An intriguing lunar phenomenon known as a Wolf Moon Eclipse will grace the night sky on Jan. 10, 2020. The January full moon will drift into Earth’s shadow, inaugurating the first of 13 full moon appearances in the year to come.
During the first full moon of the new decade, the Moon will only enter Earth’s faint outer shadow, or “penumbra,” and will not be engulfed completely. This spectacle, otherwise known as a “penumbral lunar eclipse,” means that the full moon will only diminish in brightness rather than being entirely shrouded by the shadow of the Earth, as in a total lunar eclipse.
According to Time and Date, there are two conditions necessary for a penumbral lunar eclipse. The Moon must be in its fullest expression, and the Sun, Earth, and Moon must be imperfectly—almost but not completely—aligned.
Many astronomy aficionados are excited about the Jan. 10 event given that only about one in three of all lunar eclipses are penumbral.
It will be a lunar spectacle with a limited guest list, however. Only stargazers residing on the night-side of the Earth at 7:10 p.m. Universal Time (UTC+0), as per Forbes, will be able to witness the full illumination of the penumbral lunar eclipse. This timezone includes parts of Australia, Europe, Africa, and Asia.
According to EarthSky, while a full moon may appear “full” to the naked eye for several days, astronomers regard the Moon as being truly “full” during a specific instant only, as defined by the Moon’s placement at 180-degree opposition to the Sun in ecliptic longitude.
The January full moon will reach its fullest expression at 7:21 p.m. Universal Time on Jan. 10, just 11 minutes after peak illumination of the penumbral lunar eclipse.
Because the eclipse will occur during daylight hours Eastern Time, it will not be visible from most of the Americas. While the sight of January’s Wolf Moon rising in the east will nonetheless be a beautiful sight in its own right, people residing in the Americas will have to wait patiently for the “Thunder Moon Eclipse” of July 5, 2020, for the full show.
The January full moon has long been called the Wolf Moon in North America, owing to the naming of the full moons with reference to the seasons by Native American groups and Colonial Americans, as per The Old Farmer’s Almanac. The Wolf Moon was so called because wolves were thought to howl in hunger throughout the cold, scarce month of January.
Other nicknames for the January full moon include the Ice Moon, the Old Moon, and the Moon After Yule, since this full moon is the first to occur after the holiday season.
The year 2020 boasts a grand total of four penumbral lunar eclipses, with January’s Wolf Moon Eclipse being hailed by the experts as the deepest of them all. The remaining penumbral lunar eclipses will occur on June 5, July 5, and Nov. 29.
In the northern hemisphere, January’s night skies are widely revered by astronomers as the darkest and clearest of the year. The first lunar eclipse of the year couldn’t have chosen a more appropriate time to appear.