Does the Sun have permanent geographical features?
Equivalent formulations of this question:
- Would it make any sense to draw a map of the Sun?
- Is the Sun heterogeneous with respect to latitude and longitude? (I know that it is heterogeneous with respect to altitude/depth)
I know that the Sun does not rotate uniformly, so any map would line up differently as time passes. However, this does not rule out a slice of the Sun at a given latitude having permanent geographical features, since this slice does rotate uniformly.
Of course, even geographical features on Earth are not really permanent, they change on long time scales. I don't expect the Sun to have any eternal features, I'm really just thinking about features that change on long time scales, or at least longer than a few months (e.g. not sunspots).
This might be relevant: https://www.wired.com/2016/04/man-whos-drawn-sun-almost-every-day-40-years/
Also, how can there be permanent features on a big ball of gas and plasma? It seems similar to asking if there are any permanent features on top of the ocean...
As I understand it the 'surface' spins, would this create any visible phenomena at the poles? Or would the activity from below overpower any structure that might appear?
@RonJohn Jupiter is a big ball of gas and, yet, it has permanent (or at least long-lasting) features.
Might be a nice little 50 meter bump in pressure at both the spin poles, or the magnetic poles. We've got nothing that could show it to us, if it was there.
In about 4 billion years our sun will explode, so no feature is permanent. Until then it is round.
@cybernard -The Sun is Oblate: https://www.noao.edu/noao/noaonews/dec97/node2.html
@cybernard : no, our Sun will not explode, it's not big enough. It will bloat, shed its outer atmosphere and collapse into a degenerate white dwarf, then slowly cool. Nothing at all like a supernova.
@RonJohn there are permanent features of the ocean (maybe not "on top" of the ocean), such as coral reefs, different species in different areas, etc.
As you suspect the Sun does not have any permanent surface features. Up till 1951 the longest actually observed sunspot group lasted 134 days see http://adsabs.harvard.edu/full/1951ASPL....6..146P. That duration gives you an idea how long sunspot groups last. There are associated with coronal holes which would last about as long. However, the structure (shape size) of the group and any coronal hole would be constantly changing.
Temporary maps are made and there is a heliographic co-ordinate system, with a latitude and longitude.
The sunspots show the rotation of the Sun, and so a north and south solar pole can be found. North is in the same side of the ecliptic as the Earth's north pole).
Solar longitude is much more arbitary. The zero helographic meridian is defined as the plane (solar pole to solar pole) passing through where the solar equator crossed the plane of the ecliptic (earths orbital plane) at Greenwich mean noon on January 1, 1854. see http://wso.stanford.edu/words/Coordinates.html
Since then astronomers have just used a constant rotation rate based upon the suns equatorial rotation rate. These are called Carrington Solar Coordinates
A similar system is used for the longitude of the gas giant planets like Jupiter and Saturn.
If you're not limited to the visible spectrum, the Sun has more-or-less permanent coronal holes at its poles which are nearly always present (albeit constantly changing in shape and size). These coronal holes are responsible for generating the "fast" solar wind. These change on fast enough time scales though that its not useful to make a map of them (or other coronal holes which may crop up).
Below is an image of one such coronal hole.
The Sun has a north and south pole, and an equator. These can be considered geographic features.
I wouldn't call equator a "feature". Any spherical-ish object that's spinning about an axis has an equator, and arbitrary other lines of latitude. It's not clear to me if the poles are really features, for the same reason -- the link with the sun's magnetic field, for example, is complex but even the Earth's magnetic field isn't aligned with the poles as defined by the rotational axis.