(This story was updated with a cloud cover forecast on Sunday morning, Jan. 20.)
On Sunday night, the air will be cold and skies clear for parts of the country as a total lunar eclipse bathes the moon in an eerie blood-red hue. From Hawaii to Maine, all 50 states will have a chance to see it, weather permitting — the most widely visible lunar eclipse in the United States since October 2014.
Oh, and it will be a supermoon, meaning it will be ever so slightly closer to Earth than normal.
The cloud-cover forecast suggests the eastern half of the United States will have the best viewing conditions — with fairly widespread clear skies in the wake of a big storm exiting New England. Bundle up, as many areas will experience frigid temperatures and subzero wind chills.
Out west, pervasive cloud cover will make seeing the eclipse more challenging.
Lunar eclipses occur when Earth passes directly between the sun and the moon, forming a straight line. This year, the moon will be high in the sky, which makes this the best chance to watch an eclipse in years.
Specific starting and ending times of the eclipse will vary based on time zone.
|Time zone →||Eastern||Central||Mountain||West||Alaska||Hawaii|
|Total eclipse begins||11:41 p.m.||10:41 p.m.||9:41 p.m.||8:41 p.m.||7:41 p.m.||6:41 p.m.|
|Totality||12:13 a.m.||11:13 p.m.||10:13 p.m.||9:13 p.m.||8:13 p.m.||7:13 p.m.|
|Total eclipse ends||12:43 a.m.||11:43 p.m.||10:43 p.m.||9:43 p.m.||8:43 p.m.||7:43 p.m.|
During totality, no sunlight reaches the moon, because Earth blocks all the rays. The only reason the moon is visible is because some of the light is refracted, or bent, around the edges of the globe and toward the moon. The reddening of the moon is akin to what makes sunsets so spectacular, with pink and orange hues. Green and blue don’t make it through, scattered away by the particles in Earth’s atmosphere. The only light wavelength left is red — dimly illuminating the moon with less than one-thousandth of the full moon’s normal brightness.
It’s difficult to predict the exact hue of lunar eclipses, but whatever shade results can offer insight about the chemistry of Earth’s atmosphere. Maroon or auburn tinges have been known to result when the atmosphere is particularly polluted, often after large volcanic eruptions. Particles in the atmosphere generate more clouds, boosting the number of small water droplets in the air, and the tiny drops of water in clouds scatter light very well.
In addition to changing color, the moon will be super. (Not that it isn’t super already — we love our only natural satellite.) This recently popular but decades-old term is used to describe a full or new moon that is closest to Earth in its orbit, which is elliptical, just like Earth’s orbit around the sun. You probably won’t be able to notice the difference in the size or brightness of the moon, but it is noteworthy enough as an astronomical event. The next extreme supermoon, when the moon is as close to Earth as it can be, will be Jan. 21, 2023.