UPI Almanac explores the rich tapestry of historical events that has marked and shaped our world. Each day’s analysis reveals noteworthy occurrences spanning a range of historical categories – notable people, cultural milestones, scientific advances and political happenings are just some examples – that represent history’s lasting relevance in our contemporary lives.
The Moon is waning
The Moon’s phases and cycle of waxing and waning remain an endlessly fascinating topic of study for many. While its four primary phases–New Moon, Full Moon, First Quarter, and Last Quarter–can easily be identified in the sky by their light emanating onto Earth, many other in-between phases may not be as evident in terms of light produced from their illumination.
Waxing refers to the process of increasing the portion of the Moon that illuminates at night after each New Moon; over several nights this phase sees more and more area become illuminated – expanding from just a sliver to nearly half moon in size within 7 days.
Waning occurs when the Moon begins to shed its brightness, as evidenced by its dimming crescent phase which occurs between full and last quarter moon phases in both hemispheres (in the former, it gradually reduces from right to left while, conversely, dimming may occur from left to right in both). In terms of illumination, in the Northern Hemisphere this means its illuminated area shrinks rightward as lunar months progress (whereas for Southern hemisphere moongazers it would dim from leftward).
The Sun is rising
The Sun does not rise and set in the same location every day; rather, its path revolves around Earth as it orbits it. That means you may witness different locations on your horizon witnessing sunrise and set times each day.
The direction in which the sun rises on any given day varies due to Earth’s tilt and rotation, the tilt and orbit of its Moon, and their annual cycle elliptic movement ellipticism; these variations are described by an analemma relationship.
Atmospheric refraction also accounts for why the Sun’s angle varies above the horizon, as light from its lower edge is refracted more than light from its upper edge, leading to it appearing narrower when low on the horizon and wider when higher up in the sky.
The Sun is setting
“The Sun rises in the east and sets in the west” is an oft-used phrase, yet this statement only holds true on equinox days (March 20 and September 22), when our sun directly overlies celestial equator.
At other times, however, the Sun will shift north or south from this position, leading to its noon altitude reaching its extreme northern or southern positions on the horizon.
At sunrise and sunset, the angle of the Sun’s rays depends on how much atmosphere is present; when passing through more air, they become scattered more easily, producing less dramatic lighting shows.
Different places experience sunrise and sunset at different times due to time zones; Caribou experienced sunset today at 4:43 p.m. while Seattle experienced it an hour later due to time zones – an estimated difference of 30 minutes!
The Moon is rising
The December moon, like all full moons, occurs roughly opposite to the sun and so rises higher in the sky than it does during summer months. If you trace a path with your finger to replicate what the sun would be doing on June solstice (or on its equivalent in Southern Hemisphere), its path would appear higher than it does during December.
Today marks a unique full Moon event as its fullness will occur near Castor and pollux of zodiacal constellation Gemini, visible as soon as tonight when it reaches its highest point in the night sky this week. Each night thereafter it will take less time for it to cross across the sky; this phenomenon known as the Waning Moon Effect can be observed worldwide but most visibly in mountainous regions, including Denver, Salt Lake City and San Francisco.
