It is the year 2038, and the Earth is slowly being consumed by a space-borne monstrosity dubbed the Black Tide, which is using nanotechnology to remake the planet into something hideously alien.

Erin Olsen works for Project Harmonics, humanity's last-ditch effort to find a new world before the Tide can wipe them out. But when that world is found, and it turns out to be occupied, Erin will need to find the courage to face the unknown in order to save the inhabitants of both worlds.

(Many thanks to Easteu for the fantastic cover image for this story!)

Now with its own TV Tropes page

There is now a follow-up to this story: Sunflower - Side Projects
Sequel: Project Sunflower: Harmony

An earth pony from the classical era once described life as a series of unexpected surprises. For some that’s more true than others. Luminescence knows this all too well. Falling in love with someone outside her species was never part of the plan. But love didn’t much care for her plans.

Likewise Hiro Blueforest only expected to do his graduate studies at the Lunar Institute for Advanced Thaumaturgical Studies. Maybe research for a year or two and then return back to his people’s lands. Now his plans have been derailed and he finds himself stuck in between two cultures and pulled both ways by politics.

It’s not going to be easy for either of them, but the more difficult the problem, the greater the reward!