Friday is supposed to be an end-of-the-year fun day for ‘Iolani School’s sixth-graders, but social studies teacher Catherine Fuller will use the opportunity of a "Lahaina Noon" to give her students a little lesson in latitude, longitude and the Earth’s relationship to the sun even as they’re playing at Kaimana Beach.

"It’s a plus that we’re the only place in the United States that will get to see a Lahaina Noon," Fuller said Wednesday.

Lahaina Noon occurs twice a year in the tropics, and Hawaii is the only state in the union where shadows all but disappear for three to five minutes as the sun burns directly overhead.

So at exactly 12:28 p.m. Friday, Fuller plans to have all of ‘Iolani’s 120 sixth-graders at Kaimana Beach stop and take notice that nothing will cast a shadow.

At the same moment across the island, Mililani Middle School eighth-grade earth and space science teacher Peter Lucas will have about 100 students around the school’s flagpole watching the pole’s shadow disappear.

"I’ve found that most kids — and adults — don’t know what’s happening," Lucas said.

The sun has been making shadows disappear in the islands twice a year long before written history. But the phenomenon didn’t have a catchy title until the Bishop Museum sponsored a contest in 1989 that resulted in the term Lahaina ("cruel sun") Noon.

"Before that, people just called it ‘Shadowless Noon,’ ‘High Noon’ or ‘The Day That the Sun Goes Directly Overhead,’" said Melody Chang, a Bishop Museum planetarium presenter who will give a special program on Lahaina Noon on Friday atop the museum’s observation deck, which sits above the planetarium lobby.

As a child growing up in Kaneohe, Chang, 28, remembers days when she momentarily did not cast a shadow.

It wasn’t until she took an Astronomy 110 class at Windward Community College in 2003 that Chang realized the phenomenon had a catchy name — Lahaina Noon — and a scientific explanation.

Now she’s happy to share the experience with the 40 to 70 children and adults who Chang expects will show up for the museum’s Lahaina Noon program.

"I agree that most people in Hawaii don’t know what it is," Chang said.

She’ll use a pole to illustrate the effects of a Lahaina Noon, as well as sundials that will read noon because of the sun’s proximity to Honolulu — instead of the actual time of 12:28 p.m.

The simplest explanation is that the sun will be positioned directly over Oahu beginning at 12:28 p.m. and "everything vertical — a telephone pole, a building and your own body — will not cast a shadow," said Andy Owens, Bishop Museum’s science education manager. "It just so happens that in Hawaii the sun is in the perfect alignment you really need to not cast a shadow or have any shadow effect."

For Lucas, Friday will be the culmination of his Mililani Middle School students’ year-round study of the sun’s relationship to their planet.

"Most of the kids get it, but they can’t really get it with just models," Lucas said. "It’s a phenomenon that’s hard to imagine. Our kids are lucky enough to live it."