Eclipses

What causes eclipses?

The Earth or Moon passes into the shadow of the other, blocking sunlight.

What are the two main types of eclipses?

Lunar Eclipse (Earth’s shadow on the Moon) and Solar Eclipse (Moon’s shadow on the Earth).

When can a lunar eclipse occur?

Only during a Full Moon, when the Moon is opposite the Sun.

When can a solar eclipse occur?

Only during a New Moon, when the Moon lies between Earth and the Sun.

Why don’t we see an eclipse every month?

The Moon’s orbit is tilted about 5° relative to Earth’s orbit (the ecliptic plane), so alignments rarely line up exactly.

What is the ecliptic plane?

The plane of Earth’s orbit around the Sun.

What are the two points where the Moon’s orbit crosses the ecliptic called?

The nodes.

What two conditions must align for an eclipse to occur?

(1) It must be Full or New Moon (2) The Moon must be near a node.

What is an eclipse season?

A roughly twice-yearly period when the Sun is near a node and eclipses can occur.

What are the three types of lunar eclipses?

Penumbral, Partial, and Total — depending on how much of the Moon enters Earth’s shadow.

Why does the Moon turn red during a total lunar eclipse?

Earth’s atmosphere bends and filters sunlight so red light reaches the Moon, creating the “Blood Moon.”

What are the three types of solar eclipses?

Total – Moon fully covers the Sun; Partial – only part covered; Annular – Moon too small to cover Sun completely.

What causes an annular eclipse instead of a total eclipse?

The Moon is at apogee (farther away), appearing smaller so a bright ring (“ring of fire”) remains.

During which eclipse does Earth’s shadow fall on the Moon?

Lunar Eclipse.

During which eclipse does the Moon’s shadow fall on the Earth?

Solar Eclipse.

Who can see a lunar eclipse?

Anyone on the night side of Earth – it’s visible to half the planet.

Who can see a solar eclipse?

Only people within the Moon’s shadow path – a narrow region on Earth’s surface.

What is the Saros cycle?

A repeating eclipse pattern lasting 18 years 11⅓ days; nearly identical eclipses repeat.

Why don’t Saros eclipses appear in the same place each cycle?

The extra ⅓ day shifts Earth’s rotation, changing the viewing location.

What was the “Great American Eclipse”?

The total solar eclipse of Aug 21 2017, visible coast-to-coast across the U.S.

When was the next major North American total eclipse?

April 8 2024 – visible across Mexico, U.S., and Canada.

How long can the longest total solar eclipse last?

Up to 7 minutes 30 seconds.

What is happening to the Moon over time?

It’s receding from Earth by ~3.8 cm per year.

What will the Moon’s movement cause in the distant future?

Total eclipses will disappear in ~500 million years as the Moon appears too small to cover the Sun.

What does the word “eclipse” come from?

Greek ekleipsis – meaning “abandonment” or “failure to appear.”

Which scientific theory was confirmed during a solar eclipse in 1919?

Einstein’s General Theory of Relativity (starlight was observed bending around the Sun).

Which eclipse lasts longer – solar or lunar?

Lunar eclipses (last up to a few hours) since Earth’s shadow is larger.

Which eclipse is more common?

Solar eclipses occur slightly more often but are visible from smaller areas of Earth.

What part of a solar eclipse is safe to view with the naked eye?

Only the brief totality phase; otherwise use proper solar filters.

Why is the total solar eclipse so special to observers on Earth?

The Sun and Moon have almost identical apparent sizes, allowing perfect total eclipses.