Name: 101科學教室：月食《國家地理》雜誌 (101科學教室：月食《國家地理》雜誌)
Uploaded: 2025-04-21T01:27:46.000Z
Duration: 3 min 15 s

A lunar eclipse happens when the earth blocks some or all of the sun's direct light from reaching the moon.

當地球阻擋部分或全部太陽直射光到達月球時，就會發生月食。

This cosmic event only takes place during a full moon.

這一宇宙事件只在滿月時發生。

Which happens once every 29 and a half days, or the length of one full orbit of the moon around the earth.

每 29 天半發生一次，也就是月球繞地球一週的時間。

So why don't we have an eclipse every month?

那麼，為什麼不是每個月都有日食呢？

The moon's orbit is tilted a few degrees in relation to the earth, so the earth, moon, and sun don't always align.

月球的軌道相對於地球傾斜了幾度，是以地球、月球和太陽並不總是對齊的。

When the earth does eclipse the sun, it casts two types of shadows on the moon, a larger shadow known as the penumbra, and a smaller, darker shadow known as the umbra.

當日食發生時，地球會在月球上投下兩種陰影，一種較大的陰影稱為半影，另一種較小的暗影稱為本影。

The first is a total lunar eclipse, when the sun, moon and earth are in perfect alignment, and the moon falls within the earth's umbral shadow.

第一次是月全食，此時太陽、月亮和地球完全重合，月亮落在地球的本影內。

Total lunar eclipses are the most striking of the three types because they turn the moon a sunset red.

月全食是三種類型中最引人注目的，因為它會把月亮染成夕陽紅。

While shorter blue wavelengths of light are scattered outward by the earth's atmosphere, longer red wavelengths are refracted or bent inward toward the moon, making it appear red.

波長較短的藍光會被地球大氣層向外散射，而波長較長的紅光則會被折射或向內彎曲，使月球呈現紅色。

The brightness of the moon's red glow depends upon.

The earth's atmosphere, following volcanic activity, ash can block out enough light to render the moon a darker red or even near black.

地球大氣層中的火山活動、火山灰會遮擋足夠的光線，使月球變成暗紅色甚至接近黑色。

A partial lunar eclipse, the second type, occurs when the earth, moon and sun don't perfectly align, so only part of the moon passes into earth's umbra.

月偏食是第二種類型，發生時地球、月亮和太陽並不完全對齊，是以只有部分月亮進入地球本影。

Earth's shadow appears very dark on the side of the moon facing earth.

地球的影子在月球面向地球的一面顯得非常暗。

Last, a penumbral lunar eclipse occurs when the moon passes through earth's penumbral shadow.

最後，半影月食發生在月球穿過地球半影時。

The event is so subtle that most people don't even notice, the moon will appear just slightly darker than normal.

這一事件非常微妙，大多數人甚至不會注意到，月亮看起來只是比正常情況下稍微暗一些。

Lunar eclipses occur up to three times a year and can be observed from the entire nighttime half of the earth.

月食每年最多發生三次，可以從地球的整個夜間觀測到。

Unlike during a solar eclipse, it's safe to look at the moon with the naked eye during a lunar eclipse.

與日食不同，月食期間用肉眼觀察月球是安全的。

It is only because of the distances of the sun and moon from the earth that we are able to witness total lunar eclipses.

由於太陽和月亮與地球的距離，我們才能目睹月全食。

As the moon inches away from the earth each year, one day, billions of years from now, the moon will be too far away to fall completely within earth's umbral shadow.

隨著月球逐年遠離地球，在數十億年後的某一天，月球將因距離太遠而無法完全落入地球的本影之中。

Until then, we can occasionally enjoy seeing our own planet's shadow cast upon the largest object in the night sky.

在此之前，我們偶爾可以欣賞到我們自己星球的影子投射到夜空中最大的天體上。