Total lunar eclipse visible over Michigan on Sept. 26

ANN ARBOR—Michigan sky-watchers will have a beautiful view of a total eclipse of the harvest moon on Sept. 26, according to University of Michigan astronomer Richard Teske. The moon will be high in the east when the eclipse starts and the entire event will be visible to onlookers. An extra bonus is the presence of the ringed planet Saturn which will appear just below the eclipsed moon.

“Lunar eclipses occur when the sun, Earth and moon all line up with the moon hidden in the shadow cast behind the Earth,” Teske explained. During September’s eclipse, the moon— traveling at a speed of 2,300 miles per hour—will enter the Earth’s shadow starting at 9:12 p.m. By 10:54 p.m., the Earth’s round shadow will completely cover the moon. The moon will be fully illuminated again by 12:36 a.m.

“As the moon darkens, faint stars and constellations around it become visible,” Teske said. “Observers will see brilliant Saturn below the moon and a bit to its right. Careful watchers will notice the moon and Saturn changing their positions as the moon moves through Earth’s shadow.” Saturn’s brightness will not change, Teske added, because it is 880 million miles beyond the moon and unaffected by our planet’s shadow.

“We are usually unaware of the shadow because there is nothing in empty space for it to be cast upon,” Teske said. “If a huge movie screen were placed in space opposite the sun, we would see the screen brilliantly illuminated by sunlight with a dark circle—Earth’s shadow—about three times the moon’s width. The moon acts like a roving section of movie screen. It spends most of its time in bright sunlight, but sometimes orbits into the shadow’s darkness.”

Observers who go outside to enjoy September’s eclipse should watch for color changes on the moon as the phenomenon unfolds. The rim of Earth’s shadow usually has a reddish tint, an effect caused when sunlight grazing Earth’s edge passes through the atmosphere surrounding us. The air filters out all colors in sunlight, except reds. This is the same effect that makes the rising or setting sun appear to be red, according to Teske.

“During deepest totality the moon will probably be dimly visible and red-colored, because some sunlight traversing Earth’s atmosphere is refracted or ‘bent’ into the darkest parts of the shadow where it weakly illuminates the moon,” Teske said.

Lunar eclipses no longer have important scientific value and are not intensively observed by astronomers, according to Teske. “This is because the space age has transformed the moon from a distant astronomical body into a nearby, well-understood object. Spacecraft have crashed on it and landed there; others have circled it to photograph more than 99 percent of its surface. Astronauts have walked its surface and brought back over 800 pounds of moon rocks for study. There is almost nothing more to be learned by observations made from Earth.”

U-M News and Information ServicesUniversity of Michigan