January 2018 lunar eclipse


A total lunar eclipse occurred at the Moon’s ascending node of orbit on Wednesday, January 31, 2018, with an umbral magnitude of 1.3155. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon's shadow is smaller. Occurring about 1.4 days after perigee, the Moon's apparent diameter was larger.
Because the Moon was near its perigee on January 30, it may be described as a "supermoon", when the Moon's distance from the Earth is less than 360,000 km. The previous supermoon lunar eclipse was on September 28, 2015. The Moon was 360,202 km from the Earth. This eclipse also coincided with a blue moon, which occurs when there are two full moons in the same calendar month, or if there are four full moons in the same season. As this supermoon was also a blue moon, it was referred to as a "super blue blood moon"; "blood" refers to the typical red color of the Moon during a total lunar eclipse. This event was called a 'Trifecta'. This coincidence last occurred on December 30, 1982 for the Eastern Hemisphere, and otherwise before that on March 31, 1866. The next occurrence will be on January 31, 2037, one metonic cycle later.

Background

A lunar eclipse occurs when the Moon passes within Earth's umbra. As the eclipse begins, Earth's shadow first darkens the Moon slightly. Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color. The Moon appears to be reddish because of Rayleigh scattering and the refraction of that light by Earth's atmosphere into its umbra.
The following simulation shows the approximate appearance of the Moon passing through Earth's shadow. The northern portion of the Moon is closest to the center of the shadow, making it darkest and reddest in appearance.

"Super blue blood moon"

This was a "supermoon", as the Moon was near to its closest distance to earth in its elliptical orbit, making it 7% larger in apparent diameter or 14% larger in area, than an average full moon. The previous supermoon lunar eclipse was during the September 2015 lunar eclipse.
The full moon of January 31, 2018 was the second full moon that calendar month, making it, under one definition of the term, a "blue moon".
Additionally referencing the orange or red "blood" colors that occur during a lunar eclipse, media sources described the event as a "super blue blood Moon".

Characteristics

Visibility

The Pacific Ocean was turned toward the Moon at the time of the eclipse. Central and eastern Asia, Philippines, Indonesia, New Zealand and most of Australia got a good view of this moon show in the evening sky. For Western Asia, the Indian subcontinent, the Middle East and Eastern Europe, the eclipse was underway as the moon rose.
Along the U.S. West Coast, the total phase began at 4:51 a.m. PST. The further east, the closer the start of the partial phases coincided with moonset. Along the U.S. Atlantic Seaboard, for instance, the Moon had only just begun to enter the darkest part of Earth's shadow, the umbra, at 6:48 a.m. EST when it disappeared from view below the west-northwest horizon. The duration of the total phase was 77 minutes, with the Moon tracking through the southern part of the Earth's shadow. During totality, the Moon's lower limb appeared brighter than the dark upper limb.

Visibility map

Eclipse details

Shown below is a table displaying details about this particular lunar eclipse. It describes various parameters pertaining to this eclipse.
ParameterValue
Penumbral Magnitude2.29538
Umbral Magnitude1.31671
Gamma−0.30143
Sun Right Ascension20h56m18.8s
Sun Declination-17°17'47.0"
Sun Semi-Diameter16'14.0"
Sun Equatorial Horizontal Parallax08.9"
Moon Right Ascension08h56m05.0s
Moon Declination+16°59'44.2"
Moon Semi-Diameter16'35.2"
Moon Equatorial Horizontal Parallax1°00'52.6"
ΔT68.8 s

Eclipse season

This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.
January 31
Ascending node
February 15
Descending node
Total lunar eclipse
Lunar Saros 124		Partial solar eclipse
Solar Saros 150

Related eclipses

Eclipses in 2018

A total lunar eclipse on January 31.

Metonic

Tzolkinex

Half-Saros

Tritos

Lunar Saros 124

Inex

Triad

Half-Saros cycle

A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days. This lunar eclipse is related to two annular solar eclipses of Solar Saros 131.
January 26, 2009February 6, 2027