Describing location of solar features

[procky1845]

Hello,

Quick question, what is the correct terminology for describing the location of solar features.

For example do the terms preceding and following have any meaning with the Sun? Or East and West? Or something else?

Thanks,

Lee

[xtreemchaos]

from rotation i go upper or lower oncoming limb, upper or lower center and upper or lower off going limb with the word near used a bit, it works everybody seams to know what im on about but you can go by the compass its your pref

[Merlin66]

If you orientate the solar image with north to the top, it will match the images on Gong and SpaceWeatherLive (other than an E-W horizontal flip when using a diagonal), then "appearing in the NE", "disappearing in the SW" are unambiguous.

https://www.atoptics.co.uk/tiltsun.htm

The tiltingsun graphics helps a lot.

 

 

[procky1845]

So, I'm now a bit confused.

My understanding for some time has been that the moon and the planets as perceived by a normal unmodified view (i.e. disregarding changes in orientation/flipped images due to telescopes) imagined against a compass would be N at top, E to the right, S at bottom, W to the left, but when just looking at the night sky the celestial E and W are reversed, so N at top, W at the right, S at the bottom, E to the left (and I understand why that is).

I've just been reading a book that suggests that E and W on the Sun are akin to the celestial E and W (so the opposite of the planets and moon).

• Firstly, is this correct?
• Secondly, is it just the Sun that is different to the planets which otherwise follow the first convention (N,E,S,W) or are there further oddities that I am unaware of? i.e. does this differ on a planet by planet basis as well?

Any help appreciated! I thought I understood this but clearly not!

[Merlin66]

The "normal view" of the Sun has North at top, East to the left. The rotation (East to West) of the Sun brings new activity onto the visible disk from the East edge, and they disappear at the West edge.

"Preceding" and "following" is a common terminology to establish E-W on astronomical objects.  When the object drifts across the FOV the drift direction is towards the western edge (ie nearest the western horizon).

https://www.cloudynights.com/topic/629874-cardinal-directions-celestial-vs-lunar-planetary/

 

[procky1845]

Thanks, thats useful.

So would I be correct then in thinking that preceding is always the same direction as celestial west and following is always the same direction as celestial east? 

In other words it has no bearing on which way the planet is rotating, its about direction of travel through the sky. I ask the question as Mars spins one way and Venus spins the other but based on my assumption above preceding for both would be in the same direction i.e. celestial west.

[Merlin66]

8 hours ago, procky1845 said:

So would I be correct then in thinking that preceding is always the same direction as celestial west and following is always the same direction as celestial east? 

Yes, that's correct.