On March 20 the sun crossed north over the equator in an event called the equinox, a juncture when daylight and nighttime are about equal in length, heralding the beginning of spring in the Northern Hemisphere. The Hawaiian word associated with this season is Kupulau (Sprouting Leaf).
Today we return to learning the night sky through the eyes of oceanic voyagers by examining the second Hawaiian starline, Kaiwikuamo‘o, which stands out during spring and early summer.
Starlines are collections of bright stars and constellations that line the night sky in a north-south direction. In the Hawaiian star chart, the four starlines are, Kekaomakali‘i (Bailer of Makali‘i), Kaiwikuamo‘o (Backbone), Manaiakalani (Heavenly Fishing Line) and Kalupeakawelo (Kite of Kawelo). Because each is most prominent at a different time of year, they also serve as seasonal markers for winter, spring, summer and fall.
In January’s column, we introduced the first starline, Kekaomakali‘i, prominent during the winter season. The third starline, Manaiakalani, will be presented this summer and the fourth, Kalupeakawelo, this fall.
The easiest constellation to identify in the Kaiwikuamo‘o starline is Nahiku, the Big Dipper, rising in the direction manu ko‘olau, northeast on our star compass. The seven stars of Nahiku form the shape of a celestial ladle. Drawing an imaginary line from the two pointer stars in the scoop to the horizon will lead you toward Hokupa‘a (Polaris), also known as the North Star.
Hokupa‘a is near the north celestial pole, so it seems motionless while other stars appear to rotate around it. Hokupa‘a is part of the constellation the Little Dipper, which resembles a second smaller celestial ladle. These two buckets (Big and Little Dippers) are said to be pouring into each other.
Follow the handle of Nahiku east to arrive at the fourth brightest star in the night sky, Hokule‘a (Arcturus). Hokule‘a rises in the star compass direction ‘aina ko‘olau (east-northeast), passing directly over Hawaii island and is the zenith star (star at the highest point on the celestial sphere) for the Hawaiian islands. Following Hokule‘a la malanai (southeast) brings you to Hikianalia (Spica), in the constellation Virgo. Hikianalia is actually two stars, a blue giant and a variable star, that orbit each other too closely to separate visually.
Continuing southward around the star compass, you will see a celestial quadrilateral shape, a box with a short and a wide end, known as Me‘e (Voice of Joy) to oceanic voyagers and Corvus (Latin for crow or raven) to astronomers. Taking a line through the center of Me‘e toward the southern horizon leads to a constellation held in special regard by Pacific navigators: Hanaiakamalama (Cared for by the Moon) or the Southern Cross, which rises around 9 p.m. in April.
Navigators can use Hanaiakamalama to determine the direction of hema, south. This constellation is also important for establishing the latitude of the Hawaiian islands. When Hanaiakamalama is in the upright position, about 11 p.m. in April, you can measure the distance between its top star and bottom star — when the distance between the bottom star and the horizon beneath it is equal, you know you are at the latitude of Kahoolawe. At that point, simply turn your canoe downwind, and the wind will sail your canoe toward Hawaii.
Early mornings
Between 3 a.m. and 6 a.m. toward the south-eastern sky of April 2, Mars and Saturn will go through a conjunction — when celestial objects appear close together (within a few degrees). A planet will frequently conjunct with celestial objects as well as other planets. The red dot of Mars will appear close to the faint yellow dot of Saturn.
Every year in April, when Earth passes through Comet Thatcher’s dusty tail, a meteor shower, the April Lyrids, occurs. This is the oldest known shower, chronicled in the Zuo zhuan (ancient Chinese narrative history) in 678 B.C. This year’s Lyrid meteor shower is April 16 to 25, with prime viewing just before sunrise on April 22. At its peak, you can expect to see about 20 shooting stars an hour.
At 4:44 a.m. April 29, Mercury will be visible until the light of dawn obscures it. The planet will be at a unique position in its orbit, known as the Greatest Western Elongation, and its farthest position from the sun in the eastern sky.
All April, sunrise is between 6 and 6:30 a.m. During these hours the planets of Jupiter, Saturn and Mars will be high in the southern region of the sky. Sitting between the planets will be the beautiful bulge of the Milky Way galaxy.
April’s night sky
In early evening the incredibly bright Venus will chase the sun into the horizon. Venus, the third brightest object in the sky after the sun and the full moon, is usually seen just after sunset or immediately before sunrise and so is variously referred to as the evening star or the morning star.
The recognizable shape of Kaheiheionakeiki (The Cat’s Cradle), also known as Orion the Hunter, will be preparing to set into the west. On a dark night, you’ll be able to see the blur of the Orion Nebula beneath the famous three stars that cut across Orion’s Belt. The Orion Nebula is the most famous stellar nursery in the sky.
Chad Kalepa Baybayan is navigator-in-residence and Emily Peavy is planetarium technician support facilitator at ‘Imiloa Astronomy Center of Hawai‘i at the University of Hawaii-Hilo.
