'The top of the world' on the top of Hawaii

ATOP MAUNA KEA, HAWAII - If you count from sea level, we were 13,796 feet up, almost as high as Mount Rainier. Plenty high enough.

But if you count from the ocean floor? My Big Island tour group was shivering in thin air atop the Earth's highest mountain -- 33,500 feet from its waterlogged base to peak.

And that measure seemed the more meaningful, because this place seemed to have far more to do with outer space than with anything terrestrial.

As the sunset painted clouds in tropical hues, the nightly crowd of parka-clad, camera-snapping tourists looked like so many geckos swarming around a dozen enormous observatories dotting the top of Hawaii's highest peak.

The big crop atop Mauna Kea is telescopes, including the world's two largest functional telescopes, with mirrors 33 feet across, at the W.M. Keck Observatory. (By way of comparison, the Hubble Space Telescope comes in at a measly 8 feet.)

It's a bit like going to Cape Canaveral for a rocket launch. Every visitor to the summit of this dormant volcano is giddy, and not just from thin air.

"It's a very high-powered, high-level group of astronomers here," tour guide Greg Brown told our van full of visitors. "It's big science!"

The Keck Observatory alone is credited with detecting more planets outside our solar system than any other observation post, and helped in discovery of the accelerating expansion of the universe, for which astronomers earned the 2011 Nobel Prize in physics. Just seeing this place makes you feel smarter.

Other observatories at the top represent partners such as NASA, the Smithsonian and universities such as Cal Tech.

The high altitude -- above 40 percent of the Earth's atmosphere -- along with dark skies and dry, clean air attracted astronomers to Mauna Kea starting in 1964 when the state of Hawaii spent $42,000 to build the cliff-climbing road.

"Usually it's so dry up here you can't see your breath in the cold," Brown told our group as our van headed up like a plane taking off.

A strong island-wide ordinance restricting outdoor lighting helps keep astronomers happy.

But snow clouds, or any clouds, don't often cover the summit. The proportion of clear nights is among the highest in the world, and astronomers continue to pledge their allegiance to Mauna Kea: The next big thing coming here is the Thirty Meter Telescope, three times larger than any on Earth, so powerful that it will bring in to view galaxies forming at the edge of the observable universe, near the beginning of time. (Chew on that along with your macadamia-nut fudge.)

Visiting Mauna Kea is a special thrill for science buffs, but don't expect to peek through one of the big telescopes. And while most tour operators go up for sunset, the few observatories that welcome visitors close at 4 p.m.

Even in a tour van built for the steep road, it's no drive to the beach. As we climbed, Brown warned us of the hazards of altitude sickness.

"You might be short of breath, you might feel a little dizzy," he warned.

To acclimate to the elevation change, we'd stopped for a picnic dinner in cypress woods near the 7,000-foot level. Other tour groups and visitors typically stop at the 9,300-foot level at the visitor-information station at the Onizuka Center for International Astronomy, named for Ellison Onizuka, who died in the Challenger space shuttle explosion in 1986.

At the summit, we donned parkas provided by our guide. For my early-June visit, the temperature was in the upper 30s, with winds to 20 miles per hour. Fingers quickly numbed.

The combination of excitement and low oxygen seemed to transform the tour group into giggly schoolkids, gawking at the summit's moonlike landscape dotted with gleaming observatory domes.

"Oh, wow! Look at the clouds, and the clouds above the clouds!" said Shelley Burr, a Boeing employee visiting from Seattle. "You don't have words for this. It's the top of the world!"

The observatories were opening for the night. It felt like a sci-fi movie set.

It would be a shame to get up in that clear air and not wait for stars to come out. So we drove back to the visitor center, where Brown set up an 11-inch-wide telescope for our own star party, which included the Northern Star and Southern Cross in one swivel of the head.

On the dark road back to the Kona hotel strip, Brown suddenly braked the van to point out the Big Island's active volcano. " ... See that red glow? That's Kilauea!"