Monthly Sky Charts for Hawaiʻi
May 2019 Skywatch
Hōkūleʻa, Arcturus in the constellation Bootes is the zenith star for Hawaiʻi, passing above the Kāʻu desert on Hawaiʻi Island. Armchair researchers have speculated that Hōkūleʻa, the fifth brightest star in the sky following the Sun, Sirius, Spica, and Alpha Centauri, may have been an object that lead early oceanic mariners in the direction of the Hawaiian Islands as they migrated from islands in the South Pacific. Based upon similar language traits, researchers believe that the original settlers of the Hawaiian Islands migrated north from the Marquesas Islands. The location of the Marquesas to the southeast of Hawaiʻi would allow for a natural westward drift by canoes migrating north under the influence of the tradewinds. On a 1995 voyage from the Marquesas, a fleet of seven deep-sea voyaging canoes were gently pushed by the tradewinds, in an off-the wind direction, towards Hawaiʻi Island.
Along with Hōkūleʻa, the star Hikianalia, Spica in the constellation Virgo, and Hōkūpā, Regulus in the constellation Leo, make up the Spring Triangle. Hikianalia rises a little south of Fatu Hiva in the Marquesas Islands making it a zenith star for that archipelago. Perhaps zenith stars were used to mark the latitudes of significant islands within Oceania, marking the sailing pathways between archipelagos.
Stretching over our heads at 8 pm will be the navigational starline of Kaiwikuamo‘o, the Backbone. This full starline stretches across the sky from Hōkūpa‘a, the North Star, to Hānaiakamalama, the Southern Cross, which will be visible in Hawai‘i right after sunset until 1 am in early May. The rusty red planet Mars remains in the northwestern region of our early evening sky.
As summer season approaches, the days will be longer and the sun will be rising earlier in the morning. Throughout May, the sun will rise around 6am. Venus will be rising in the east just before the sun and will stand out through our dawn colored sky. Both Jupiter and Saturn will be high in the south western sky at this time, accompanied by the famous curling shape of Maui’s Fish Hook.
Here in Hawai’i, we are fortunate to experience unique events called Lahaina Noons. On these dates, the sun will rise to the exact center of the sky (known as the Zenith) and will be as high in the sky as it is going to be. At the time of the zenith sun, or Lahaina Noon, objects which have smooth sides will cast no shadow on the ground. Slight changes in latitude across Hawai‘i causes different parts of the state to experience Lainana Noon on different dates, but we will all experience two Lahaina Noons; one before the summer solstice and one after. In Honolulu, the first Lahaina Noon will be on Monday, May 27th at 12:28 pm and the second will be on Tuesday, July 16th at 12:37pm. In Hilo, the first Lahaina noon will be on Saturday, May 18th at 12:16 pm and the second will be on Wednesday, July 24th at 12:26 pm. At ‘Imiloa Astronomy Center in Hilo, the round design of the mosaic floor was strategically positioned to perfectly align with the atrium’s skylight so that on Lahina Noon dates, the zenith sun will perfectly illuminate our mosaic on the floor.