Dear [first name],

I’d like to tell you a story about a rock. A very large rock – an ultradense asteroid, as a matter of fact. When it passes a hair’s width from the lush planet where our story takes place, (which is where? Earth or somewhere else?) its massive gravity completely upends the planet’s ecology, spreading environmental mayhem that leaves the hunter-gatherer tribes just beginning to appear in disarray. What follows in my novel, The Second Transit, is the story of this rock’s return to the planet every 2,276 years of its orbit, in 90,000 words that capture the women, men and civilizations its passage impacts. [While this is a very creative way to introduce your novel, I wouldn’t recommend doing it. Just stick to the book’s details. THE SECOND TRANSIT is a 90,000 (insert category and genre)]. 

After one passage, a group of survivors from the wreckage of their riverside village discover an early city where the agricultural revolution is beginning to take hold. In another, a medieval kingdom is threatened by starving, invading hordes. Later, we meet a little girl whose grandfather is the first to realize that their people’s apocalyptic religious mythology might not be completely fictional; and who realizes, as a grown woman, that she must find a way to preserve the truth about their world, and perhaps even warn future generations thousands of years into the future. In each era of the great asteroid’s passage, slaves, scholars, office workers and explorers of space encounter crises of faith and of life and death as they draw closer to a confrontation with their planet’s recurring curse. (Okay, for each of these times the asteroid passes, you should introduce us to the main character of that story. I’m curious how you present each timeline…do you weave them out of order and present their stories simultaneously or do you present it chronologically? Do the timelines connect at all? Remember, your query needs to have a hook, the main plot, and stakes. Consider this with your characters because I don’t know any of them from reading this query so I can’t connect with anyone.) 

In The Second Transit, historical fiction meets science/speculative fiction which eschews a “privileged” character perspective in lieu of the common people of every age. It explores how inexorable environmental changes buffet and change the people and cultures that are built around them, and how fragile those cultures truly are. It also touches on the difficulty its characters have to grasp a disaster whose effective timescale vastly outstrips any one individual’s lifespan. In this way, the book can be read as an allegory for climate change. (It’s not a good idea to explain the novel to the agent/editor after you’ve pitched it. Your pitch should do the job for you.) 

I would be thrilled to share the full manuscript for your review. Thank you very much for your time and consideration.

Cheers,
I think I get the premise of your novel and it’s great, you just need to flush out the query a bit more. Revise and resubmit if you are interested.