Bookmark and Share

Astronomical Info / 天文資訊 > Special Events / 特別項目 > Total Lunar Eclipse of December 21st, 2010 | 2010 年 12 月 21 日之月全食 [Refresh 更新]

Quick info 快速資訊: Eclipse time at Hong Kong 香港可見月食時間 : 2010/12/21 17:44 - 19:04 HKT [PARTIAL ONLY 只看到月偏食]

Quick links 快速連結:
- Live webcast (Cancelled) 網上直播 (已取消) - Information about the eclipse 是次月食資料
- Local (HK) circumstances 本地 (香港) 情況 - Future lunar eclipses 未來月食
- Lunar eclipse basic knowledge 月食基礎知識 - More eclipse info 更多日月食資訊

Live webcast (Cancelled) 網上直播 (已取消)

Please click on the link below for live webcast. All links (on the left panel) redirect you to external websites and open in new windows. Additional links may be added during the eclipse. 請按下列連結以觀看網上直播。所有 (左方) 連結連至第三者網站並以新視窗開啟,而月食進行期間我們可能會增添直播連結。

Provider 提供者 Notes 備註 (All times in HKT 所有時間為香港時間)
- University of North Dakota 北達科他州立大學 (Please use Internet Explorer 請用 Internet Explorer) Grand Forks, North Dakota 大福克斯 (北達科他州)
The whole eclipse can be observed in this area. For times of eclipse stages, please refer to here. 上述地點可見整個月食過程。有關月食時間詳見這裡
Due to poor weather conditions, the above webcast is cancelled. 由於天氣情況欠佳,上述直播經已取消。

<Back to Top 返回頁頂>

Information about the eclipse 是次月食資料

A total eclipse of the moon will occur on December 21 this year. The whole North America can experience the whole event, while South America, Europe and western Africa will be able to view the eclipse near moonset (sunrise). On the other hand, observers in eastern Asia and Oceania will see the eclipse near moonrise (sunset). The eclipse is not visible in eastern Africa and western Asia.

本年 12 月 21 日將出現一次月全食,北美洲可見整個月食過程,而南美洲、歐洲和西非則可於月落/日出前見到。另一方面,東亞和大洋洲將於日落/月出後看到月食。這一次的月偏食於東非和西亞將不可見。

Map courtesy of HM Nautical Almanac Office, UK. Calculations may be slightly different from those computed by the NASA as tabulated below.
月食圖由英國 HM Nautical Almanac Office 提供,計算數據可能跟美國太空總署 (如下表示) 稍有分別。

The following shows some general details about the eclipse:

下表列出是次月食的一般性資料 :

Eclipse series and characteristics
Saros series number 沙羅序列號碼 125 (occurring at descending node 降交點月食)
Member in the series 序列中次數 48 out of 72 | 72 次中的第 48 次
Gamma 伽馬數 0.3214 earth radii 地球半徑
Time in UTC/HKT
時間 (世界協調時 / 香港時間)
P1 - Moon enters Earth's penumbra (penumbral eclipse starts)
P1 - 月球進入地球的半影 (半影月食開始)
12/21 05:29:21 UTC; 13:29:21 HKT
U1 - Moon enters Earth's umbra (partial eclipse starts)
U1 - 月球進入地球的本影 (初虧,月偏食開始)
12/21 06:32:38 UTC; 14:32:38 HKT
U2 - Moon fully enters Earth's umbra (total eclipse starts)
U2 - 整個月球進入地球的本影 (食既,月全食開始)
12/21 07:40:48 UTC; 15:40:48 HKT

Greatest eclipse

12/21 08:16:57 UTC; 16:16:57 HKT
U3 - Moon starts to leave Earth's umbra (total eclipse ends)
U3 - 月球開始離開地球的本影 (生光,月全食結束)
12/21 08:53:09 UTC; 16:53:09 HKT

U4 - Moon fully leaves Earth's umbra (partial eclipse ends)
U4 - 整個月球離開地球的本影 (復圓,月偏食結束)

12/21 10:01:19 UTC; 18:01:19 HKT
P4 - Moon fully leaves Earth's penumbra (penumbral eclipse ends)
P4 - 整個月球離開地球的半影 (半影月食結束)
12/21 11:04:28 UTC; 19:04:28 HKT
Information at greatest eclipse
食甚 (食分最大) 時資料
Time 時間 12/21 08:16:57 UTC; 16:16:57 HKT
Penumbral Magnitude (P) and Umbral Magnitude (U) 半影食分 (P) 和本影食分 (U) P: 2.2807; U: 1.2561

All places that can observe this eclipse (no matter what the Moon's position is) will experience the aforementioned events in the times indicated above.


