For the third time in a two-year timespan, a "blood moon" will cast an eerie glow above Earth this weekend.
The total lunar eclipse, which is set for the early morning hours of Saturday, April 4, is the third in a "lunar tetrad," or four successive lunar eclipses with no partial lunar eclipses in between, according to Eric Edelman, the host of Slooh's live broadcast of the event beginning Saturday at 6 a.m. EDT.
Slooh frequently airs live astronomy events by using community observatories from all around the world. For those unable view the total eclipse, you can watch the eclipse unfold live below. After the event concludes, Slooh will show a replay of the event.
According to Edelman, this eclipse will be a "Pacific Ocean Spectacle" and it will be best seen from Eastern Australia, Japan, Hawaii, Northeastern Russia and western Alaska.
"The farther west you are in the U.S., the more you will be able to see," Edelman said.
For observers in California, the conditions should be "pretty good," with the only issues being the potential for low clouds to develop along the central coast and in Southern California, AccuWeather.com Senior Meterologist Ken Clark said. Viewers in Arizona could potentially have some high clouds that that may dull the eclipse, he added.
In the Pacific Northwest, west of the Cascade Mountain Range, there will also be some spotty raindrops to dodge and overall conditions will be touch-and-go to catch a good view, according to AccuWeather.com Meteorologist Dave Houk. East of the Cascades in Washington, generally partly cloudy skies will offer a better opportunity for viewing, he said.
The moon will first begin passing through the outermost portion of the Earth's shadow (what's known as the penumbral stage) at 5:01 a.m. EDT, and viewers will notice a subtle dimming. It is when the Moon gets to the dark, inner (umbral) shadow that stargazers will see a distinctive darkness spread across the moon around 6:15 a.m. EDT.
This total eclipse will be known for its brevity, as the blood moon portion will last a little less than five minutes, making this the shortest total eclipse this century, Edelman said. From 7:58 a.m. EDT to 8:02 a.m. EDT is when those who crave celestial sightings will want to look to the sky to view the red moon.
"Totality" is when the Moon is fully inside Earth's shadow. Some total eclipses last for more than an hour but the reason for the abbreviated totality period is a result of the fact that the moon is skimming the outskirts of Earth's shadow rather than passing centrally through it, according to NASA.
The reason those in the East won't be able to glimpse the full total eclipse is due to moonset.
"In New York City, the moon will be below the horizon at 6:36 a.m. although the partial eclipse from that location would actually end at 9:44 a.m. They only get to see the beginning of the eclipse," Edelman said.
Those in the Eastern U.S. will likely not have the best viewing conditions anyway due to clouds, but especially in New England, which will be facing stormy weather, AccuWeather.com Meteorologist Mark Paquette said. Elsewhere, Paquette said conditions look average in the mid-Atlantic and the Ohio and Tennessee valleys, with good viewing weather for Florida, the Mississippi Valley and western Great Lakes.
The blood moon moniker is derived from the red color that is cast over the moon from light refracting in Earth's atmosphere.
"The red portion of sunlight is what makes it through our atmosphere to the other side, bent toward the eclipsed Moon, so that even though the Moon is within Earth's shadow, the red portion of the Sun's light can give the Moon this ghostly illumination," Edelman said, adding that how red an eclipsed Moon gets depends on the characteristics of the atmosphere on that day such as clouds, and temperature.
This is the second of nine lunar tetrads in the 21st century, with the third scheduled to begin in April 2032, Edelman said. The fourth and final lunar eclipse in this tetrad is set for Sept. 28, 2015.