Astronomical Info / 天文資訊 > Special Events / 特別項目 > Partial Lunar Eclipse of July 17th, 2019 | 2019 年 7 月 17 日之月偏食 [Refresh 更新]

Quick info 快速資訊: Eclipse time (partial phase) at Hong Kong 香港可見月食 (偏食) 時間 : 2019/07/17 04:02 - 05:51 HKT

Quick links 快速連結:
- Live webcast 網上直播 - 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

The eclipse has ended. 月食已結束。

Live webcast 網上直播

Please click on the links below for live webcast and descriptions of the event. All links (on the left panel) redirect you to external websites and open in new windows.

請按下列連結以觀看網上直播及相關資訊。所有 (左方) 連結連至第三者網站並以新視窗開啟。

Provider 提供者 Notes 備註
- HKO and others 香港天文台與其他機構
- Taipei Astronomical Museum 台北天文館
- Virtual Telescope

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Information about the eclipse 是次月食資料

A partial eclipse of the moon will take place on July 17 (Hong Kong Time). The eclipse will be visible in its entirety in most of Africa, eastern Europe and the Middle East. Observers in South America and western Europe will experience the event at moonrise, while those in most of Asia and Oceania will see the eclipse at moonset. Except for the extreme eastern regions, the eclipse is not visible at all in North America.

During the eclipse, more than half of the moon will be obscured by the Earth's umbral shadow. The partial phase will last around 3 hours, and the penumbral phase will extend the duration of the eclipse by more than 1 hour 15 minutes before and after the partial phase.

一次月偏食將於香港時間 7 月 17 日發生。非洲大部分地區、東歐及中東一帶將可見整個月食過程;南美洲及西歐將見帶食月出,而亞洲及大洋洲大部分地區則見帶食月落。除極東地區外,是次月食於北美洲並不可見。

月食期間,月球超過一半面積將被地球本影遮蔽;偏食共歷時接近 3 小時,而半影月食將於偏食前後各約 1 小時 15 分鐘間可見。

Map courtesy of NASA 月食圖由美國太空總署提供

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 139 (occurring at descending node 降交點月食)
Member in the series 序列中次數 22 out of 81 | 81 次中的第 22 次
Gamma 伽馬數 -0.6430 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)
July 16 18:43:53 UTC; July 17 02:43:53 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)
July 16 20:01:43 UTC; July 17 04:01:43 HKT

Greatest eclipse

July 16 21:30:44 UTC; July 17 05:30:44 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)

July 16 22:59:39 UTC; July 17 06:59:39 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)
July 17 00:17:36 UTC; July 17 08:17:36 HKT
Information at greatest eclipse
食甚 (食分最大) 時資料
Time 時間 July 16 21:30:44 UTC; July 17 05:30:44 HKT
Penumbral Magnitude (P) and Umbral Magnitude (U) 半影食分 (P) 和本影食分 (U) P: 1.7037; U: 0.6531

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.


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Local (HK) circumstances 本地 (香港) 情況

In Hong Kong, the penumbral phase will start near 2:44 am July 17. Partial eclipse will begin at around 4:02 am and maximum eclipse will occur near 5:31 am. By then the moon will be dipping towards the horizon, and the event will be observable until moonset 20 minutes later. As maximum eclipse takes place during dawn and at an extremely low altitude (3 degrees), it is advisable to observe the event in locations completely not obscured towards the southwest and west-southwest.

香港方面,半影食將於 7 月 17 日上午約 2 時 44 分開始。偏食於上午約 4 時 02 分開始,至 5 時 31 分左右到達食甚,屆時月球將逐漸下沉並靠近地平線,月食將於 20 分鐘後隨月落結束。由於食甚於黎明時份發生且仰角極低 (只得 3 度),因此最佳觀賞位置為西南及西南偏西方完全沒有阻擋的地區。

The details are summarized in the following table:

詳細資料整理如下 :

Event for Hong Kong
Time in HKT
Lunar Altitude and Azimuth
Moon enters Earth's penumbra (penumbral eclipse starts)
月球進入地球的半影 (半影月食開始)
July 17 02:44 Altitude 高度 : 33°
Azimuth 方位角 : 220° (SW 西南)
Moon enters Earth's umbra (partial eclipse starts)
月球進入地球的本影 (初虧,月偏食開始)
July 17 04:02 Altitude 高度 : 21°
Azimuth 方位角 : 234° (SW 西南)

Greatest eclipse

July 17 05:31 Altitude 高度 : 3°
Azimuth 方位角 : 244° (WSW 西南偏西)
Moonset (partial eclipse in progress)
月落 (月偏食進行中)
July 17 05:51 Altitude 高度 : -1°
Azimuth 方位角 : 246° (WSW 西南偏西)
Information at greatest magnitude for Hong Kong
Type 類型 Partial 月偏食
Time 時間 05:31 HKT
Direction of shadow relative to the Moon 地球影子方向 (相對於月球)

Entering from the top 由月球的上方進入

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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
2020/01/10 Penumbral 半影月食 P: 0.8956; U: -0.1160 Penumbral 半影月食 2020/01/11 03:10
2020/06/05 Penumbral 半影月食 P: 0.5683; U: -0.4053 Penumbral 半影月食 2020/06/06 03:25
2020/07/05 Penumbral 半影月食 P: 0.3546; U: -0.6436 --- ---
2020/11/30 Penumbral 半影月食 P: 0.8285; U: -0.2620 Penumbral 半影月食 17:43
2021/05/26 Total 月全食 P: 1.9540; U: 1.0095 Total 月全食 19:19
2021/11/19 Partial 月偏食 P: 2.0720; U: 0.9742 Partial 月偏食 17:37 (moonrise 月出)
2022/05/16 Total 月全食 P: 2.3726; U: 1.4137 --- ---
2022/11/08 Total 月全食 P: 2.4143; U: 1.3589 Total 月全食 18:59
2023/05/05 Penumbral 半影月食 P: 0.9636; U: -0.0457 Penumbral 半影月食 2023/05/06 01:23
2023/10/28 Partial 月偏食 P: 1.1181; U: 0.1220 Partial 月偏食 2023/10/29 04:14
2024/03/25 Penumbral 半影月食 P: 0.9557; U: -0.1325 --- ---

* 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。

There will be four penumbral eclipses in 2020, three of which are visible in Hong Kong.

2020 年將出現四次半影月食,其中三次可於香港看到。

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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

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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".

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"。

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: Sun Oct 01 2023 13:22:12 HKT
Last Modified 最近修訂日期: Mon Jul 24 2023