your left hand and West toward your right hand. See? The East/West is reversed because of your position inside the sphere. The olden days ancestors imagined the sky to be a celestial sphere and we were on the inside looking out, with the Earth at the center of everything, surrounded by crystal spheres on which the heavens moved. So, the celestial sphere is exactly like that Earth map from inside the Earth, only now we are talking the celestial sphere. Likewise, East and West are going to be reversed exactly like that imaginary map from inside the Earth. It is all very logical if you think of the celestial spheres which were promoted by the church as the way the universe works. Today, we know, of course, there are NO spheres, but still the map of the heavens, the constellations, has stayed the same because there is NO reason to change it. It works to navigate as well today as it did when no one knew any different. Remember, for all intents and purposes, you are looking at the inside of a sphere and it will NOT affect any observations you or anyone else makes.