Across the Universe: Giving and Receiving (Where Credit Is Due)

This column first ran in The Tablet in February 2017

A paper just posted online by two Caltech astronomers describes observations at an 8-meter telescope of more than 300 faint TNOs (Trans-Neptunian Objects), small lumps of ice orbiting out beyond Neptune. These are leftover chunks of the materials that went into the planets, witnesses to the events that formed our solar system. The shapes of their orbits tells us how the large planets near them have pulled on their paths over time; patterns in the evolution of their surfaces hint at events in our solar system over the last four billion years.

Steve, Bill, and I were once trying to take images of the centaur Pholus (see the box) and this dreadful galaxy almost got in the way. Image is made of several images taken in different colors, hence the odd colors of the moving object, Pholus

Nearly twenty years ago I started working on just such observations with Steve Tegler (Northern Arizona University) and Bill Romanishin (University of Oklahoma). Back then, Steve and Bill had first noticed that the first handful of TNOs they’d observed didn’t show a range of colors but rather fell into two distinct color classes, red and gray. Looking for a telescope where they could continue their survey, they asked to use our 2-meter Vatican Advanced Technology Telescope. I operated the telescope, while chiming in on their all-night speculations as to what it all meant.

We found that the red/gray split in the colors didn’t apply to objects in more well-behaved circular orbits; those were just red. Methane ice turns red when it is exposed to the sun’s ultraviolet light; perhaps all TNOs were once reddened this way, but maybe the ones with disturbed orbits experienced impacts that churned up fresh, colorless ice to their surfaces. But when we observed these bodies as they spun, we never found any that were red on one side and gray on the other, the way you might expect of an old red surface hit by a recent impact. And careful measurements in infrared light showed that the gray surfaces, rather than being fresh ice, were actually much darker than the red surfaces… more black than gray.

Even after observing for twenty years, we only have data on about 150 such objects – each object essentially represents one night of observations. Meanwhile, other astronomers observing these bodies haven’t seen as clear a trend as we have. It’s become a minor controversy. Now this new paper triples the number of bodies observed, and measures objects much fainter, much smaller, than our telescope could see. The new results? Like us, they see that TNOs with disturbed orbits come in two distinct colors, red and gray.

It’s a delight to have our observations validated… except, reading this new paper, I find no reference to any of the papers that we’ve published on the topic over the last 20 years. It cites other papers in the controversy; but not ours. Probably the authors were just sloppy. Still, I am miffed.

But should I be? It’s not as if Steve, Bill, or I need the credit to build up our careers. I am already an observatory director, Steve is a department chair, and Bill is now retired. Shouldn’t the validation of our science, the truth itself, be enough?

It isn’t.

Science is a “gift economy;” your status is earned not by how much you accumulate, but by how much you give. References to your papers is one way the value of your gift is recognized, one of the few rewards you get for your hard work. It keeps the community of science alive.

Science is not the data; it’s the community who ponder the data. Like all human communities — think of the Church — we can never forget that our labour relies on the labour of others around us. Like our data, we too need validation.