by Sarah Scoles
Recently in the astronomy world, a press release about exoplanets -- and the news reports that subsequently tumbled out into the world -- committed a faux pas: overstating the conclusion of a scientific paper.
On April 18, the Harvard-Smithsonian Center for Astrophysics issued a press release entitled "Two Water Worlds for the Price of One."
First of all, what price?
Second of all, the actual scientific paper does not ever say the planets are water worlds.
The press release says:
- "Modeling by researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) suggests that both planets are water worlds, their surfaces completely covered by a global ocean with no land in sight."
And the lead author's direct quote in the press release is:
- "'These planets are unlike anything in our solar system. They have endless oceans.'"
Not to be so 2004, but ORLY?
In "Water planets in the habitable zone: Atmospheric chemistry, observable features, and the case of Kepler-62e and -62f," to be published in a future issue of The Astrophysical Journal, the authors are not trying to prove that 62e and 62f are awash in Caribbean beauty (without the beach umbrellas). The paper takes an idea -- that water planets in the habitable zone (HZ) can exist -- and presents a model for how they could exist, how their atmospheres and oceans would interact, and how we could tell from thousands of light-years away that Earth-sized orbs were not dirty deserts but "beautiful blue planets" (Kaltenegger).
Within the paper, the team then tests their model using 62e and 62f. The authors essentially ask, "Hey, what characteristics would these planets need to have hypothetical 'endless oceans'? And by tweaking that list of available characteristics can we actually make our models of these two planets acquire and maintain 'endless oceans'? All within the framework of the assumptions we made about planets that have endless oceans?"
What the paper did not ask is, "Do these planets have endless oceans?" What it did ask was, "Could they, and would we be able to tell?"
The answer the authors come up with is, "Yes, ma'am." 62e and 62f could be water planets. They are "the first viable candidates," given their diameters and their distances from their star.
But paper states, "Other possibilities remain open until their actual masses are measured." And in a Science paper reporting the planets' actual discovery, the authors say, "Theoretical models of Kepler-62e and -62f ... suggest that both planets could be solid, either with a rocky composition or composed of mostly solid water in their bulk" (Borucki, et al., 2013).
It's cool that they're Earthish-sized and in the habitable zone! It's cool that they could work as water planets, if we "assume they are indeed water planets with low-eccentricity orbits" (Kaltenegger, et al., 2013). It's really cool!
But that is not what the CfA's press release said, not what the batted-around, poetical quote says, and not the general character of the news releases based on the press release/conference.
Here's the flavor of the coverage:
Press release: But what if our Sun had not one but two habitable ocean worlds? Astronomers have found such a planetary system orbiting the star Kepler-62.
Space.com: Computer models suggest both planets are covered by uninterrupted oceans.
Huffington Post: While nobody knows what the two exoplanets look like, a separate modeling study suggests they're both probably water worlds covered by endless, uninterrupted global oceans.
Wired.com: Endless oceans cover newly discovered, possibly habitable, planets.
Some articles expressed such certitude about the planets' wetness and then later said, without finding the statements contradictory, that all of this was hypothetical pending more information. Time magazine was reliable and admitted, "Borucki and the other Kepler scientists were quick to say they had no direct evidence that either planet actually has liquid water on its surface."
What to do?
I'm all for presenting scientific results in such a way that people become excited about them. That is, after all, the point of this blog. But science is our very human attempt to find out the truth about the universe. And exaggerating claims, even if it makes some teenager in Freeport, Kansas (pop: 6), run upstairs to her mom and proclaim that science is awesome she wants to become the most successful exoplanet hunter ever when she grows up and her mom decides to donate the $1 billion inheritance she got when her grandfather died to the Kepler space telescope's successor -- even if exaggeration leads to such grand results, it's not the way we should be talking about scientific results.
As surgeon/scientist/blogger Orac said in a post entitled "Misrepresenting Science" on his ScienceBlog, "[Scientists] want to justify the press release. Too many caveats and cautions make our work sound less important (or, more accurately, less certain) to a lay audience, and if it’s one thing that’s hard to explain to a lay audience it’s the inherent uncertainty in science. We can’t avoid that; we have to embrace it and work to explain it to the public."
Better to say, "Look, scientists are figuring out how to tell what other planets are made of. Isn't that cool? Aren't you excited? And these planets? They might not be so different from ours. Someday we'll know more. For now, we found out that they could be covered in water. Regardless of what they're wrapped in, they're a present from Kepler, and we'll take them."
Just as we will take Kepler's next discoveries -- which will surely be of even smaller, even more habitably zoned, even bluer or greener or browner, even BETTER exoplanets.
In the meantime, let's go lasso an asteroid.
L. Kaltenegger, D. Sasselov, & S. Rugheimer (2013). Water Planets in the Habitable Zone: Atmospheric Chemistry, Observable Features, and the case of Kepler-62e and -62f The Astrophysical Journal DOI: arXiv:1304.5058v1
Borucki, W., Agol, E., Fressin, F., Kaltenegger, L., Rowe, J., Isaacson, H., Fischer, D., Batalha, N., Lissauer, J., Marcy, G., Fabrycky, D., Desert, J., Bryson, S., Barclay, T., Bastien, F., Boss, A., Brugamyer, E., Buchhave, L., Burke, C., Caldwell, D., Carter, J., Charbonneau, D., Crepp, J., Christensen-Dalsgaard, J., Christiansen, J., Ciardi, D., Cochran, W., DeVore, E., Doyle, L., Dupree, A., Endl, M., Everett, M., Ford, E., Fortney, J., Gautier, T., Geary, J., Gould, A., Haas, M., Henze, C., Howard, A., Howell, S., Huber, D., Jenkins, J., Kjeldsen, H., Kolbl, R., Kolodziejczak, J., Latham, D., Lee, B., Lopez, E., Mullally, F., Orosz, J., Prsa, A., Quintana, E., Sanchis-Ojeda, R., Sasselov, D., Seader, S., Shporer, A., Steffen, J., Still, M., Tenenbaum, P., Thompson, S., Torres, G., Twicken, J., Welsh, W., & Winn, J. (2013). Kepler-62: A Five-Planet System with Planets of 1.4 and 1.6 Earth Radii in the Habitable Zone Science DOI: 10.1126/science.1234702