Re: East vs. West - is the galaxy map upside down?

Alec Turner

Alec Turner
Re: East vs. West - is the galaxy map upside down?

So I took a trip out to the Veil nebula. I didn't know this until I got there but there are two, Veil East and Veil West. However, in the orientation that ED presents the galaxy map to us the East nebula is to the left of the West nebula. I was curious, is there an accepted orientation of the galaxy that's used by astronmers and is this different to the default presentation given to us in ED or is there some other perverse reason why the East and West Veil nebulae are the "wrong" way around?
 

marx

marx
As far as I know, these parts of the Veil nebula were named after how their relative positions look from our viewpoint on Earth. Take a look at them from Sol. (No need to fly there, just center the galaxy map on the system.)

Also, the newest Hubble pictures are from 2015. Sept.: see here.
 
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Jackie Silver

Jackie Silver
As Marx says, I believe it's from their appearance from Earth; we rotate at an angle to the galactic plane and it's also going to depend which hemisphere on Earth you're looking from. Makes my head hurt thinking about it. :)

It's quite interesting to see how the different star catalogues map onto the galaxy - the BD catalogue were taken from the northern hemisphere and roughly correspond to the "west and south" side of the galaxy, while the CD and CPD catalogues were taken from the southern hemisphere (ish) and roughly correspond to "east" and "north".
 

Boogyman

B
I don't have time to go hunting for a source link at the moment since lunch time is just about over, but i seem to recall reading that Earth's north-south axis is inverted relative to the galactic axis.
 

Macklin_Fox

Macklin_Fox
A quick image showing galactic latitude and longitude used in astronomy. Galactic lat and long use the Sun as the center. North means the north star is "above" you. East is the direction shown by the angle in green from 0 degrees longitude (toward the center of the galaxy). It's called the right-hand-rule. Using your right hand, point you index from the sun to the center of the galaxy with your thumb pointed up (north). Curl your index finger to your palm, that direction is positive east. For some reason, ED changed the y and z axis, so the ED coordinate system is left-handed.

Galactic Coords.jpg
 
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Sapyx

Sapyx
Look for Polaris - Earth's north pole star in 2017 - and you'll find it at co-ordinates -322, +195, -212 or roughly in the direction of South-West-and-Up. Many things in the sky given "compass-point" names were given them from this reference frame; the galaxy's North Pole, for example, is named that because it is the galactic pole that is closest to Earth's north pole.

"East" and "West" are inverted because the Earth's north pole points generally away from the centre of the galaxy, more out towards the galactic rim. So in that sense, the people of 20th century Earth were viewing the galaxy from the "wrong way around", in the sense that they were "facing the wrong way" when they pointed North.

The Veil Nebulae are in the constellation of Cygnus, which is (roughly) also in the same direction relative to Earth. So it shares the same "backwards orientation" (from the Galactic point of view) as Polaris.
 
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