dornilteikezraifau lujvo

f1 = r1 = x1 (event; perhaps: spacetime coordinates) is a solstice of extreme r3 = x2 ("ka" construct or season; default: "ka zmadu", which means "Summer solstice", unless context makes this interpretation untenable) at location/of or for celestial body/object d3 = x3 with respect to orbit/sun x4.

x3 is akin to donri2, but is more relevant to the concept of a solstice and the orbital mechanics which may be involved. Use "dunraisa" etc. for some amount of neutrality and objectivity concerning location and any biases which may be at play therefor. For a clever calque of English "soltstice", see: "solsta". See also: "dornilteikeznulfau", "3 = x3 with respect to orbit/sun x4.">ctenilteikezraifau".

In notes:

ctenilteikeznulfau
f1 = r1 = x1 (event; perhaps: spacetime coordinates) is an equinox for season x2 at location/of or for celestial body/object d3 = x3 with respect to orbit/sun x4.
ctenilteikezraifau
f1 = r1 = x1 (event; perhaps: spacetime coordinates) is a solstice of extreme r3 = x2 ("ka" construct or season; default: "ka zmadu", which means "Winter solstice", unless context makes this interpretation untenable) at location/of or for celestial body/object d3 = x3 with respect to orbit/sun x4.
dornilteikeznulfau
f1 = r1 = x1 (event; perhaps: spacetime coordinates) is an equinox for season x2 at location/of or for celestial body/object d3 = x3 with respect to orbit/sun x4.
dornilteikezraifaufa'a
x1 is the temporal direction of/toward solstice x2 (event or spacetime coordinates or season (usually specify year); default: Summer solstice) from origin/in reference frame x3 at location/for body x4 and with respect to orbit/sun x5.