Raven pins a table to the Sky Deck wall. "How often and how long. From NASA and OpenStax."
Rocket reads. "Totality in a solar eclipse never lasts more than about 7 minutes? That is nothing."
"What do you notice about the lunar row?" Raven asks.
"Up to 1 hour and 40 minutes," Rocket says. "And half of Earth can see it. Lunar eclipses are the generous ones."
Nova hovers over the table. "And the same spot on Earth?"
Rocket finds it. "A total solar eclipse about every 375 years." He whistles. "I should not wait for one."
Nova hums. "You do not have to wait. You have a lamp."
NASA's eclipse pages and OpenStax Astronomy give these numbers for how often eclipses happen and how long they last.
Read every row before you answer the questions. Remember that solar and lunar eclipses happen about equally often.
The difference is who gets to see them. A solar eclipse shadow is narrow; a lunar eclipse shows to half of Earth.
| Fact | Solar eclipse | Lunar eclipse |
|---|---|---|
| Moon phase | new Moon | full Moon |
| Whose shadow | the Moon's, on Earth | Earth's, on the Moon |
| Longest total phase | about 7 minutes at most | as long as 1 hour 40 minutes |
| Width of the shadow on the surface | about 480 kilometers wide | Earth's shadow could cover about four full Moons |
| Who can see the total phase | only people inside the narrow shadow path | everyone on the night side of Earth |
| How often, somewhere on Earth | a total one about every year and a half | a total one about once every two or three years |
| How often at one spot | a total one about every 375 years | whenever the Moon is up during one |
| All eclipses, both kinds | four to seven per year together | four to seven per year together |
During a total lunar eclipse the Moon often turns a dull coppery red. Sunlight bent through Earth's atmosphere still reaches it.
NASA says it is as if all the world's sunrises and sunsets are projected onto the Moon.
Thanks to our understanding of gravity and motion, eclipses can now be predicted centuries in advance.
| Statement | True or false? |
|---|---|
| Lunar eclipses can be seen from the whole night side of Earth. | ? |
| Solar eclipses happen far more often than lunar eclipses. | ? |
| Eclipses can be predicted centuries in advance. | ? |
| A total lunar eclipse at one spot is rarer than a total solar eclipse there. | ? |
Careful reading. Tomorrow you connect eclipses to everyday life, review the week and look ahead to the seasons.