Remember when you were a kid and you were taught that Pluto was a planet? There were nine planets, according to your fifth-grade teacher, and Pluto was the adorable one on the end. Your teacher even taught you a festive mnemonic device so you’d never forget the planets and which order they were in: My Very Educated Mother Just Served Us Nine Pizzas. Pizzas, you were told, stood for Pluto.

But Pluto got demoted sometime after you graduated from high school, and now you know what My Very Educated Mother Just Served Us? Nothing. Pluto is no longer a planet, and Neptune, I’m pretty sure, stands for Neglect.

In the years since Pluto’s demise, my brain has come to know that Pluto isn’t technically a planet anymore (it’s a dwarf planet, which sounds cool but is actually far less cool than being a regular planet). My heart, however, hasn’t accepted it yet. Frankly, I don’t think I’ll be able to truly embrace the concept until Neil deGrasse Tyson shows up at my condo and explains it to me in person. I will insist we hold hands while he goes over the visual aids (to help me through this difficult time), and then we will have a dance party in fallen Pluto’s honor. But until that happens, I’ll know the facts—but I won’t really know the facts.

In the exact same way that I “know” Pluto is no longer a planet, I “know” that Matt and I are leaving for our four-month travel extravaganza in less than five weeks. It makes tons of sense in my head, but my heart just isn’t convinced that it’s true.

My brain knows that we will go dogsledding on a glacier this summer, towed by a prancing pack of Icelandic huskies, but my brain is certain we’ll just lead my geriatric dog around the neighborhood and scoop her poop out of mulch beds. My head is very busy booking accommodations in Berlin and researching public transportation options, filling out spreadsheets and creating daily budgets, but my heart keeps wondering when the next season of Game of Thrones will start and whether or not Matt and I should host a watch party. (Should we serve Dothraki blood pies?)

Part of what is so surreal to me is the knowledge that, while we’re leaving in July, we won’t be back until a week before Thanksgiving. We will leave on some humid, 90-degree day and ride the light rail to the airport in tiny shorts (Matt) and sweaty t-shirts (me), and we’ll return in the middle of November, shivering despite our sensible travel layers and wishing desperately we had brought parkas with us to the French Riviera. It’s a tangible reminder that the world will, quite literally, keep turning while we’re gone and that the world we leave will not be the world we return to. Is that why this doesn’t feel real yet? (More importantly, is this what time travel is like?)

For the record, purchasing Eurail tickets and international airline tickets didn’t make the trip feel any more real. Neither did filling out LOA paperwork with my HR partner at work, blowing a ridiculous amount of cash on wrinkle- and smell-resistant clothing, or telling our wedding caterer not to send us our one-year anniversary cake this September because “we’ll be in Vienna.” Frankly, the only thing that makes me come close to feeling like we’re going is that we’ll have to say goodbye to our dog.

Obviously, we can’t bring her with us, but the fact of the matter is that she’s an old girl—she’s going to live with my folks while we’re gone, but she might not still be around when we get back. Yes, she’s doing really well for her age, but she’s a 15-year-old Doberman—so there’s no way to know whether this will be truly goodbye or simply see you at Thanksgiving. It  could be either, truly, and there’s no unknowing that fact in either brain or heart. I know it, and I know it, and in that way, I’m glad I don’t really feel like we’re leaving. We’re buddies, and I rather like feeling as though she, Matt, and I have infinite time together.

But, regardless of how I feel, or what I know, or what I don’t know, we’re going. It’s a fact. Whether or not it feels real to me, my husband and I will be sitting on a plane bound for Reykjavik in five short weeks, eating cheese in Paris in seven, and going everywhere else right after that. My guess is that it’ll start to feel real somewhere around the security screen at MSP Airport and that somewhere around my third glass of overpriced, airport-terminal wine, my brain and heart will reconcile, and I’ll both know and know.

I could be wrong, of course. Maybe it will only feel real when we’re trying to speak Croatian or trying to figure out the exchange rate from dollars to zlotys in Krakow. Or maybe only when we get back, or maybe not even then. Maybe we’ll come home and the whole thing will still feel like a good dream that happened to someone else. Maybe we’ll grow old and floppy like our dog and still never believe it was real.

But “the good thing about [it] is,” says my buddy Neil —though the “it” for him is science and not travel plans, but we’re about to come full-circle so shut your face—, “it’s true whether or not you believe in it.”

Then again, he also said, “Next time you’re stunned by large Moon on horizon, bend over and view it between your legs. The effect goes away entirely.”

So, you know, we’ll see.

Follow the esteemed Mr. Tyson on Twitter: @neiltyson

Photo by C m handler (Own work) [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons