What Is a Total Lunar Eclipse?
During a total lunar eclipse, Earth passes exactly between the full moon and the sun. As the celestial bodies move, the full moon enters Earth’s shadow until it is completely covered.
You may wonder, since the moon is constantly orbiting around the Earth, why there isn’t a lunar eclipse every month.
“It turns out the orbit of the moon is tilted relative to the orbit of the Earth around the sun so it doesn’t happen regularly,” says Andrew Fraknoi, Astronomy Department Chair at Foothill College. “Only when the two orbits cross—the orbit of the moon around the Earth and the orbit of the Earth around the sun—can you have an eclipse.”
For a visualization of what will be happening in space, check out this animated video from NASA, explaining the movements of celestial bodies during the total lunar eclipse on June 15, 2011.
- When to watch: The eclipse starts at 10:58 p.m. PST. At 12:07 a.m. the total eclipse phase begins. Earth will block the sun completely until 1:25 a.m., and then the moon travels through the semi-shadow until 2:33 a.m.
- Where to watch: Just go outside. You can see the eclipse from wherever you can usually see the moon.