On the summer solstice — “the first day of summer” — in June, the sun reaches its most northerly position in the sky. On this day, the sun will be directly overhead at solar noon at the Tropic of Cancer and visible for a full 24 hours at the Arctic Circle. Solar noon is the time of the day when the sun is highest in the sky.
On the winter solstice — “the first day of winter” — in December, the sun never rises at the Arctic Circle and is directly overhead at solar noon at the Tropic of Cancer’s southern counterpart, the Tropic of Capricorn.
Between the Tropic of Cancer and the Tropic of Capricorn is what we call the tropics — one of three major regions defined by the three special circles of latitude mentioned earlier along with the Antarctic Circle. For the record, the other two regions of earth are the temperate regions mentioned earlier and the polar regions: those locations above/below the polar circles.
In the tropics, like Hawaii, the sun will pass directly overhead, a phenomenon known in astronomy as “passing through zenith,” all locations between the two tropical circles twice. These passes will occur on either side of any given solstice. Here in Hawaii, these passes are called Lahaina Noon.
Lahaina Noon is a term coined by the Bishop Museum in 1990 to describe this zenith solar noon. The name was chosen because in the Hawaiian language, la-haina translates to “cruel sun.”
So what makes Lahaina Noon special? What is there to observe? When Lahaina Noon occurs, because the sun is at zenith, vertical objects cast no shadows. Think of a parking meter or a vertical lamppost; these objects will not cast shadows since the sun is directly overhead. Ancient Hawaiians described this as kau ka la i ka lolo, which roughly translates to “the sun rests on the brains.” According to a 2010 article in the Honolulu Star-Advertiser, “It was believed that the moment in which the sun passed over the zenith causing a person’s shadow to disappear was a time of great personal power. At this moment the person’s mana would collect inside, and the person would be aligned with the forces of the universe.”
In the Northern Hemisphere, as we move towards the summer solstice, the sun slowly marches north. Each day, the sun is a little further north in the sky. Of course, this is only our perception: in reality it is us, the earth, that is moving. This movement of the sun is obvious when we look at the times for Lahaina Noon since this phenomenon occurs at later dates for more northerly locations than for southerly ones.
Here are some dates and times for Lahaina Noon here on the Big Island:
• Waimea: July 23 at 12:29 p.m.
• Hilo: July 24 at 12:27 p.m.
• Kailua-Kona: July 24 at 12:30 p.m.
• Waikoloa Resort: July 23 at 12:30 p.m.
• Hawaii Volcanoes National Park: July 23 at 12:27 p.m.
• South Point Lighthouse: July 28 at 12:29 p.m.
• Mauna Kea Summit: July 24 at 12:28 p.m.
• Kamehameha Birthplace, North Kohala: July 21 at 12:29 p.m.
These dates and times also reveal something else: the sun’s highest position in the sky occurs at what astronomers call solar noon. We can see from the times above that solar does not coincide to our “observed noon,” at 12-noon. This is simply because our observed noon is a product of our human-made time zones. In reality every location has a slightly different solar noon than any other locations to the east or west of it. If every line of longitude had a different slightly different clock, it would be very difficult to conduct the activities of the modern world. The advent of time zones, had the effect of disconnecting solar noon from observed noon.
Here on the Big Island, our clocks are actually the “most correct” since we are closer than any of the other islands in the state to the 150°W, which is the line where solar noon occurs exactly at observed noon and is accordingly, the center of our 10:00 time zone. If you want to calculate the time for Lahaina noon at your specific location you can check out the NOAA website at www.esrl.noaa.gov/gmd/grad/solcalc.