<Back to Top 返回頁頂>

Local (HK) circumstances 本地 (香港) 情況

Hong Kong will only be able to experience the waning partial and penumbral stages after sunset that day. It will be difficult to detect the eclipse because most of the moon will have already emerged from the umbra when the moon rises.


The details are summarized in the following table:

詳細資料整理如下 :

Event for Hong Kong
Time in HKT on 2010/12/21
2010 年 12 月 21 日香港時間
Lunar Altitude and Azimuth

Sunset (eclipse already in partial stage)
日落 (偏食進行中)

17:44 Altitude 高度 : -0.8°
Azimuth 方位角 : 064.4° (ENE 東北偏東)
Moon leaves Earth's umbra (partial eclipse ends)
月球離開地球的本影 (復圓,月偏食結束)
18:01 Altitude 高度 : 2.7°
Azimuth 方位角 : 065.8° (ENE 東北偏東)
Moon leaves Earth's penumbra (penumbral eclipse ends)
月球離開地球的半影 (半影月食結束)
19:04 Altitude 高度 : 15.4°
Azimuth 方位角 : 070.8° (ENE 東北偏東)
Information at greatest magnitude for Hong Kong
Type 類型 Partial 月偏食
Time 時間 17:44 HKT
Direction of shadow relative to the Moon 地球影子方向 (相對於月球) Leaving from the top right hand side 由月球的右上方離開

<Back to Top 返回頁頂>

Future lunar eclipses 未來月食

Lunar eclipses in the next five years (click on the date to see the visible areas for that eclipse):

未來五年的月食資料 (請按下日期以觀看月食可見範圍) :

Date (UTC)
日期 (世界協調時)
Eclipse type
Eclipse type at HK
Time of greatest eclipse
2011/06/15 Total 月全食 P: 2.7117; U: 1.7050 Total 月全食 06/16 04:13
2011/12/10 Total 月全食 P: 2.2120; U: 1.1105 Total 月全食 22:32
2012/06/04 Partial 月偏食 P: 1.3428; U: 0.3759 Partial 月偏食 19:03
2012/11/28 Penumbral 半影月食 P: 0.9416; U: -0.1832 Penumbral 半影月食 22:33
2013/04/25 Partial 月偏食 P: 1.0118; U: 0.0205 Partial 月偏食 04/26 04:07
2013/05/25 Penumbral 半影月食 P: 0.0402; U: -0.9279 --- ---
2013/10/18 Penumbral 半影月食 P: 0.7908; U: -0.2666 Penumbral 半影月食 10/19 06:21 (sunrise 日出)
2014/04/15 Total 月全食 P: 2.3182; U: 1.2907 --- ---
2014/10/08 Total 月全食 P: 2.1456; U: 1.1659 Total 月全食 18:55
2015/04/04 Total 月全食 P: 2.0792; U: 1.0008 Total 月全食 20:00
2015/09/28 Total 月全食 P: 2.2296; U: 1.2764 --- ---

* P represents penumbral magnitude while U represents umbral magnitude.
* P 和 U 分別代表半影食分和本影食分。

The next total lunar eclipse visible in Hong Kong will occur in mid-2011, while the next tetrad will occur in 2014 and 2015 with two visible in Hong Kong.

下次香港可見的月全食將會於 2011 年中旬發生,而下一組連續四次全食將於 2014 / 2015 年出現,其中兩次於香港可見。

<Back to Top 返回頁頂>

Lunar eclipse basic knowledge 月食基礎知識

The following information is quoted from Wikipedia. 以下資料摘自維基百科

A lunar eclipse occurs whenever the Moon passes through some portion of the Earth's shadow. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, there is always a full moon the night of a lunar eclipse. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.


The shadow of the Earth can be divided into two distinctive parts: the umbra and penumbra. Within the umbra, there is no direct solar radiation. However, as a result of the Sun's large angular size, solar illumination is only partially blocked in the outer portion of the Earth's shadow, which is given the name penumbra.

