'You just need your eyes' for eclipse: What to expect from Sunday's super flower blood moon

Skywatchers will be turn their attention to the moon Sunday to catch a total lunar eclipse likely to be seen across most of eastern North America - weather permitting, of course.

If conditions are right, the "super flower blood moon" could prove a striking sight.

A total lunar eclipse occurs when a full moon enters the Earth's shadow. According to the Adler Planetarium in Chicago, a total lunar eclipse has not been seen in the Chicago area since January 2019.

The partial eclipse is set to begin around 9:27 p.m., with the totality of the moon within Earth's shadow from 10:29 to 11:53 p.m.

Since May is known for springtime blossoms, the full moon for this month has been traditionally dubbed by astronomers as the "flower moon." And a "super moon" occurs due to the varying circular orbit of our closest celestial satellite, which means the moon appears bigger in the sky because it is closer to Earth.

Aside from the weather, another uncertain aspect of Sunday's lunar eclipse is how colorful the resulting "blood moon" will be.

"The color isn't necessarily going to be red," said Michelle Nichols, director of public observing at the Adler Planetarium. "We don't know what color we're going to get until it happens."

Nichols is quick to point out that "blood moon" isn't an official astronomical term. The lore is that decades ago a preacher prone to apocalyptic predictions coined the term "blood moon" in association with lunar eclipses.

"People started co-opting that term 'blood moon' because they thought, 'Wow, the moon does look red like blood,'" Nichols said.

The moon's reddish appearance during an eclipse occurs because at the time it achieves totality in shadow, sunlight still shines through the atmosphere at the outer edges of the Earth. Just like when the sun's light passes through the sky at sunset or sunrise, the blue colors from the visual spectrum get scattered by Earth's air, leaving the red and orange hues.

Nichols likens a lunar eclipse to showing people the color of the collective sunrises and sunsets around the entire planet at that exact moment.

"It can depend upon how clear that air is at that moment, how cloudy it is, or if there's been volcanic activity," said Nichols, adding that the blood moon's appearance could be affected by the eruption in January of the underwater volcano in the Pacific Ocean near Tonga, which spewed massive amounts of ash and gas into the atmosphere.

"That might be what affects the color," Nichols said. "Or it might not."

On Sunday, Nichols will be surrounded by hundreds of skywatchers on the Adler Planetarium grounds for a lunar eclipse gathering, though the limit of 800 free tickets has nearly been reached. Suburban skywatchers who want to congregate closer to home can join the Lake County Astronomical Society outside the Volo Bog Visitor's Center in Ingleside.

But Nichols stresses that any location where the moon is visible is ideal for viewing a lunar eclipse.

"No telescopes or binoculars required, but we will have some available if folks want to check them out," Nichols said. "The great part about the moon is you just need your eyes."

Lunar eclipse gatherings

Location: Adler Planetarium, 1300 S. DuSable Lake Shore Drive, Chicago, (312) 922-7827, <a href="https://www.adlerplanetarium.org/event/total-lunar-eclipse-observing-event">adlerplanetarium.org</a>

Admission: Free, but advance ticketing limited to 800 people

Event time: 9 p.m. to midnight Sunday, weather permitting

Location: Lake County Astronomical Society at Volo Bog Visitor Center, 28478 W. Brandenburg Road, Ingleside, (815) 344-1294, <a href="https://www.lcas-astronomy.org/calendar/event_details.php?calId=190">lcas-astronomy.org</a>

Admission: Free

Event time: 8:30 to 11:30 p.m. Sunday, weather permitting