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Kekemapa (December) Sky Watch

by Imiloa Astronomy Center on November 27th, 2017

By Chad Kālepa Baybayan & Emily Peavy, ‘Imiloa Astronomy Center of Hawai‛i

Mastering any skill takes passion and a commitment of time. Once achieved, a skill can last a lifetime of practice, but it is accessible only to the master unless it is passed on to others. Such is the story of the Satawalese star compass, Pa‘afu, used by the late master navigator, Mau Piailug, and our more modern Hawaiian star compass created by master navigator, Nainoa Thompson.


Born to the given name of Pius Piailug in 1932, Piailug was raised in the village of Weiso on the tiny coral atoll of Satawal in the Yap State of the Caroline Islands, part of the Federated States of Micronesia. At age five, Piailug attended Weriyeng, one of the last two schools of traditional navigation, for apprentice navigator training and went on to study with Angor, a skilled and recognized master navigator. At the age of eighteen, Piailug was initiated into the rank of Palu, master navigator, through a generations-honored ceremony called Pwo. For the next fifty years Satawal would not witness another Pwo ceremony until 2007, when five Hawaiian and eleven Satawalese men were initiated.


Piailug’s penchant for sailing in all weather conditions earned him the name “Mau” from the Satawalese word maumau, meaning strong. Piailug trained and mentored native Hawaiian master navigator, Nainoa Thompson, who in turn developed a modern system of wayfinding, or non-instrument navigation, using the Hawaiian star compass.

The Hawaiian star compass is comprised of 32 houses spaced equally at 11.25˚ intervals around the circle of the horizon. Both compass systems, the Satawalese and the Hawaiian, feature “arriving” horizons (hikina-east) and “entering” horizons (komohana-west). The arriving horizon, east, in the Pa‘afu system is named for stars and given the prefix, Tan. The entering horizon, west, is identified with the prefix, Tupul.


The Hawaiian star compass uses a star’s declination to position the stars along the edge of the star compass and to identify what house it rises and sets in. In astronomy term declination in astronomy is comparable to geographic latitude projected onto the sky, called the celestial sphere, and is measured in degrees north (+) or south (-) of the celestial equator, not exceeding 90˚, the northern and southern most point of the celestial sphere. The star Hōkūle‘a, Arcturus, rises and sets at +19˚North of the celestial equator, rising near the center of the star house ‘Āina Ko‘olau and setting in ‘Āina Ho‘olua. The star Hikianalia, Spica, rises and sets at -11˚ South of the celestial equator, rising from the center of the star house Lā Malanai and setting in Lā Kona. Mintaka in Orion’s belt with a declination of 0˚ rises in the star house Hikina and sets in the star house Komohana as it lies on the celestial equator. Nainoa Thompson incorporated a working list of 110 stars to the building of his Hawaiian star compass.


The reason a star compass works so well for the latitudes between Hawai‘i and Tahiti is because we inhabit an area of ocean known as the Tropics, between the margins of 23.5˚ North and 23.5˚ South, between which the rising and setting paths of the stars, sun, moon, and planets appear to be fairly vertical. However, when we travel further north or south the paths of these objects become more inclined until they become parallel to the horizon at the poles.  Thus, at the latitudes of the far north or south, wayfinders need to reply on other techniques. The Inuit of the arctic north, for example, use a traditional system called sastrugi, in which they determine direction based on observation of snow-formed ridges on the surface of ice, shaped by the wind.


December’s night sky

On December 3, be on the lookout for a supermoon, which is when the full moon’s distance is closest to earth, at a special location on the moon’s orbit known as perigee. The moon does not orbit around earth in a perfect circle; it orbits in an ellipse or oval shape, which means that the moon’s distance from earth changes as it orbits. Every month the moon passes through perigee and when a full moon lines up with the perigee, it’s called a supermoon and will appear to be slightly larger in the sky.


Rising from the east, throughout December, will be the distinctive star cluster of Makaliʻi, also known as the Pleiades. This stellar open cluster stands out with its seven brightest stars being clearly visible to the naked eye. The stars in the cluster were all born from the same nebula about 100 million years ago. As these stars are around the same age, the cluster can be used as a laboratory for the study of stellar evolution.


Considered by many to be the best meteor shower of the year, the Geminids Meteor shower runs from early to mid-December. Multiple meteors per minute are expected to be occurring on the night of December 13, marking the peak of the shower.


Winter Solstice for the northern hemisphere takes place on December 21, where the sun will rise and set at its southernmost position in the sky. The sun will have a low arc across the sky, making it the shortest period of daylight for the whole year.


Early-morning observation

Daylight in December arrives later as the sun rises just after 6:40 am. In the early morning hours of 3:00 am as Mars rises from the east, the rusty red planet will be distinguishable among the sea of stars by its red-colored iron-oxide soil.  As sunrise approaches, the bright planet of Jupiter will rise from the east at about 5:00 am. As the 4th brightest object in the sky (after the sun, moon and Venus), Jupiter will still be visible as the sun begins to rise.  Jupiter owes its brightness to its thick atmosphere which reflects back much of the light that comes from the sun.


In the northeast the seven stars of Nahiku, which shares the same stars of the Big Dipper, are easily noticeable. Tracing the arc of stars representing the Big Dipper’s handle down towards the east, one can find the bright star Hokule‘a (Arcturus). This star is the namesake of the famous Hawaiian voyaging canoe which completed its worldwide voyage earlier this year.


December moon phases

Full Moon: 5:47 am HST, Sunday, December 3

Last Quarter Moon: 9:51 pm HST, Saturday, December 9

New Moon: 8:31 pm HST, Sunday, December 17

First Quarter Moon: 11:03 pm HST, Monday, December 25

The moon’s phase is determined by its position in relation to the sun and the earth. The designations of Full, Last Quarter, New and First Quarter refer to specific orientations of the moon, sun and earth. Listed above are the exact times the moon will be in the precise orientation; however the moon will not necessarily be visible in Hawai‘i’s sky at the specific time.  Due to the moon’s brightness, the best time for stargazing without its interference will be the week around New Moon (November 18).


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