Except for the telescopes, the landscape up here is empty, an earth of raw brown-black that doesn't give off dust underfoot. There are no birds, no trees, no blades of grass, just the clouds and the sky and the bright orange or drab green of the hand-out parkas.

More interesting than the setting sun itself are the sunset colors reflected for a fleeting few moments on the westward sides of the stark white observatories. At the same time, off the east side of the peak, Mauna Kea casts an eerie pyramid-shaped shadow in the clouds below.

The observatories don't let the public look through their telescopes, though, and visitors aren't allowed on the summit after dark. So once the sun sets, back down the mountain we go. It's a disturbing junket on the steep, winding gravel road with sheer drop-offs, made even more harrowing because vehicles may only use their flashing hazard lights. Visiting vehicles can't use their headlights until they're back down to the 9,000-foot level at the visitor's center, the next stop on our odyssey.

Under the milkiest possible Milky Way, Greg sets up our own telescope, serves hot chocolate and chocolate chip cookies, and launches into a discussion of Mauna Kea's unique place in the universe. He says we can see a good percentage of the Southern Hemisphere's stars from here, and during certain months both the North Star and the Southern Cross are visible. He points out constellations difficult or impossible to see on the mainland, speculates on the existence of extra terrestrial life and lets us one at a time peer through the scope at famous stars, each a brilliant diamond against a black velvet sky.

Polynesian navigators, he says, once believed that each island had its own star; they had only to sail toward it to arrive. And so it was that some 1,600 years ago, expeditions set forth from the Marquesas.

After about a month at sea, they landed in what we now know as the Hawaiian Islands. They were followed 500 to 600 year later by groups from Tahiti and, 700 to 800 years after that, by everybody else.

The down side to Mauna Kea: Even people who've traveled without incident to high-altitude destinations on the mainland might find themselves dizzy, gasping for breath or experiencing even worse symptoms on this excursion, perhaps because here the trip is directly from sea level.

The University of Hawaii Institute for Astronomy, which manages Mauna Kea, cautions pregnant and obese travelers, those with respiratory, heart or circulatory problems and anyone under the age of 16 against going to the summit. Scuba divers are warned to wait at least 24 hours after diving before making the trip. Responsible tour operators pass those warnings along to their clients - and carry an emergency supply of oxygen, just in case.

IF YOU GO:

Hawaii Forest & Trail is only one of several means of reaching Mauna Kea. Here are some others.

DRIVE IT YOURSELF: You can ascend Mauna Kea on your own if you rent a 4WD vehicle, the only kind permitted to reach the summit. Check weather conditions before heading out. They'll close the road if the weather up top is too bad.

The decision to DIY assumes certain risks. You'll be behind the wheel in unfamiliar circumstances - steep, hairpin turns on lava-gravel surfaces - and under the influence of an extreme change in altitude from sea level to almost 14,000 feet. (I've traveled to the higher altitudes of Rocky Mountain ski areas and even to Pike's Peak and never experienced the light-headedness and dizziness that I did on Mauna Kea. I attribute that to the fact that in the Rockies, I started out at a higher elevation, whereas on Hawaii I was starting from sea level.) On the ascent, plan to stop at the visitor center for an hour or so to allow your body a chance to acclimate . If you go up to watch the sunset, you'll be driving back down to about the 9,000-foot level to the visitor center in the dark with only your flashing hazard lights to show you the way. Only from there on down can you use your headlights.

BY HELICOPTER: Impossible. They can't land there.

GUIDE SERVICES:

Mauna Kea Summit Adventures: The Sunset and Stargazing Tour ($185, tax included) departs from several Kona-side locations in big-windowed mini-coaches and lasts eight hours or so. Their professional guides use 11-inch Celestron telescopes and laser pointers for the star party. They provide parkas and serve a hot picnic dinner with choice of entrees. (888-322-2366; www.maunakea.com)

Hawaii Volcano Tours: The Mauna Kea Summit tour ($165, tax included) picks you up and drops you off at your hotel or ship in seven-passenger SUVs. Their guides provide parkas and serve dinner and snacks during the evening. (808-966-6620; www.lavatours.com)

Arnott's Lodge and Hiking Adventures: Arnott's Famous Mauna Kea Hike - Sunset and Starshow ($70 for lodge guests; $110 otherwise) takes about nine hours and departs from Hilo, making a grocery stop on its way to the visitor center for a half-hour acclimatization break. They make time at the summit for a short hike to it highest peak before retuning to the visitor center for a star party where the guide hands out binoculars and directs attention with a laser wand. You bring your own warm clothing and buy your dinner at the grocery stop. (808-969-7097; www.arnottslodge.com)

INFORMATION: Contact the Onizuka Center Visitor Information Station, 808-961-2180; www.ifa.hawaii.edu/mko. For weather reports call 808-935-6268.

Toni Salama: tsalama@tribune.com

© 2007, Chicago Tribune.