December 21 was the winter solstice, the shortest day of the year. Here in North Hawaii, sunrise on Dec. 21 was at 6:53 a.m. and sunset occurred at 5:49 p.m., giving us just around 11 hours of daylight. For friends and family on the mainland, the number of daylight hours is much shorter.
These changes in day and night happens because the Earth is not spinning perfectly vertical on its axis. Rather, the Earth is tilted at an angle of 23.5 degrees. During the winter, the northern hemisphere is tilted away from the sun. As a result, the sun is above the horizon for less time than in the summer.
Additionally, the light that does hit the Earth does so at a shallower angle. This shallow angle means the light is more diffuse or spread out. This weak light, visible for less time due to the angle of the Earth’s axis, is what gives us winter. The opposite, long-lasting, direct sunlight, is what gives us summer.
Now some of you might be saying, “I thought winter occurred because the Earth is farther from the sun!” This is a common misconception — the distance between the Earth and the sun has no bearing on the seasons. In fact, the Earth is closer to the sun during the northern hemisphere’s winter than in the summer.
These long winter nights bring some of the most famous constellations to our skies, including Orion, the Hunter. By Christmas, he will be visible in the east as soon as the sun sets. Look for the famous Belt of Orion, a line of three fairly bright stars, rising nearly vertically. To the north of the belt, in Orion’s shoulder, is the bright red star Betelgeuse. This star is a red supergiant; a star near the end of its life.
Preceding Orion in the sky is the beautiful star cluster of the Pleiades. This open star cluster can be found by lining up Betelgeuse with the star Aldebaran, the glowing red eye of Taurus the Bull. While Orion looks like a giant stick figure in the sky, Taurus looks like a large Y.
If you continue this line past Aldebaran, it will lead you to the Pleiades, seemingly sitting on the shoulder of the bull. This star cluster is well known around the world. In Hawaii it is called Makalii, a name which has been variously interpreted as “Little Eyes,” “Little Stars,” “High-Born Stars” and “Eyes of the Chief.” The Makalii are mentioned several times in the “Kumulipo,” the Hawaiian creation chant, included on the fifth line of very first verse.
This cluster is well known in Japan, where it is called Subaru. You may be familiar with this word for there is a successful automobile manufacturer with this name. This is why the logo of the company is a cluster of stars. The Subaru Telescope on Maunakea is also named for the star cluster.
From the staff of the Canada-France-Hawaii Telescope, we want to wish everyone a Merry Christmas and a Happy New Year!