Lost in Space (part the 3rd)

Section 3: Perspective

Author’s note: this is the third section in a chapter on how we find our way around. You can read the first section here, and the second section here.

Invisible guidelines are hard to work with, but unfortunately, this isn’t all. As if the Right Ascension and Declination system isn’t complicated enough already, there’s a major limitation of this system - namely, that it appears different to different people in different places and at different times. For me, floating on a boat in Lake Michigan (one can dream…), I might see the Andromeda Galaxy as a fuzzy blip 30 degrees above the horizon in the north east. But you, from the beach in Key Largo might see it as only 13 degrees above the horizon, and your aunt in Hawai’i wouldn’t be able to see it at all until hours later, and then in a different spot on the sky. 

Then again, isn’t this true of ourselves, and they ways we try to view the world? We define objective “ground truth” - an online quiz for determining how liberal or conservative we are, or a set of creeds or doctrines that you can map yourself onto. But in practice it’s way messier than that, isn’t it? 

Ok there are a few problems here. One is that the earth is big: it blocks half the sky from us all the time. So if you’re in Australia and I’m in Chicago we’re going to be looking at different skies,  and if I move around on the planet, my perspective shifts - different stars, different Right Ascensions and Declinations, will be overhead. I see that supposedly universal coordinate system a little differently. 

Even a little shift can make a difference. I remember a time I was scheduled to do some observing with Arecibo Observatory - a giant radio dish 1 kilometer around built into a sink hole in Puerto Rico. I am a heavy sleeper but I’d managed to wake up and get ready without waking my fellow grad student Greg. I think I brushed my teeth to scrub away that sleepy fog - I at least got dressed and was at the door ready to leave, quite proud of myself that I’d been so quiet.  When suddenly the window panes  - great heavy wooden doors made to block out even the noontime sun  for sleeping astronomers - started slamming, the stilted wooden house, not updated from its use in the film Contact shaking, rocking - and Greg sat bolt upright. 

Four seconds later it was over. What was that? Down in the control room, on its concrete slab, the operators on duty had hardly even felt it – a magnitude 6.2 earthquake in the fault line just off the coast. This seemed fine: our data seemed a little off that night - fewer directions than expected, and more waves in the baseline than expected, but nothing too worrisome. The next day we were scheduled for a telescope tour. The main staff don’t work on weekends, but someone was there to take us up the terrifying catwalk out to the hanging instrument platform, 2000 tons of metal suspended 400 feet above the dish below. We had a great tour. Little did we know that come Monday staff would inspect the telescope, and find that one of the cables that holds up the dish had been frayed in the earthquake, unraveling such that the platform had shifted about 6 inches. A small shift. But enough to make our data from that night entirely worthless - we’d been pointing all wrong and didn’t even know it. And of course, one broken cable puts the rest are under far more stress. A small fact. But one that completely changed our view of the telescope platform tour. We could have died! 

Another small fact: this small fray was the beginning of the end for this iconic observatory. Though the cable was repaired 7 years later a hurricane would snap another cable. And the other cables, already weaker from this extra stress would begin to imperceptibly stretch. Just days later, before the snapped cable could be repaired, the whole platform would come down. Amazing the impact of a 6-inch shift.

Since even little shifts matter, this means that I have to be able to convert between what I see now - say that the sun is 65 degrees above the southern horizon - to something I (and everyone) can see from anywhere - the sun is at RA = 90 degrees and Dec +23.5 degrees. 

And it’s not just me moving around. To do astronomy, I have to remember that everyone is in a slightly different place. If I want to tell another astronomer where to point her telescope, I need to do some work to put things in terms we mutually understand, and I need to do some work if I want to see what she’s seeing. And to do astronomy I have to remember it’s a big world out there: for some people the big dipper is never visible, for others it’s always there. For some there are days when the sun never sets. Craziness. And some people, buried in smoggy haze and bright lights, can’t even see the stars (what sadness is this: that the byproduct of our needs often ends up creating disconnect for others; some can’t see so that others can). 

I wonder, how often does my opinion that others are lost or wrong stem from my unwillingness to go over to view things from their perspective?  I read a book in middle school called Walk Two Moons, a story about a supposed lunatic killer that draws its title from the epigraph “Don't judge a man until you've walked two moons in his moccasins.” I find myself coming back to this again and again and again. Like when I find myself driving like my mother, or taking those classic travel photos like my dad. Or my first year teaching. I remembered all those reviews I’d written of my professors, how they should have done this differently or that differently. Turns out teaching is hard! I had a professor who sweated profusely when he taught. How awkward. Turns out, a class with 65 students is a stressful workout.  

Another problem: even if I stay put, the earth is spinning. So while our RA-Dec coordinate system is fixed to the sky - trying to establish a universal truth - we are constantly in motion relative to that system. A star with a fixed RA and Dec will rise in the east and set in the west each day, just like the sun, moon, and everything else. Each second a slightly different RA is directly overhead. So even if I’m communicating in the shared language of our coordinate grid, each minute, each interaction, it shifts a little bit.  

And here’s the thing, just when I think I’ve nailed something down in my life, I realize the world is moving too. And I can’t catch up to it. Taking the size of the earth and the fact that it spins 24 hours in a day lets us calculate how fast you would have to drive on the equator to keep the sun directly overhead. 1038 miles per hour. That’s fast. And I can’t spend my whole life keeping up. Sometimes you just have to land. 

I think about a girl I dated for 2.5 years in college. She was great - we had lots of things in common: similar views on faith, similar connection to music, similar cultural upbringing, and much more. We talked about everything. Clearly, we were in more or less the same place, at least emotionally, and socially. But… we went to different universities, and had different friends. Those 1 hour 17 minute drives seemed not a big deal, like we were making it work. Maybe we’re stronger because of it, right?! But there was something I didn’t anticipate: though we thought we had the drive to make things work, we underestimated the speed with which the world spins, and the speed with which our perspectives shift. During the week our experiences were different - we talked with different people, read different books, took different classes. It’s like trees changing color. You don’t even notice the differences cropping up, and then boom. It’s fall. And at some point, it became too much to correct. Our breakup was difficult, even more so because it was so hard to understand. Correcting for perspective - this is the difficult work of community - the work of our lives. 

For astronomers we have it comparatively easy. We’ve taught computers to do much of the hard work of converting for us, though we still can easily mess it up, and so can they. This is foundational to doing the rest of our astronomy, and you gotta get it right. If you aren’t vigilant, with a properly set up motor to drive your telescope to move with the sky, your target can slip away.