# Solar eclipse of September 23, 1987

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An annular [solar eclipse](/source/Solar_eclipse) occurred at the Moon's [descending node](/source/Lunar_node) of orbit on Wednesday, September 23, 1987,[1] with a [magnitude](/source/Magnitude_of_eclipse) of 0.9634. A [solar eclipse](/source/Solar_eclipse) occurs when the [Moon](/source/Moon) passes between [Earth](/source/Earth) and the [Sun](/source/Sun), thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's [apparent diameter](/source/Apparent_diameter) is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an [annulus](/source/Annulus_(mathematics)) (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring only 5 days after [apogee](/source/Apsis) (on September 18, 1987, at 4:00 UTC), the Moon's apparent diameter was smaller.[2]

Annularity was visible in the [Soviet Union](/source/Soviet_Union) (today's [Kazakhstan](/source/Kazakhstan)), [China](/source/China) (including [Shanghai](/source/Shanghai)), southwestern [Mongolia](/source/Mongolia), [Okinawa Islands](/source/Okinawa_Islands) of [Japan](/source/Japan) except [Kume Island](/source/Kume_Island) and the southwestern tip of [Kerama Islands](/source/Kerama_Islands), the [Federal States of Micronesia](/source/Federal_States_of_Micronesia), [Papua New Guinea](/source/Papua_New_Guinea), [Solomon Islands](/source/Solomon_Islands), Rotuma Islands of [Fiji](/source/Fiji), [Wallis Islands](/source/Wallis_Islands) and [West Samoa](/source/West_Samoa) (the name changed to Samoa later). A partial eclipse was visible for parts of [South Asia](/source/South_Asia), [Southeast Asia](/source/Southeast_Asia), [East Asia](/source/East_Asia), [Australia](/source/Australia), [Oceania](/source/Oceania), and [Hawaii](/source/Hawaii).

## Observation

Five radio observation stations were present in China at the time of the eclipse, two of which were within the annularity, in [Ürümqi](/source/%C3%9Cr%C3%BCmqi) and [Shanghai](/source/Shanghai) respectively. A partial solar eclipse was observed from the other three, including one in [Nanjing](/source/Nanjing) where the eclipse was close to annularity, and the rest two in [Beijing](/source/Beijing) and [Kunming](/source/Kunming). The Department of Mathematics and Physics of the [Chinese Academy of Sciences](/source/Chinese_Academy_of_Sciences) and the Chinese Astronomical Society held a meeting in Kunming in December 1986, deciding that on-site observation would be conducted at each station, among which the [Shanghai Astronomical Observatory](/source/Shanghai_Astronomical_Observatory) was considered to have the best location with a larger magnitude of the eclipse, longer duration and larger [solar zenith angle](/source/Solar_zenith_angle). The Shanghai Astronomical Observatory conducted observations with seven different wave bands using a 25-metre radio telescope.[3] The [Yunnan Astronomical Observatory](/source/Yunnan_Astronomical_Observatory) located in Kunming also conducted a multi-band joint observation of the partial solar eclipse.[4]

The Chinese Research Institute of Radio Wave Propagation conducted observations with a high-frequency skywave radar located in [Xinxiang](/source/Xinxiang) on the southern limit of annularity. Uneven structure and motion were observed in the [ionosphere](/source/Ionosphere), the highest operating frequency was found changed during the eclipse, and large-scale fluctuations continued after the eclipse.[5]

## Eclipse details

Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the Moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.[6]

September 23, 1987 Solar Eclipse Times Event Time (UTC) First Penumbral External Contact 1987 September 23 at 00:15:50.5 UTC First Umbral External Contact 1987 September 23 at 01:20:19.5 UTC First Central Line 1987 September 23 at 01:22:07.2 UTC First Umbral Internal Contact 1987 September 23 at 01:23:55.0 UTC First Penumbral Internal Contact 1987 September 23 at 02:33:48.6 UTC Greatest Duration 1987 September 23 at 02:45:44.7 UTC Equatorial Conjunction 1987 September 23 at 02:54:28.0 UTC Ecliptic Conjunction 1987 September 23 at 03:09:08.4 UTC Greatest Eclipse 1987 September 23 at 03:12:21.6 UTC Last Penumbral Internal Contact 1987 September 23 at 03:51:20.8 UTC Last Umbral Internal Contact 1987 September 23 at 05:01:01.1 UTC Last Central Line 1987 September 23 at 05:02:46.3 UTC Last Umbral External Contact 1987 September 23 at 05:04:31.2 UTC Last Penumbral External Contact 1987 September 23 at 06:08:54.0 UTC

