A total lunar eclipse is coming next month. A lunar eclipse happens when the Earth passes directly between the sun and the moon, casting a giant shadow on the lunar surface. The moon will appear red, as it's lit by sunlight filtered through the Earth's atmosphere. The eclipse happens next Tuesday morning at 6:04 to 7:02 a.m. EST but unfortunately, the moon will set during totality in the Eastern time zone. Other U.S. time zones will see the totality.