By MICHELLE SCHMIDTBefore we knew the world was round, some people thought it was flat. But hundreds of years before they thought it was flat, we knew it was round.
Part of the reason the ancients knew the world was round is because of the regular astronomical event known as a lunar eclipse, which will occur at 3:30 a.m. Wednesday and is visible to the naked eye. For those who are interested, but not up for a wee-hour sky show, this weekend the Washington State University Planetarium is putting on presentations about the eclipse at times when viewers are more likely to be awake.
Lunar eclipses occur when the moon passes directly behind the Earth, into its shadow. While in the Earth’s shadow, the sun’s light doesn’t reflect off of it and the moon gets dark. It appears red at mid-eclipse of a total lunar eclipse.
“It’s strange to watch,” says Kaylan Petrie, a lifelong astronomy fan who is presenting the talk on eclipses at the planetarium.
“You’re looking at the moon and it starts to get dim and dark and there’s a curved shadow that appears on the face of the moon,” she explains. That curved shadow — made by the Earth — is one reason the ancients knew the Earth was round, she says.
Lunar eclipses take place a couple times a year; they occur at different times in the night but are not always visible from our location. Lunar eclipses don’t take place every full moon, she says, because its orbit is a little off kilter.
“The moon is really far away from the Earth,” Petrie says. “It’s farther than most people think it is and it doesn’t orbit in a perfect plane around the Earth.”
But Wednesday the moon and Earth do line up and those who want to watch it can set their alarms and do so. Petrie suggests getting out a bit before mid-eclipse so that you can watch the Earth’s shadow move across the face of the moon.
For those who prefer uninterrupted sleep, the moon will be visible long before 3:30 a.m. As a full moon close to the fall equinox, the moon is known as a “harvest moon” — a common, but not astronomical, term. That means the moon will rise right at sunset before it gets completely dark.
Not only will you see it while it’s still light, but the moon will be orange, like all moons that are rising up from the horizon. Guy Worthey, planetarium co-director and astronomy professor, explains the phenomena:
“There is a lot more air to look through when you are looking horizontally through the atmosphere, and this means that the air gets a chance to scatter light more.”
What’s left is light with a reddish tint, he says, which makes the moon appear orange — an event that is magnified when the moon is full.
Unlike stars, which are dimmer, the moon is easily viewed in the midst of city lights. For those who want a closer look at the moon but don’t have a telescope, Petrie suggests a good pair of binoculars. She’s seen planets and even a moon of Jupiter using them, and says the type of telescope Galileo used was about as good as the binoculars we have now.
If you go:
WHAT: Washington State University Planetarium Show: “Eclipses”
WHEN: 7 p.m. Friday and 5 p.m. Sunday
WHERE: WSU Planetarium
COST: $10/person, children 6 and younger are free. Cash or check only, unless purchased in advance at the Beasley Coliseum Box Office with no extra fee, or TicketsWest.com, (800) 325-SEAT with a convenience fee. Students are eligible for $7 tickets when purchased in advance.