September 23, 1987 Solar Eclipse Parameters Parameter Value Eclipse Magnitude 0.96337 Eclipse Obscuration 0.92807 Gamma 0.27869 Sun Right Ascension 11h58m25.1s Sun Declination +00°10'17.1" Sun Semi-Diameter 15'56.2" Sun Equatorial Horizontal Parallax 08.8" Moon Right Ascension 11h58m55.2s Moon Declination +00°23'45.5" Moon Semi-Diameter 15'07.6" Moon Equatorial Horizontal Parallax 0°55'30.9" ΔT 55.7 s

## Eclipse season

See also: [Eclipse cycle](/source/Eclipse_cycle)

This eclipse is part of an [eclipse season](/source/Eclipse_season), a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a [fortnight](/source/Fortnight).

Eclipse season of September–October 1987 September 23 Descending node (new moon) October 7 Ascending node (full moon) Annular solar eclipse Solar Saros 134 Penumbral lunar eclipse Lunar Saros 146

## Related eclipses

### Eclipses in 1987

- [A hybrid solar eclipse on March 29](/source/Solar_eclipse_of_March_29,_1987).
- [A penumbral lunar eclipse on April 14](/source/April_1987_lunar_eclipse).
- **An annular solar eclipse on September 23.**
- [A penumbral lunar eclipse on October 7](/source/October_1987_lunar_eclipse).

### Metonic

- Preceded by: [Solar eclipse of December 4, 1983](/source/Solar_eclipse_of_December_4,_1983)
- Followed by: [Solar eclipse of July 11, 1991](/source/Solar_eclipse_of_July_11,_1991)

### Tzolkinex

- Preceded by: [Solar eclipse of August 10, 1980](/source/Solar_eclipse_of_August_10,_1980)
- Followed by: [Solar eclipse of November 3, 1994](/source/Solar_eclipse_of_November_3,_1994)

### Half-Saros

- Preceded by: [Lunar eclipse of September 16, 1978](/source/September_1978_lunar_eclipse)
- Followed by: [Lunar eclipse of September 27, 1996](/source/September_1996_lunar_eclipse)

### Tritos

- Preceded by: [Solar eclipse of October 23, 1976](/source/Solar_eclipse_of_October_23,_1976)
- Followed by: [Solar eclipse of August 22, 1998](/source/Solar_eclipse_of_August_22,_1998)

### Solar Saros 134

- Preceded by: [Solar eclipse of September 11, 1969](/source/Solar_eclipse_of_September_11,_1969)
- Followed by: [Solar eclipse of October 3, 2005](/source/Solar_eclipse_of_October_3,_2005)

### Inex

- Preceded by: [Solar eclipse of October 12, 1958](/source/Solar_eclipse_of_October_12,_1958)
- Followed by: [Solar eclipse of September 1, 2016](/source/Solar_eclipse_of_September_1,_2016)

### Triad

- Preceded by: [Solar eclipse of November 22, 1900](/source/Solar_eclipse_of_November_22,_1900)
- Followed by: [Solar eclipse of July 24, 2074](/source/Solar_eclipse_of_July_24,_2074)

## Notes

1. ["September 23, 1987 Annular Solar Eclipse"](https://www.timeanddate.com/eclipse/solar/1987-september-23). timeanddate. Retrieved 9 August 2024.

1. ["Moon Distances for London, United Kingdom, England"](https://www.timeanddate.com/astronomy/moon/distance.html?year=1987&n=136). timeanddate. Retrieved 9 August 2024.

1. 纪树臣 季德盛 梁世光 (1988). "1987年9月23日沪台25米天线观测选题及方案". *云南天文台台刊*. '***(4): 100–105.***

1. 纪树臣 杨荣邦 谢瑞祥 (1989). "1987年9月23日日偏食云台多波段联合观测". *云南天文台台刊*. '***(3): 46–53.***

1. 焦培南 (1990). ["1987年9月23日日环食的电离层波动现象"](http://manu16.magtech.com.cn/geophy/CN/abstract/abstract4641.shtml). *地球物理学报*. **33** (4): 391–398. [Archived](https://archive.today/20150721080019/http://manu16.magtech.com.cn/geophy/CN/abstract/abstract4641.shtml) 21 July 2015 at the Wayback Machine.

1. ["Annular Solar Eclipse of 1987 Sep 23"](https://eclipsewise.com/solar/SEprime/1901-2000/SE1987Sep23Aprime.html). EclipseWise.com. Retrieved 9 August 2024.

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Adapted from the Wikipedia article [Solar eclipse of September 23, 1987](https://en.wikipedia.org/wiki/Solar_eclipse_of_September_23%2C_1987) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Solar_eclipse_of_September_23%2C_1987?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.