Add Geocentric Solar Ecliptic (GSE) frame

🎯 Goal

Produce plots like this:

And this:

https://twitter.com/planet4589/status/910720207701897221

💡 Possible solutions

Perhaps it’s similar to this one, or even exactly this one! http://docs.astropy.org/en/stable/api/astropy.coordinates.GeocentricTrueEcliptic.html

📋 Steps to solve the problem

• Comment below about what you’ve started working on.
• Add, commit, push your changes
• Submit a pull request and add this in comments - Addresses #<put issue number here>
• Ask for a review in comments section of pull request
• Celebrate your contribution to this project 🎉

[astrojuanlu]

Check out https://github.com/poliastro/poliastro/blob/master/src/poliastro/frames.py

[shreyasbapat]

2.1 Geocentric solar ecliptic (GSE) This system has its X axis towards the Sun and its Z axis perpendicular to the plane of the Earth’s orbit around the Sun (positive North). This system is fixed with respect to the Earth-Sun line. It is convenient for specifying magnetospheric boundaries. It has also been widely adopted as the system for representing vector quantities in space physics databases.

While, GeocentricTrueEcliptic says:

Geocentric ecliptic coordinates. These origin of the coordinates are the geocenter (Earth), with the x axis pointing to the true (not mean) equinox at the time specified by the equinox attribute, and the xy-plane in the plane of the ecliptic for that date.

I don’t think that’s the same 😕