July 2018 is set to be an extremely exciting month for stargazers and backyard astronomers from all walks of life as the world bears witness to the longest total lunar eclipse of the 21st century, according to The Express. The total lunar eclipse will also feature a “blood moon” phenomena as a result of sunlight being scattered throughout the Earth’s atmosphere, making it a doubly delightful treat for those who manage to get a glimpse of the night sky.
Taking place over the course of nearly two hours – official estimates placing the entire elapsed time of the eclipse and blood moon at 1 hour, 43 minutes – the July 2018 total lunar eclipse outstrips the Super Blue Blood Moon combination that occurred in January of this year by nearly three-quarters of an hour.
According to astronomer Bruce McClure of EarthSky.org, the eclipse will reach its peak sometime around 8:22 p.m. UTC or Coordinated Universal Time. This translates to roughly 4:22 p.m. EDT or Eastern Daylight Time. Unfortunately, most residents of North America will have to settle for a high-definition video of the eclipse as it occurs, while those in the European Union and neighboring areas may have a bit more luck to view the extremely rare astronomical event with the naked eye.
The space expert relayed some relevant facts surrounding the upcoming total lunar eclipse and blood moon combo.
“The July 2018 full moon presents the longest total lunar eclipse of the 21st century on the night of July 27-28, 2018, lasting for a whopping one hour and 43 minutes… A partial eclipse precedes and follows the century’s longest total lunar eclipse, each time lasting one hour and six minutes… So, from start to finish, the moon takes nearly four hours to cross the Earth’s dark umbral shadow.”
When the eclipse does take place, the Moon will pass through the shadow cast by Earth, and will then adopt a mantle of deep ruby red to burnt orange instead of completely disappearing from sight. This unusual aesthetic occurrence is due to what is known as Rayleigh scattering – the scattering of light particles in any given medium, without any sizable change in wavelength – and in this case, a filtering of bands containing green and violet light in the atmosphere. This lends the eclipse in July the characteristic reddish hue that denotes a blood moon.
Rayleigh scattering is a scientific phenomenon that is also responsible for the color of Earth’s sky and our beautifully dusky sunsets. A close scientific cognate of Rayleigh scattering, the Tyndall effect which refers to the scattering of light through a colloidal substance, is how we perceive blue and green colored eyes. In fact, blue and green pigments are never present in the human iris, we perceive them in this color due to light scattering effects such as the Rayleigh and Tyndall variants.
The total lunar eclipse will be bracketed on both sides by partial lunar eclipses, beginning at 6:24 UTC and ending at 10:29 UTC, or 2:24 p.m. EST and 6:29 p.m. EST respectively.
The lunar eclipse will be much longer this time because the full moon and the lunar apogee both coincide on the same date in July 27th of this year, McClure says.
“Sometimes called an apogean full moon, or micro-moon or mini-moon, this smaller and slower-moving full moon takes more time to cross the Earth’s shadow than does a full moon that’s closer to Earth and moving faster in orbit. That’s why a full moon at or near lunar apogee adds to the duration of a total lunar eclipse. The longest possible total lunar eclipse is one hour and 47 minutes.”
The lunar apogee represents a period of time in which the Moon is at it’s farthest orbital point away from Earth, making it appear smaller, more distant. The coincidental factors contributing to this alignment of the celestial bodies for maximum visual effect will not take place again during our lifetimes, making it a must-see event.