Sunday’s Super Blood Wolf Moon Eclipse Explained, and Venus Kisses Jupiter in the Morning!
The Super Blood Wolf Moon (Total Lunar Eclipse)
You’ve probably seen references to Sunday’s lunar eclipse as a Super Blood Wolf Moon, or a permutation of those words. These dramatic terms might elicit chuckles and/or eye rolls from astronomers, but they serve a purpose — to capture the imagination of the public and get them to head outside and look up! There are valid reasons for using each part of that label. Let’s break that down.
Blood Moon — The Earth is a solid sphere. The sunlight shining on Earth casts a circular shadow into space opposite from the sun. When an object, such as the International Space Station or the moon, passes through that shadow, no direct sunlight can reach it, so the object darkens. Some of the sunlight streaming closely past Earth passes through our atmosphere. The air refracts (or bends) the rays of sunlight because it slows the light down a little, and that refraction allows a small percentage of the sunlight, bent around the Earth’s perimeter, to reach the moon and slightly illuminate it. If Earth had no atmosphere, the moon would turn completely dark during a lunar eclipse!
During totality, only red light reaches the moon because our atmosphere scatters some wavelengths of light more than others. White sunlight is composed of a rainbow of component colours. The sky is blue in daytime because the molecules in the air scatter shorter wavelength blue light and lets longer wavelength red light pass straight through. Try this experiment. Shine a flashlight through a glass of water placed near the wall in a darkened room. You’ll see a distorted beam of white light on the wall. Now put a few drops of milk in the glass and the entire liquid will glow with a bluish light! If you didn’t add too much milk, you might also see that light on the wall is a now a warmer colour because the cool, blue wavelengths have been scattered throughout the liquid rather than passing through. The same effect causes sunsets to turn red, and only that reddened light can reach the moon during totality — colouring the moon a rusty red, or blood, colour.
Wolf Moon — The moon has always shone down upon humans on Earth. Eventually, people began to seek to understand our natural environment and to take advantage of the annual variations in the seasons to schedule planting, harvesting, hunting, and to celebrate life events. The twelve (sometimes thirteen) full moons per year acted as obvious celestial markers. Full moonlight allowed people to be out at night; hunting, or working the fields for extra hours to get the harvest in.
Each society around the world has its own set of stories for the moon and every month’s full moon has one or more nick-names. The Wolf Moon term is likely derived from North American First Nations traditions, although some think it has an Anglo-Saxon origin. In either case, it’s likely that hungry wolves were calling to one another in the dead of winter, and left an impression on people before our modern era. The January full moon, eclipsed or not, is known as the Wolf Moon, Old Moon, or Moon after Yule. It always shines in or near the stars of Gemini (the Twins) or Cancer (the Crab).
Super Moon — The moon orbits Earth every 27.3 days. The shape of the orbit is an ellipse that brings the moon alternatively closer and farther from the Earth. The difference in distance between perigee, the point in the moon’s orbit when it is closest to Earth, and apogee, when the moon is farthest away, is about 50,000 km. That causes a perigee moon to appear about 14% larger than an apogee moon — about the difference between a Canadian $1 and $2 coin when held at arm’s length. It’s not that much — visually. The closer moon will also be slightly brighter.
The term supermoon was coined to describe a full moon that happens while the moon is at or near perigee. January’s eclipsed full moon will occur fifteen hours before perigee, making it appear about 7% larger than average and generating high tides globally.
The supermoon aspect of this eclipse actually works against us. When the moon is near perigee, it is moving faster in its orbit, so it will cross the Earth’s shadow in a shorter time. The closer moon is also larger, so it remains fully eclipsed for a shorter time.
Total Lunar Eclipse Visibility and Timings — This lunar eclipse will be visible start to finish in North and South America, the eastern Pacific Ocean, and westernmost Europe. Much of the eclipse will be seen in central and eastern Europe, but observers there will miss the later stages of the eclipse because they occur after moonset. For the western Pacific region, the moon will rise after the eclipse begins.
The partial phase, when the edge of the moon begins to darken, will begin when the moon contacts the Earth’s umbra at 10:34 pm EST on Sunday evening in North America (or 7:34 pm Pacific time and 03:34 UT). Starting at that time, look for the darkness to creep over the moon, growing from along its lower left edge.
At 11:41 pm Eastern time (8:41 pm PST), the last strip of brightly lit moon will vanish as the moon finally entirely enters the Earth’s umbra. The darkened and a coppery red appearance won’t be obvious visually or in photos until the moon is well into the shadow. The moon will stay fully within the shadow (referred to as totality) for 62 minutes. It will pass deeply through the shadow, and the moon’s southern half will appear darker than its northern half.
Greatest, deepest eclipse will occur at 12:13 am EST. After this, most people will head to bed because the second half of the eclipse mirrors the first half. The total eclipse phase will end when the moon begins to leave the umbra at 12:43 am Eastern Time on Sunday. At that time, look for a growing strip of illuminated moon to appear along the moon’s lower left edge. The partial phase of the eclipse will end at 1:51 am Eastern Time.
Now you know what to look for, and when to look. If you have a telescope, of any size, hold your phone’s camera over the eyepiece and take some photographs, or prop up your tablet or phone somewhere and take a time lapse movie of the eclipse. Hopefully the skies will be clear wherever you are! Don’t let cold weather keep you indoors for this one. The next total lunar eclipse won’t occur for the GTA until May, 2022.
The Moon and Planets
After Sunday night’s total lunar eclipse, the moon will spend the week waning and rising later. On Tuesday night, the moon will pass only two finger widths to the left of the bright, white star Regulus in Leo (the Lion). After mid-week, you can look for the moon in the western morning sky on your way to school or work.
Next Sunday afternoon, the moon will reach its Last Quarter phase, when it will rise at midnight and appear half-illuminated — on its western side. (Directions on the moon are opposite to sky directions.)
This week, Mars will shine as a medium-bright, reddish pinpoint of light in the southwestern sky. It will set at about 11:30 pm local time. Mars is slowly shrinking in size and brightness as we increase our distance from it.
Blue-green Uranus is about 1.5 finger widths above, and slightly to the left of the modestly bright star Torcular (or Omega Piscium). This week, Uranus will be at its highest point, over the southern horizon, at about 6:30 pm local time — the best position for seeing it clearly. Dim, blue Neptune will set shortly after 9 pm local time, so look at it before 8 pm, while it’s higher. Neptune is sitting about two finger widths to the upper left of the modestly bright star Hydor (Lambda Aquarii). Hydor, and a pair of stars to its east (upper left), form a sideways narrow triangle with Neptune inside of it.
Both Saturn and Mercury are too close to the sun to be seen this week, but next week Saturn will join the other two bright morning planets, Jupiter and Venus. Spectacularly bright Venus is now swinging back towards the sun, while not-as-bright Jupiter is being carried the other direction — west and higher. The two planets “kiss” this week. On Tuesday morning, Jupiter will be positioned only 2.5 finger widths south (to the lower right) of Venus. They will both fit within the field of view of binoculars. Look for the bright, reddish star Antares, the “rival of Mars” sitting a palm’s width to the right of Jupiter.
Astronomy Skylights for the week of January 20th, 2019 by Chris Vaughan.
Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!