I was fortunate to be able to visit the Keck Observatory on Mauna Kea during a recent short holiday in Hawaii. It is an inspiring place. Thanks to the fantastic advances in adaptive optics technology, as well as the observatory's new laser guide system, this ground-based telescope is now truly competitive with Hubble.

Here is one example of these advances: the Keck Observatory is one of the world centers for the search for extrasolar planets. It was not many years ago that research in this field was a subject without subject matter.

Scientists speculated about the existence of planets around distant stars, but not one was known to exist. Today, when I talk to some elementary school classes and ask how many planets there are, half the students are able yell "more than 100!" (Today the number is actually more than 250).

So it should have been no surprise to sit at the Keck control console and find Geoff Marcy, one of the most successful of all planet hunters, using the telescope to search for more planets around distant stars. Actually Geoff was physically located in his laboratory at the University of California in Berkeley, California - but these days observing with a telescope can be done from anywhere in the world.

The remote hook-up and video/audio communications were so good that as soon as I sat down he said, "Hi, Lou," and I was able to say, "What are you looking for?" He said he was looking for terrestrial-type planets around other stars. Terrestrial!

Indeed, we are on the verge of discovering the first terrestrial extrasolar planet, and we are probably only a few short years away from detecting many of them and characterizing their different features.

In the 1990s when Dan Goldin and Wes Huntress started getting NASA into this field, I thought such results would take a century. In a few years, when the Kepler mission starts searching for extrasolar planets alongside the Keck and other Earth-based telescopes, we'll see the beginning of whole new scientific fields: "comparative solar-systemology," and the "habitability of other worlds," and perhaps others as well.

The Planetary Society is collaborating with Marcy on creating a catalogue of extrasolar planetary systems. This will aid researchers in preparing for this onslaught of data, and help the public understand what scientists are doing. Will the new discoveries also enhance our long-time efforts to find extraterrestrial life?

Certainly they will help us understand the evolution of planets and the development of conditions suitable for life. These include the presence of water, volatiles, atmosphere, nitrogen, oxygen, etc. The greatest unknown factor is the likelihood that simple (single-cell) life will evolve into to complex multi-cellular life-forms.

I believe that what we learn about planet habitability in the next quarter-century will at least hint, if not clearly tell us, about the presence of life on other worlds.

From indications of life on other worlds to conclusions about intelligent life, or ETI (extra-terrestrial intelligence), is still a big leap. The "I" in SETI presupposes intelligent beings that would make use of communications technology, just like us Earthlings. SETI's success may even depend on aliens deliberately thinking about us and pointing their transmissions towards us.

Fortunately the "S" in SETI - the "Search" - is not too expensive and is something that The Planetary Society can do something about. We have been doing so for two decades: first with radio SETI, and now with radio and optical searches.

An even bigger leap into the future is interstellar travel. As we were chatting during his observing run, Geoff Marcy asked me about our solar sail project.

I didn't immediately understand his interest until he said that in addition to his main work searching for extrasolar planets, he and Andrew Howard were also conducting a small program from the Lick Observatory of the University of California to search for potential laser beacons being used by an extraterrestrial civilization.

Andrew, you may recall, worked with Paul Horowitz on our Planetary Society Optical SETI telescope before going to Berkeley.

Geoff knew of the idea that such powerful lasers (thousands of gigawatts) could be used not just for communications but also to drive light-sailing spacecraft on interstellar journeys.

This idea is at the core of our assertion that solar sailing is the only known propulsion technology that can lead to interstellar flight. So I encouraged Geoff to find not just an extraterrestrial communicating civilization, but a traveling one!

The enormous difficulty of interstellar travel was brought home to me (again) in Hawaii by Jon Lomberg, our longtime Society advisor and friend, who has created a beautiful Galaxy Garden south of Kona in Hawaii. Having long specialized in galaxy paintings, Jon has now created a 3-dimensional garden depicting the structure of the Milky Way galaxy in remarkable detail.

The vastness of the distances we would have to cover for interstellar travel is made very obvious in such a model. This makes merely communicating with other civilizations seem much, much easier.

Don't be confused - this was not a working vacation in Hawaii, I got to play some in the ocean also. But it is hard to stop thinking about our place in the Universe.