by Sarah Scoles

Astronomers have found the first Earth-sized planet (and the smallest planet found so far) around a Sun-like star. And not just any Sun-like star--the closest Sun-like star, Alpha Centarui B. Which also happens to be the closest star. Period.

There it is. See it? (Credit: 1-Meter Schmidt Telescope, ESO).

Though this planet is very close to the star, and so is too hot to harbor life, where there's one planet, there tend to be more that we just haven't found yet. And, presumably, one of those could be in the star's habitable zone.

Today, ESO scientists Dumusque, et al., released a Nature paper announcing the exoplanetary discovery. It took four years of research and 450 separate observations, but they found a rocky (not gaseous, like Jupiter and Saturn) planet that is only 4.4 lightyears away. In astronomical terms, as Dr. Geoffrey Marcy of UCBerkeley said, "close enough you can almost spit there."

Which, of course, makes us want to spit there. Or, more precisely, spit a probe there.

Are We Talking about Space Travel?

Although those 4.4 lightyears represent a distance that make current space vehicles shake their heads vigorously and run away, astronomers (at least those quoted in the New York Times article) are considering action.

Sara Seager, an astronomer at the Massachusetts Institute of Technology, said in an e-mail, "I feel like we should drop everything and send a probe there to study the new planet and others that are likely in the system." ... It could take hundreds of years, but such a mission, Dr. Marcy said, could jolt NASA out of its doldrums.

Rarely, in my opinion, do we see astronomers making such go-getter statements, especially ones that sound rather sci-fi. Astronomy (excepting solar system science) is based on collecting photons and/or thinking about what would happen if photons were collected. It is the most hands-off (in terms of actual hands) science that exists, since almost all of the I have the greatest idea. Let's go there in Cylon ships. subjects and "experiments" are hundreds if not thousands if not millions if not billions of light-years away. That doesn't make it less real or less important. But it can make it harder for people to connect to.

It appears to make a difference, to excitement level, if we can reach out (with an ion drive or a solar sail or, more likely, technology we haven't thought of yet) and touch things: be in things, on things, around things, at things.

And I think maybe we're seeing that with scientists, too, and with the science journalists. After all, almost all articles about this discovery end with the question "So could we GO THERE?"

While it's awesome and important to learn about black hole spin and giant molecular cloud collapse, that's not what really gets into people's blood, makes them dream, and makes them okay with spending lots of money on projects with only long-term payoff.

What fires people up is still exploration. Going and doing. There may not be any more continents to "discover," but there are other stars. And apparently, around those other stars, there are planets. Like ours.

When People Like Astronomy the Most

People also tend to be most interested in astronomical discoveries that can be categorized in terms of how they compare to our experience.

Wow, that's foreign to my everyday experience (see: black holes, dark matter, dark energy: the perpetual favorite astronomical topics). Wow, that reminds me of my everyday experience (see: greenhouse effect on Venus) Wow, that is a lot like where we live (see: this discovery). Wow, that's a lot different from where we live (see: diamond planet). Wow, that's extremely far away from us (see: most distant galaxy). Wow, that's extremely close to us (see: this discovery).

So to find a planet that is our planet's size (even if it's too hot and there's no promise that there's a planet in the habitable zone), around a star our star's size, in the closest spot it could possibly be--that makes our little, us-centered brains fire with possibilities. And it makes the parts of our brains that led us to cross the Bering Strait and the Wild, Wild West and the stratopause say, "Let's GO TO THERE. I will help with my tax dollars." Yep, it really says "Robot Alert"(Credit: Ace Double Press, illustration by Jack Gaughan.)

The Big Questions

What makes people excited about astronomy are big questions that relate to us and our experience: How did the universe start? How will it end? What laws govern the universe? How do those laws lead from unstructured plasma to atoms to galaxies to the intelligent life here? Has life arisen elsewhere? Etc. Many basic astronomical research questions ( like "How/why do stars form?") are under the us-centered questions.

We should take advantage of the scientific and personal excitement surrounding this discovery. Since Kennedy's lunar call-to-action, there hasn't been a space-based initiative that captured imaginations, inspired both adults and kids, pushed technology forward, transcended fiscal years and election years to the same degree. Think of what we did in those 8 years. Think of what we could do if someone said, "Hey, listen. Let's start work on this project where we decide to send something to Alpha Centauri. Let's throw a bunch of money and smart people at it and say, 'Hey, people of the world, we are going to send something TO ANOTHER STAR where there are PLANETS.' It's going to take a while to figure it out, but we can do it."

It would be a shame not to harness the people-power that a discovery like this can have. It would be a shame to leave everyone's oh-so-human exploratory yearnings yearning. Or, as Dr. Marcy phrased positively, "What a great scientific educational mission to have a probe out there, making its way decade after decade.”

It is rare that a new scientific discovery has the same transcendent effect on me now as my early childhood discoveries about the universe (which were only new to me) did. While imagining myself as an astronaut, dreaming about the aliens that I knew were trying to talk to me specifically, and jumping up and down while my mom was talking to my aunt on the phone and making me wait to tell her, "Did you know the sun is a STAR?"--while none of those actions results in successful NSF grant proposals or ApJ papers, true childlike excitement and awe do have their place in science. The planet-next-door discovery, and the widespread question "Time for spaceships?", took me back to the time when excitement and awe overshadowed all other reactions, but with the slightly more mature understanding of the work behind the discovery, and the work needed to go foward from there.

Summary/Analysis Articles

For an insightful overview of the scientific process behind the discovery, check out Phil Plait's post "Alpha Centauri Has a Planet!" in which he uses the phrase "Holy crap" and references Lost in Space.

Adam Mann at Wired covers the story with the twist of describing what the system would look like if we went there and what a Centaurian day would look like to a Centaurian, or to a human visiting a Centaurian planet.

EarthSky gives detail about the instrument that scientists used to discover this planet . It's called HARPS--the High-Accuracy Radial Velocity Planet Searcher.

Space Travel Articles

While it would take 40,000 years to get to Alpha Centauri with current technology, that's because we haven't put a lot of effort (or cash money dollars) into the specific problem of getting really far away from where we live.

There are some programs that are investigating or have investigated the problem of interstellar space flight.

The 100-Year Starship initiative is funded by NASA and DARPA, everybody's favorite scary/supersecret governmental department, and uses crowd-sourcing to get the best ideas for the planning of a long-term space exploration program. As their site says

Space exploration will most likely stagnate if it reflects an exclusionary posture that only some small set of people can fathom, let alone hope to participate. The public has never lost their fascination with space, they have, however, been left out.

NASA's Breakthrough Propulsion Physics Project and the expensive textbook it produced, Frontiers in Propulsion Science, are good starting points for reading about the current(ish) state of rocket propulsion and where it is headed.

The feature article in July 2012's issue of Astronomy discusses exactly the topic of getting to Alpha Centauri.

Dumusque, X., Pepe, F., Lovis, C., Ségransan, D., Sahlmann, J., Benz, W., Bouchy, F., Mayor, M., Queloz, D., Santos, N., & Udry, S. (2012). An Earth-mass planet orbiting α Centauri B Nature DOI: 10.1038/nature11572