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SYFY WIRE Bad Astronomy

The planets, like grains of sand

By Phil Plait
Hubble view of Sagittarius

I was recently contacted by a radio show called “Texas Standard” for an interview. Not long before, astronomers announced they had found an additional 200 exoplanets, worlds orbiting other stars, including 10 that were about the size of Earth, adding to the more than 2,000 known exoplanets already discovered. The host of the radio show, David Brown, wanted to look past the specific news a bit and ask a less proximate question: Why should we care?

This is, in fact, an excellent question. We are inundated with news of all kinds, and science news can get lost in the noise, especially when it’s incremental news, not a major new discovery but something that just adds to and reinforces what’s already known.

You can listen to the interview at the “Texas Standard” site; it’s relatively brief.

I want to talk about this a little more, because the interview was abbreviated and this is an important topic.

Why should we care about this news, or indeed any science news? As I said in the interview, it’s because we’re not automatons, trudging along our dreary lives, counting the gray minutes until we die. We are multidimensional beings, capable of seeing and doing so much more, wanting to experience wonder and joy, and curious about the Universe around us.

When we find a new collection of exoplanets, for example, it’s more than just tossing a handful of dusty old data onto a now-slightly-bigger pile. You have to get past the hype and understand what we’re doing here: Kepler is designed to look at a small patch of the sky, one you could easily cover with your thumb held at arm’s length. It looks at 150,000 stars in that patch, and over four years has found well over 2,000 planets. But there are hundreds of billions of stars in the galaxy, a million times as many as Kepler is studying.

Statistically speaking, for every planet Kepler finds, there are a million more in the galaxy waiting to be discovered.

This is profound knowledge, the sort of thing that fills the soul, opens the mind, makes us crave to understand more. This alone is reason enough to study the heavens. It stirs our passion and is no different than the drive that motivates us to create great works of art, or to ponder the deepest of philosophical questions.

There is a part of us that seeks to know more about what’s outside of us. When we gaze upward, when we train the results of our centuries-long technological and scientific ambition on the heavens, we can find those answers. It satisfies, at least in part, that itch to know more.

But there’s more to it than that. These philosophies, these desires, do not exist in a vacuum. For some, this sort of exploration demands a more materialistic impetus.

For them, note then that motivated self-interest plays into this as well. We are to the best of our knowledge the first technological civilization on this planet, and we’ve spread to every place on it, and even, in a limited sense, above it. The technology we developed to allow this is interacting with the Earth, changing its surface and atmosphere and oceans, and some of these changes are not necessarily to our benefit. We’re running a massive global experiment with no control groups.

By sending up satellites to look down on Earth we’ve discovered these changes and have been able to deal with some of them. But we don’t fully understand the way our planet works. We study it intensely, but it is the only sample of a planet like ours we can study. It would be extremely useful to have more, so that we can compare and contrast our home world’s behavior with theirs. By looking outward we can find these other planets, see how they work, and then learn more about our own.

These aren’t just words. These are actual deeds, things that we really and truly are doing and learning by studying other worlds. We’re trying to answer the biggest questions there are. Why are things this way and not another way? Why are we here? What lies ahead? But we are also hoping to answer more immediate questions: How are we changing our planet? How quickly are we changing it? What can we do to prevent these changes becoming toxic?

Certainly not all these issues will be solved, by searching for exoplanets or otherwise. But the same desire and the same means to do so —science— are by far the best paths we can take to lead to the answers we seek.

By looking outward, we look inward.

One more thing. In the interview, the host then said an interesting thing with respect to this new exoplanet finding: If you find a grain of sand, and then even another hundred grains of sand ... if you know there are billions out there, then who cares?

Ironically, this analogy does not show how these discoveries inure us to this news. It shows the exact opposite.

Imagine you’ve lived somewhere isolated, say deep in a forest. You’ve never seen a grain of sand, but you’ve wondered if they exist. Then you find one. Sand is real! That’s a terribly important discovery, and has profound implications. And then you find another one, and the next one, and the next one, and a new revelation dawns: Sand is common. And as you make a pile of them you find some are clear, some translucent, some green, some yellow, some black. They come in different sizes and shapes, and are composed of different materials. What is this telling you?

So you go exploring, and find more sand the more you look. You see more, and more, and then, breaking through the trees, you see to your utter amazement a beach stretching out before you, something you could only dream of before.

But even that is nothing compared to what lies beyond: an ocean, something you could not have even conceived of. It is beautiful, dark, vast, sweeping, its motion beguiling and enthralling. And even as you see it, you realize you’re only seeing the surface. What lies beneath?

All this because you found a grain of sand, and decided to look for more.

That is why we look for exoplanets. And that is why we do science.

[Top image: Hubble's view toward the center of our galaxy. 150,000 stars are visible here. How many have planets? Credit: NASA, ESA, K. Sahu (STScI) and the SWEEPS science team]