The twin stars in the bucket of the Little Dipper, Holopuni (Kochab) and Hokumau (Pherkad), are good clues for determining latitude in the Southern Hemisphere.

When Holopuni and Hokumau make their nightly east-to-west journey across the night sky, they will travel across the celestial meridian, an imaginary line that runs from the celestial north pole through to the celestial south pole. At the equator, when crossing the meridian, they attain an altitude of 16 degrees (Holopuni) and 18 degrees (Hokumau) in height above the northern point on the horizon.

As you sail south from the equator, Holopuni and Hokumau will get closer and closer to the horizon, losing a degree of altitude for every 60 nautical miles you travel south. When Holopuni and Hokumau are no longer visible because they have faded into the northern horizon and are being obscured by the clouds, you should be approaching the Tuamotu Archipelago, a ban of 78 low-lying coral atolls.

These atolls form a screen of islands that stretch about 500 miles from east to west. The best strategy to arrive in the Tuamotu Archipelago is to leave from the easternmost point of the Hawaiian Islands, Hilo. Pointing the canoe’s bow close to the direction of Manu Malanai, southeast on the Hawaiian star compass, keep the canoe on a windward heading until you make landfall.

FALL IN THE Northern Hemisphere began Wednesday, when the sun crossed the equator in a biannual event, the equinox. This also heralded the Southern Hemisphere’s spring season. Equinox comes from the Latin word meaning “equal nights,” reflecting the fact that when the sun is directly above the equator, day and night are equal in length. In March the equinox will occur again when the sun crosses the equator on its northward journey and brings on the Northern Hemisphere’s spring.

Kalupeakawelo, the Kite of Kawelo, is our fall star family, the last of the four star families for 2021. Kawelo was a Kauai chief and cultural hero of the Hawaiian people, most notable for the many athletic competitions in which he excelled.

The stars that comprise the constellations and asterisms of this star family generally run in a north-to-south direction across the star field.

The northern section of this starline begins with ‘Iwakeli‘i (Cassiopeia, the Greek queen of Aethiopia). This celestial constellation resembles a “W” and is associated with Cepheus, Kamo‘i, to the north and Andromeda to the south.

Cepheus was Cassiopeia’s husband; Andromeda was their princess daughter. Legend has it that Cassiopeia was exiled to the night sky after angering Poseidon with a boast that Andromeda was more beautiful than the Nereids, or sea nymphs; Andromeda was later rescued by the Greek hero Perseus.

ANDROMEDA is represented by the star Alpheratz, one of the four stars that make up the boxlike “lupe” (kite) at the heart of the star family, which is also known as the Great Square of Pegasus. Pegasus is the magical winged horse born when Perseus cuts off the head of Medusa.

The Great Square of Pegasus consists of three stars from Pegasus and one star from Andromeda arranged to form a celestial square. One side of the square is made up of Kakuhihewa (Scheat) in the north and Keawe (Markab) in the south, followed by Manokalanipo (Alpheratz) in the north and Pi‘ilani (Algenib) in the south.

Scheat-Markab and Alpheratz-Algenib are also meridian pointers, meaning they move together across the celestial meridian, that imaginary line that runs overhead from celestial north to celestial south and points to the celestial north pole.

This is an important constellation that oceanic wayfinders use to identify the celestial north pole. Running to the south of this starline through Scheat and Markab are the stars Fomalhaut, Beta Grus and Alnair; and from Alpheratz and Algenib are the stars Diphda, Ankaa and Achernar. These stars form the guide strings that control Kawelo’s kite as it soars overhead between the eastern and western horizons.

Special events

The shooting stars of the Orionid meteor shower will decorate our sky throughout October. These meteors typically show up from east to west and will appear to come from the rough direction of the constellation Orion, which will rise in the east around 11 p.m.

The shooting stars of this meteor shower are leftover debris from the tail of Halley’s Comet, which passed through the inner solar system in 1986. When the debris encounters our atmosphere, it burns up as it falls to Earth, creating the shooting stars.

The peak of the Orionids will occur Oct. 21 around 1:30 a.m.; shower-watchers can expect a shooting star about every three minutes. The full moon a day earlier, on Oct. 20, will likely obscure some of the fainter shooting stars, but the meteor shower will still be visible during its run from Oct. 2 to Nov. 7.

Evening observations

Stargazers watching the early evening sky will continue to see three notable planets.

The brightest planet, Venus, can be seen near the western horizon immediately following sunset and will stand out during dusk and into the early evening. As October progresses, Venus will pass incredibly close to the bright red giant star Lehuakona (Antares) from Oct. 14-17. Lehuakona is the brightest star that appears in Maui’s fishhook.

We will get the best view of Venus on Oct. 29 when the planet will appear to be at its fullest position from the sun, known as its greatest eastern elongation as the planet is at its easternmost position from the sun. On this night, Venus won’t set until 8:46 p.m.

Venus is not only the brightest object in the sky at this time; it is also the hottest planet in the solar system. Due to its proximity to the sun, all water on the planet’s surface boiled up into its atmosphere where it mixed with the sulfuric gases and carbon dioxide coming from the planet’s volcanoes, building up a thick layer of clouds which cover the planet.

These clouds create a runaway greenhouse effect that causes the planet to get ever hotter, making it the hottest planet in the solar system.

Astronomers using the James Clerk Maxwell Telescope on Mauna Kea are able to study the molecular components of Venus’ atmosphere; last year researchers using the JCMT detected the unique compound phosphine in Venus’ thick clouds.

As Venus prepares to set in the western sky, Jupiter and Saturn can be seen high above the direction of south. They are the two largest gas giant planets and are primarily made of hydrogen and helium gases and liquids. Through a very good pair of binoculars or a telescope, you will be able to find Jupiter’s largest moons — Ganymede, Callisto, Europa and Io — as well as the famous rings of Saturn.

Morning observations

Throughout October, dawn will begin to color the sky around 5:10 a.m., and the sun will rise around 6:30 a.m. In these early morning hours, we will be able to observe the famous shape of Kaheiheionakeiki (Orion) high in the southern sky.

To the northwest of the recognizable shape of Kaheiheionakeiki, we will also see the famous star cluster of Makali‘i, also known as the Pleiades or the Seven Sisters. Toward Manu Malanai the incredibly bright star ‘A‘a (Sirius) will be highly noticeable in the sky as the sun rises. ‘A‘a is the brightest star that can be seen in the twilight sky.

As October marches on, Mercury will become increasingly visible on the eastern horizon during the early morning hours. Oct. 24 will be the best day to view Mercury as it will be at its greatest western elongation.

October 2021 Sky Chart 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.