April welcomes the spring starline, Kaiwikuamo‘o (the Backbone). Seen as a genealogy of stars, this north-south starline is best identified by the northern constellation Nahiku (the Seven), commonly known as the Big Dipper (Ursa Major). The first two stars in the bucket of the dipper, Hikukahi and Hikulua (Dubhe and Merak) point toward Hokupa‘a (Polaris), the North Star. Hokupa‘a is a variable star, meaning that its brightness fluctuates. There is a common misconception that the North Star is the brightest star, but there are approximately 48 other brighter stars.

Following the sweep of Naiku’s handle toward the east-northeast in the direction of the star compass house, ‘Aina Ko‘olau, we come to the red giant and fourth-brightest star in the night sky, Hokule‘a (Arcturus) in the constellation Bootes. Following the arc from Hokule‘a and crossing the celestial equator we next come to Hikianalia (Spica) in the constellation Virgo.

In oceanic wayfinding, Hokule‘a is the zenith star for Hawaii, and passes directly over Kau on Hawaii island. Hikianalia passes just south of the Marquesas Islands. To the west, between Hokule‘a and Hikianalia, is the star Kau‘opae (Regulus) in the constellation Leo. To the naked eye Kau‘opae appears as a singular star, but it is a a system of four stars organized into two pairs. These three stars make up the Spring Triangle.

Following the arc toward the south, the next constellation is Me‘e, a trapezoid constellation also known as Corvus. Drawing a line through the center of Me‘e and down toward the southern horizon, we come to Hanaiakamalama (“cared for by the moon”), also known as the Southern Cross. This constellation is important for establishing the latitude of the Hawaiian Islands. The navigational technique employed for this is called equidistant pairs. When the cross is upright or on meridian (in April it will be upright between 11 p.m. and midnight), the distance between the upper star, Kaulia (Gacrux), and the bottom star, Kamolehonua (Acrux), is 6 degrees, or approximately 2-1/2 fingers in width. When there is equal space between the upper and lower stars of the Southern Cross (at its upright position), and the space between the lower star and the horizon is equal, you are at the center latitude of the Hawaiian Islands.

To the east of Hanaiakamalama is the constellation Nakuhikuhi, the Pointer Stars that show the direction to the Southern Cross. Nakuhikuhi consists of two stars, Kamailemua (Beta Centauri) and Kamailehope (Alpha Centauri). Kamailehope is the third-brightest star in the night sky and is the closest star and planetary system to our solar system. Both Alpha and Beta Centauri are triple star systems, appearing to the naked eye as one star even though three separate stars comprise them. The Southern Cross and Pointer Stars will be visible after 10 p.m. in April.

Evening observations

While Kaiwikuamo‘o rises in the east at 8 p.m., Kekaomakali‘i (the Bailer of Makali‘i) will be setting in the west. The stunning open cluster of Makali‘i (Pleiades) will be setting in Manu Ho‘olua in the early evening. Also setting into Komohana will be the recognizable shape of Heiheionakeiki (Orion, the Hunter). As the belt of Orion lies on the celestial equator we can observe Orion setting exactly in Komohana. The larger arc of the Bailer will stretch over our sky going from Hokulei (Auriga), through Nanamua (Castor) and Nanahope (Pollux) to Puana (Procyon) to ‘A‘a (Sirius) and finally down to Keali‘ikonaikalewa (Canopus).

In the midst of the setting starline is the dynamic planet Mars, which will stand out in the sky with its distinctive reddish color.

Near the end of April, observers will be able to catch the Lyrids meteor shower, which peaks on April 22. This annual meteor shower is the result of the long period comet C/1861 G1 Thatcher passing through the inner solar system, and averages around 10 shooting stars an hour at and near its peak.

Morning observations

At around 5 a.m., the bright planet Jupiter will be high in the Southern sky as it sits right in front of the bulge of the Milky Way. To the east of Jupiter will be the fainter planet Saturn. At the same time, the planets Mercury and Venus will begin to rise out of Manu Malanai. The intense brightness of Venus makes it easy to spot and its frequent proximity to the horizon makes it the object that is most frequently mistaken for a UFO. Mercury will be just beneath Venus and the best morning to observe Mercury will be on April 11, when the planet is at its greatest western elongation.

APELILA (APRIL) SKIES AT 8 … by on Scribd

Chad Kalepa Baybayan (Kalepa.Baybayan@hawaii.edu) serves as navigator-­in-residence and Emily Peavy (Emily.Peavy@hawaii.edu) as planetarium technician support facilitator at the ‘Imiloa Astronomy Center of ­Hawaii, a center for informal science education at the University of Hawaii at Hilo showcasing astronomy and Hawaiian culture as parallel journeys of human exploration.