The Skeptics Society & Skeptic magazine

Stranger Than We Can Imagine

by Justin Trottier

To invoke a quote often attributed to the astronomer Arthur Stanley Eddington, “Not only is the universe stranger than we imagine, it is stranger than we can imagine.” Many areas of scientific exploration have led to surprising discoveries never envisioned, and the hunt for new exoplanets—worlds beyond our solar system—is a splendid example.

In Strange New Worlds, the University of Toronto astronomer Ray Jayawardhana offers a glimpse into the real and often messy way science is done, along with the exhilarating surprises thrown at pioneering scientists. No one thought the first exoplanet would be discovered around the unlikely location of a pulsar, or that gas giants would be found so far from where they are in our own solar system. Some exoplanets are so close to their parent star that they orbit in a matter of days, whereas one exoplanet that is eight Jupiters in mass, was found more than 10 times the distance of Neptune to our sun.

Jayawardhana’s own studies of infant planetary systems offers one clear surprise. Early solar systems are far more complicated, chaotic and dangerous than we thought. This discovery may have tremendous impact on our understanding of our own birthing process. Consider for example the finding that gas giant planets often migrate. Now researchers think our solar system’s own so-called “late heavy bombardment” period that occurred 600 million years after initial planetary formation, as evidenced by lunar craters, may be explained by the migration of our own planets.

While cosmology explores the earliest moments of the cosmos and abiogenesis seeks to understand the origin of life, Jayawardhana and his planet hunters are filling in a crucial middle of the story origin account. It is a narrative description of how those materials generated by the universe can find an appropriate environment—a home—where life may emerge. It is also a story of challenge that shows how lucky we are on our own planet. We see how easily worlds can be destroyed, with migrating giants and interacting young stars ejecting Earth-size objects into the void of space, or sending them spiraling into the star. It’s also a tale of triumph. Accumulated data is starting to show how common solar systems and even smaller worlds tend to be in our galaxy.

An award-winning science writer whose popular articles have been published in publications such as Scientific American and The Economist, Jayawardhana artfully blends interviews and profiles of leading researchers within his scientific narrative. Both aspects are fascinating and full of adventurous twists and turns.

If planetary systems are increasingly seen as chaotic and dangerous, such qualities might describe the enterprise of planet hunting itself. Chaotic because the nature of making observations at the limit of our equipment’s detection ability, or in which assumptions about planetary or stellar science are required, mean that there were a lot of early false starts, with lots of initial planetary candidates shown eventually not to exist.

Planet hunting was a pioneering field but also a dangerous game for those with uncertain career futures. In its early days in the 1980s there was great skepticism about whether the project was even a part of astronomy. Jaywardhana tells the story of Gordon Walker, now retired from the University of British Columbia, who watched as a senior astronomer left during a lecture he was giving on the topic. Walker’s postdoc teammate, Bruce Campbell, was compelled to leave the field for something more reliable, becoming a tax consultant. Even in the early 1990s, research groups were routinely turned down for funds, with granting agencies seeing little chance of detection improvement.

Yet, here we can see how quickly progress can be achieved in a scientific discipline. With seven planets discovered in the turning point year of 1996, everything changed. Within a mere decade planet hunters Michael Mayor and Geoff Marcy shared a major triumph, winning the prestigious million dollar Shaw Prize for astronomy in 2005, a sure sign that the field had come of age.

As Jayawardhana describes the scientific figures involved, such as Marcy and others, we see portraits of characters who are each unique and colorful, not unlike the worlds they’ve discovered. Some were portrayed with an arrogance, such as the very early character Thomas Jefferson Jackson See, who brazenly declared back in 1899 that he had found conclusive proof of a third body orbiting the binary star system 70 Ophiuchi. When a paper showed that such a system would be unstable, See rebuked the journal, which went so far as to ban him from future publication. See suffered a breakdown three years later.

The failure to relent by many researchers is nicely contrasted with the humility of Andrew Lyne, who almost achieved credit for discovering the first exoplanet in 1992. Less than a week before his scheduled talk at the American Astronomical Society, and with Nature already declaring the significance of the discovery, Lyne found an error in his data that made the planet disappear. While Jayawardhana’s depiction of this episode can show how desires might affect data analysis, this was a proud moment for science. Lyne immediately reported his error in front of a huge audience and was honored for his forthrightness.

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In Strange New Worlds we come to understand that these exoplanets also demonstrate the difficulty of doing science in areas such as planet hunting that are at the limit of our equipment’s ability to discern signal from noise, and especially where human desires to see things can affect our observations. This may be exacerbated by the emotional side of searching for worlds in the hope of eventually finding other habitable homes, not unlike the well known drama of Percival Lowell and his false readings of long straight lines on Mars as evidence of artificially constructed canals and thus Martian civilization.

But considering these equipment limits, Jayawardhana shows us that it really is remarkable what we can learn about far off worlds. We can determine not just their mass, volume, and density, but sometimes we can glean details of their atmospheric constituents, with a tantalizing possibility for seeing biosignatures. We are now at the stage of detecting planets merely a few Earth masses, so-called super-Earths. As we zero in on Earth-type planets in Earth-type orbits around sun-like stars, we are led to the tantalizing hunt for Extraterrestrial Intelligence.

Unfortunately, Jayawardhana’s book is rather short, and we’re left wishing he had commented further on the second element of its subtitle, namely the search for life. Although planet hunting is only now reaching the point of giving us information directly relevant to this area of exploration, he might have shared his own speculations on how far next generation planet exploration missions could go in providing signs of life data, or on how such missions might actually integrate elements of SETI.

We’re left eager for such comments after being shown actual pictures of other worlds. The first images of exoplanets not only serve as a symbolic vindication of the search, they have the immediate emotional appeal of seeing an object that’s really there. Jayawardhana’s closing chapters leave the reader understanding that we’re only getting started and certainly just entering the most exciting part of planet hunting.

Just this February, the Kepler team announced 1,235 planetary candidates. They require confirmation, which could take up to three years, but such data, accumulated over a mere five months, could triple the number of planets already discovered. Within this batch, 68 are Earth-like in size and 54 are within their star’s habitable zone. The estimate is that six percent of stars contain Earth-size planets. This not only gives us a general understanding that there’s a lot of real estate out there, but actually provides increasingly accurate quantities for two factors in the famous Drake equation for estimating the number of signaling ETs in the galaxy, namely f_p (the fraction of stars that have planets) and n_e (the average number of planets that can potentially support life per star with planets).

Jayawardhana’s book offers a great and cohesive synopsis of how far the field has come and leaves the reader excited about the prospect of following along as future discoveries are made. One need not be a passive observer either. Amateur astronomers such as Jennie McCormick from New Zealand are playing a role helping to confirm exoplanets discovered by gravitational lensing. The search for exoplanets has concreteness and an emotional appeal that other astronomical fields such as cosmology or the study of galaxies or black holes may lack, and even laypeople can join in through internet-based computing projects similar to seti@home. One of these, www.zooniverse.org, has users identify transiting planets from real Kepler mission data. The idea that any member of our species with internet access could assist in the discovery of a new planet, eventually perhaps one that is habitable, is sure to keep the search for exoplanets popular and bring increased attention to the role of science in exploring the big questions of our place in the cosmos.