‘No shadow day’: Big Island gets one more chance to experience Lāhainā Noon this year

Shadows beware. The sun is coming for you.

Two days a year, in May and July, our solar system’s star passes directly overhead of the Earth at a 90-degree angle in locations between 23.5 degrees north of the equator and 23.5 degrees south, a swath around the plant known as the tropics. This causes upright and smooth-sided objects such as flagpoles and soda cans to be “shadowless.”

As the only U.S. state located in the tropics, Hawaiʻi is the only one that experiences this unique astronomical event called Lāhainā Noon — and it’s happening again on the Big Island next week.

Waimea will be “shadowless” at 12:29 p.m. on July 23, followed by Hilo getting in on the action at 12:26 p.m. on July 24.

On the west side of the island, Lāhainā Noon will happen at 12:30 p.m. on July 25 and at 12:29 p.m. on July 28 at South Point. Timing varies because of the east-west and north-south alignment of the islands and each location’s longitude.

All other Hawaiian islands already experienced it a second time earlier this month.

“The science of Lāhainā Noon relates to the science of the seasons,” said Emily Peavy, senior planetarium educator and technician at ‘Imiloa Astronomy Center of Hawai‘i in Hilo.

The phenomenon happens when the sun reaches solar noon as it passes the meridian — an imaginary line going from exact north to exact south in the sky. For less than a minute, certain objects do not cast shadows. People and other “bumpy” objects will see their shadows, but only directly under them.

Lāhainā Noon occurs about a month before and a month after the summer solstice, usually on June 21. In July, the sun’s sub-solar point, the location where it is directly overhead, moves from north to south through the islands. After the winter solstice, usually about Dec. 21, the sun’s sub-solar point begins to move north again, so in May, the islands experience Lāhainā Noon from south to north.

“You can kind of imagine the sun bouncing back and forth between the tropical lines,” Peavy said, adding because of the tilt of the Earth, the tropics are the only places that recieve direct sunlight all year round.

Other places around the globe that experience these twice-annually moments include Puerto Rico, Guam, American Samoa, Ecuador and Chichén Itzá in Mexico, where some temples are aligned to the “zenith sun,” another name for Lāhainā Noon. Places along the equator experience the event on the spring and fall equinoxes.

Locations in the southern hemisphere experience it during the opposite times of year as seasons are reversed. On the Tropic of Cancer, the northern most latitude of the tropics, and the Tropic of Capricorn, the tropics zone’s southernmost border, only experience one each year in June and December, respectively.

Also called “no shadow days,” the Bishop Museum in 1990 had a contest to give the phenomenon a name and the winner was Lāhainā Noon. While it shares its name with the community on Maui, there’s no connection. The Hawaiian word “lāhainā” translates to “cruel sun” in English, but it also references severe drought in that part of the island.

According to the museum’s Jhamandas Watumull Planetarium, an older Hawaiian term for the event is “kau ka lā i ka lolo,” which can be understood as “the sun rests upon the brain.” The planetarium says on its Lāhainā Noon webpage that the phrase not only references the special “no shadow” times, it also alludes to its cultural significance.

“The phrase references high noon, when the sun is directly overhead and the shadow [or aka] retreats into the body,” the website says, referencing the 1979 book “Nānā I Ke Kumu, Volume 1″ by Mary Kawena Puki. “In Hawai‘i and in other parts of the Pacific, the poʻo [or head] is a sacred part of the body, and actions or rituals involving the head are very significant.”

High noon also was thought by ancient Hawaiians as a time of great spiritual power. Aka as shadow is understood to be closely connected with a person’s spirit, so during these special times of year, certain rituals might have been planned or other cultural and even medicinal acts done to maximize their delivery.

Peavy said the best observing conditions for Lāhainā Noon — and disappearing shadows — are clear and sunny. If there is cloud cover, the effect is not as great due to dimmer sunlight making shadows more difficult to make out.

“It’s hard to predict where on island will have the clearest skies,” she said.

The Friends of Liliʻuokalani Gardens is hosting a Lāhainā Noon viewing event from 11:30 a.m. to 1 p.m. on July 24 in Hilo at the gardens on Banyan Drive. The forecast for Monday in Hilo looks like the weather might cooperate. The National Weather Service forecast office in Honolulu is calling for partly sunny skies with a 50% chance of scattered showers.

If you can’t make it to Liliʻuokalani Gardens, Peavy offered a couple of ideas to test the Lāhainā Noon out yourself.

Set a few objects outside, some cylindrical and others “bumpy,” an hour or two before the event starts. Check back about every 15 minutes and watch as the shadow gets smaller and smaller. You can even take a picture each time. After Lāhainā Noon, watch how the shadow gets bigger and which direction it faces.

“I’ve also seen some great things where people will cut out an image or a word in cardboard and then secure it over the ground to watch the shadow change and the word/image appear perfectly,” Peavy said.

During Lāhainā Noons of the past, she and others have often gathered around the “Voyage of the Navigator” mosaic, which is positioned exactly under ‘Imiloa’s skylight, to watch the sun light it up perfectly. No matter how many times she’s seen it, “it’s always so cool to watch.”

“It’s a fun astronomical phenomenon that can only be witnessed in some locations on Earth,” Peavy said about Lāhainā Noon. “It’s wonderful to be a part of it.”