Skywatch: Traditional star compass assists navigators at sea

Once again we return to the first of our four star families, Kekaomakali‘i (the Bailer of Makali‘i), as it makes its nightly east-to-west progression from horizon to horizon.

A short review of what we covered 12 months ago might be useful if you are new to the Skywatch column. The star map that we feature is presented upside down and is intended to be held above your head facing south for proper orientation.

We explain direction through an Indigenous device called a star compass, which is used to orient the user or a vessel within the circle of the horizon.

The circle of the horizon is divided into 32 points defined as houses. Each house is identified by the siderial or celestial body that resides there — sun, moon, planets and stars. There are two horizons on our star compass: Hikina, or east, meaning “to arrive,” and Komo­hana, or west, meaning “to enter.”

If you stand with your back toward Hikina, you face Komohana. If you raise your right hand so that it extends 90 degrees from your body, it points toward ‘Akau, which means right or north; raise your left hand and it points to Hema, left or south.

Stars rise in parallel tracks and move from the arriving horizon, Hikina, to the entering horizon, Komohana. Fifteen of the 32 houses form the Hikina side of the star compass, and another 15 form the Komohana side.

The remaining houses, ‘Akau and Hema, are the pivot points that divide the arriving and entering horizons. Once a siderial body enters the circle of the horizon, it will climb skyward until it arrives at the meridian, the highest point on its westward track formed by an imaginary line that runs between ‘Akau and Hema, the north and south celestial poles. As it crosses the meridian it begins its descent toward the entering horizon, Komohana, and disappears.

Siderial bodies are hemispherical: If they rise in the Northern Hemisphere, they set in the Northern Hemisphere, if they rise in the Southern Hemisphere, they set in the Southern Hemisphere. A star rising in Hi­kina will set in Komohana.

‘Akau is marked by the star Hokupa‘a (Polaris).

Kekaomakali‘i forms the shape of a canoe bailer, carrying a series of bright constellations within the scoop. Starting in the direction we call Manu Ko‘olau, or northeast, the scoop is formed by Hokulei (Capella); Nanamua and Nanahope (the twins of Gemini, Castor and Pollux); Puana (Little Dog); and ‘A‘a (Sirius), the brightest star in the night sky.

The handle of the bailer is formed by drawing a line southward between ‘A‘a and Keali‘iokonaikalewa (Canopus), the second-brightest star in the night sky. The bailer carries within its celestial interior Kaheiheio­nakeiki (Orion’s Belt); Kapuahi (Aldebaran in Taurus the Bull); and Makali‘i (the Pleiades), the celestial marker for the annual Makahiki season here in Hawaii.

The star compass is an effective device for orientation and navigation at sea because Hawaii and most of the islands of the South Pacific inhabit a region that spans the tropics, which lie between 23.5 degrees north and 23.5 degrees south. Within this region the rising angle is vertical at the equator, tilted slightly southward in Hawaii and tilted slightly northward in Tahiti, making the use of siderial bodies effective bearing markers along the visual horizon.

Featured Mauna Kea discovery/observation

A team of astronomers working with data from the Subaru Telescope on Mauna Kea is studying the evolution of great galaxies in the Coma cluster. The astronomers are interested in the tails of the galaxies that stretch across the cluster. These tails will tell the stories of intergalactic collisions and explain the history of how the galaxy came to be.

Understanding the evolution of these young galaxies is an important aspect of modeling the continuing evolution of the whole universe. Learn more about this continued research into the history of galaxies by visiting subarutelescope.org/en/results/2021/12/05/3012.html.

Evening observations

While Jupiter and Saturn have been brilliant in the early evening sky for the past several months, January will be the last month that we will be able to see these two large gas giants in the night sky.

The faint planet Saturn sets just before 8 p.m. for most of the month; however, careful stargazers will be able to catch the faint planet during dusk, from 5:30 to 7.

The bright planet Jupiter will be low in the southwestern sky; as the fourth-brightest object in the sky, it will stand out during the early evening hours. Using a good pair of binoculars to spot Jupiter low on the horizon, you might be able to make out some of the planet’s largest moons.

In the northwestern sky we find the “W” shape of ‘Iwakeali‘i, the royal frigate bird. About 15 degrees south of the bird’s western wing, careful observers will find a small, faint, fuzzy object in the sky.

This object is the Andromeda Galaxy, the closest full-size galaxy to the Milky Way and the only object visible to the naked eye that is outside of Earth’s own galaxy. Andromeda is approximately 2.5 million light-years away from Earth.

Beneath the famous three stars that cut across Kaheiheionakeiki, you will be able to make out a small faint smudge in the sky. Through a good pair of binoculars or a telescope, you will see the dynamic Orion Nebula (M42), one of the most famous stellar nurseries in the sky.

Within this gas and dust cloud, young stars are being formed. Astronomers on Mauna Kea have also been able to discover protoplanetary disks within the nebula and have borne witness to the birth of new solar systems.

Morning observations

Throughout January, dawn will begin to color the sky around 6 a.m., and the sun will rise around 7:10.

The early morning sky looks very different from the evening sky, and morning observers will get a unique view.

At the start of January, Mars will rise around 5 a.m. and will stand out in the eastern sky with its distinctive red color.

At about 6 a.m., if you face south, with a nice flat southern horizon, you will be able to catch the notable shape of Hanaiakamalama (the Southern Cross), standing upright. Next to this will be the two pointer stars Kamailemua (Beta Centauri) and Kamailehope (Alpha Centauri).

Kamailehope, the more easterly of the two pointers, is the closest star system to our solar system at only four light-years away. While Kamailemua appears to have a similar level of brightness to its other pointer, it is much farther at almost 400 light-years away.

The brightness of these pointer stars appears so similar because Kamailehope is fainter but closer, and Kamailemua is very bright star and farther away.

January 2022 Skywatch by Honolulu Star-Advertiser

The ‘Imiloa Astronomy Center of Hawaii is a center for informal science education at the University of Hawaii at Hilo showcasing astronomy and Hawaiian culture as parallel journeys of human exploration.