A penumbral eclipse occurs when the Moon passes through the Earth's penumbra. The penumbra does not cause any noticeable darkening of the Moon's surface, though some may argue it turns a little yellow. A special type of penumbral eclipse is a total penumbral eclipse, during which the Moon lies exclusively within the Earth's penumbra. Total penumbral eclipses are rare, and when these occur, that portion of the Moon which is closest to the umbra can appear somewhat darker than the rest of the Moon.

A partial lunar eclipse occurs when only a portion of the Moon enters the umbra. When the Moon travels completely into the Earth's umbra, one observes a total lunar eclipse. The Moon's speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the Moon's first and last contact with the shadow is much longer, and could last up to 3.8 hours. The relative distance of the Moon from the Earth at the time of an eclipse can affect the eclipse's duration. In particular, when the Moon is near its apogee, the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease much with distance. Thus, a totally-eclipsed Moon occurring near apogee will lengthen the duration of totality.

The Moon does not completely disappear as it passes through the umbra because of the refraction of sunlight by the Earth's atmosphere into the shadow cone; if the Earth had no atmosphere, the Moon would be completely dark during an eclipse. The red colouring arises because sunlight reaching the Moon must pass through a long and dense layer of the Earth's atmosphere, where it is scattered. Shorter wavelengths are more likely to be scattered by the small particles, and so by the time the light has passed through the atmosphere, the longer wavelengths dominate. This resulting light we perceive as red. This is the same effect that causes sunsets and sunrises to turn the sky a reddish colour; an alternative way of considering the problem is to realise that, as viewed from the Moon, the Sun would appear to be setting (or rising) behind the Earth.

The amount of refracted light depends on the amount of dust or clouds in the atmosphere; this also controls how much light is scattered. In general, the dustier the atmosphere, the more that other wavelengths of light will be removed (compared to red light), leaving the resulting light a deeper red colour. This causes the resulting coppery-red hue of the Moon to vary from one eclipse to the next. Volcanoes are notable for expelling large quantities of dust into the atmosphere, and a large eruption shortly before an eclipse can have a large effect on the resulting colour.




  1. 半影食始:月球剛剛和半影區接觸,這時月球表面光度略為減少,但肉眼較難覺察。
  2. 初虧:月球由東緣慢慢進入地影,月球與地球本影第一次外切。
  3. 食既:月球進入地球本影,並與本影第一次內切。
  4. 食甚:月圓面中心與地球本影中心最接近的瞬間,此時前後月球表面呈紅銅色或暗紅色。(原因:大陽光經過地球大氣層時發生折射,使光線向內側偏折,但每種光的偏折程度不一樣(色散),紅光偏折程度最大,最接近地球陰影,映在月球上;此外,由於大氣層的灰塵及雲的含量與位置不同,光線偏折程度會有不同,因此月全食時的月球是暗紅、紅銅、或橙色的。同樣的道理,由於大氣層的折射,朝陽與夕陽不是白色的,而根據高度因為大氣折射程度不同,呈現橙色或紅色。)
  5. 生光:月球在地球本影內移動,並與地球本影第二次內切。
  6. 復圓:月球逐漸離開地球本影,與地球本影第二次外切。
  7. 半影食終:月球離開半影,整個月食過程正式完結。


Please read the Wikipedia article for more. 欲得到更多資料,請瀏覽相關條目

<Back to Top 返回頁頂>

More eclipse info 更多日月食資訊

For more information on eclipses, visit our "Eclipse Q&A" section (total 3 pages) and "Eclipse Dates and Numbers - Lunar Eclipse". "Mr." also has a very detailed description on this eclipse.

如欲得知更多有關日月食的資訊,請到本網的 "日月食問與答" 一節 (共三頁) 和 "月食日期和數字"。"Mr." 亦有對於是次月食的詳細描述。

Eclipse times and information are based on Eclipse Predictions by Fred Espenak, NASA's GSFC. NASA's lunar eclipse page: here.

Last Accessed 最近訪問日期: Mon Sep 28 2020 21:08:36 HKT
Last Modified 最近修訂日期: Tue Dec 24 2013

觀看訪客統計報表 Web Traffic Statistics