Thomas William Backhouse Clearly Saw Gegenschein Sept. 28, 1875

Summary: Victorian astronomer and meteorologist Thomas William Backhouse clearly saw the gegenschein Sept. 28, 1875, as a light phenomenon opposite the sun.

“Gegenschein above the VLT” captures diagonal band of gegenshein (top center to bottom right) over European Southern Observatory’s Very Large Telescope (VLT) at Paranal Observatory in northern Chile’s Atacama Desert; imaged October 2007 by astronomer and astrophotographer Yuri Beletsky using digital camera with 10-millimeter wide-angle lens: ESO/Y. Beletsky, CC BY 4.0 International, via ESO (European Southern Observatory) @ https://cdn.eso.org/images/large/eso0812d.jpg

Victorian astronomer and meteorologist Thomas William Backhouse clearly saw the gegenschein Sept. 28, 1875, as a “curious phenomenon” with visibility “opposite the Sun.”

Gegenschein, pronounced gay-gen-shine, is the German word for “counter glow.” The optical phenomenon’s visibility occurs at 180 degrees opposite the sun and requires dark skies. Jerry T. Bonnell and Robert J. Nemiroff, American astrophysicists and co-creators of NASA’s APOD (Astronomy Picture of the Day) website, describe the gegenschein as “sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets.”

Thomas William Backhouse (Aug. 14, 1842-March 13, 1920) reported his observations of the optical phenomenon in the Nov. 12, 1875, issue of the Monthly Notices of the Royal Astronomical Society. He made his observations in the observatory at his home, West Hendon House, in Sunderland, Tyne and Wear, North East England.

Backhouse explained that before Sept. 28, 1875, he had never noticed the light phenomenon “with such distinctness.” Backhouse’s “curious phenomenon respecting the Zodiacal Light” is now known as the gegenschein.

The gegenschein appeared Sept. 28, 1875, as “a remarkably definite oval patch of light” in the equatorial constellation of Pisces the Fishes. The patch’s diameter was about 20 degrees by 14 degrees. Four stars in Pisces (Epsilon Piscium, Omega Piscium, 21 Piscium, 29 Piscium) and two in the neighboring, equatorial constellation of Cetus the Whale (13 Ceti, 20 Ceti) established the gegenschein’s perimeter.

According to the high-precision Hipparcos Catalogue, published in 1997, Epsilon Piscium (HIP 4906) has equatorial coordinates of right ascension 23 hours 49 minutes 27.474 seconds and declination plus 01 degrees 04 minutes 34.06 seconds. Omega Piscium (HIP 118268) is found at right ascension 23 hours 59 minutes 18.687 seconds and declination plus 06 degrees 51 minutes 47.96 seconds. Equatorial coordinates for 21 Piscium (HIP 117491) are right ascension 23 hours 49 minutes 27.474 seconds and declination plus 01 degrees 04 minutes 34.06 seconds. Equatorial coordinates for 29 Piscium (HIP 145) are right ascension 00 hours 01 minutes 49.447 seconds and declination minus 03 degrees 01 minute 39.02 seconds.

The Hipparcos-determined location of 13 Ceti (HIP 2762) is right ascension 00 hours 35 minutes 14.640 seconds and declination minus 03 degrees 35 minutes 33.90 seconds. Equatorial coordinates for 20 Ceti (HIP 4147) are right ascension 00 hours 53 minutes 00.495 seconds and declination minus 01 degrees 08 minutes 39.33 seconds.

The gegenschein faded away so suddenly to the west that Backhouse at first, at 10:15 p.m., lost sight of it. Sometime afterward, he caught a faint glimpse of the gegenschein in the Pisces’ southwestern neighbor, Aquarius the Water Bearer, near Delta Aquarii.

Delta Aquarii (HIP 113136) is located at right ascension 22 hours 54 degrees 39.012 seconds and declination minus 15 degrees 49 minutes 14.85 seconds.

Backhouse perceived a more gradual, though at first rapid, fading of the gegenschein to the east of its Cetus- and Pisces-centered bright patch. Visibility was possible near the Pleiades, the open star cluster in Taurus the Bull constellation. Beyond the Pleiades, the Milky Way obscured the gegenschein.

Later, Backhouse found traces south and north of the bright patch. He tracked a faint patch southward to Iota Ceti.

Iota Ceti (HIP 1562) is located at right ascension 00 hours 19 minutes 25.674 seconds and declination minus 08 degrees 49 minutes 26.11 seconds.

Northward traces spilled into Pisces’ northwestern neighbor, Pegasus the Winged Horse constellation, and reached Gamma Pegasi in the southeastern corner of the Great Square of Pegasus asterism (recognizable pattern of stars).

Gamma Pegasi (HIP 1067) is found at right ascension 00 hours 13 minutes 14.151 seconds and declination plus 15 degrees 11 minutes 00.94 seconds.

At 10:45 p.m., Backhouse noted a lack of uniformity in the bright patch’s light. He perceived rapid concentration primarily along the ecliptic. Backhouse located the brightest part at, or one degree north of, 44 Piscium. He commented: “This point I find was exactly, to a degree, opposite the Sun.”

The Hipparcos scientific satellite places 44 Piscium (HIP 2006) at right ascension 00 hours 25 minutes 24.208 seconds and declination plus 01 degree 56 minutes 22.89 seconds.

Over the next 10 days, the point of maximum brightness made gradual eastward movements. During that time, the bright patch’s appearance became increasingly indefinite.

Backhouse puzzled over the cause of this phenomenon of zodiacal light opposite the sun. He suggested that “it is still possible that the zodiacal light is composed of particles which reflect light more readily straight towards the Sun than at other angles.”

Thomas William Backhouse’s report on the gegenschein was his first publication in the Monthly Notices of the Royal Astronomical Society, according to his obituary in the Feb. 11, 1921, issue of the Monthly Notices. His three-page report, entitled "On the Aspect of the Zodiacal Light," appeared in the journal’s Nov. 12, 1875, issue. Numbering among Backhouse’s contributions to astronomy is his Nov. 6, 1869, discovery of the Southern Taurid meteor shower.

The takeaway for Thomas William Backhouse’s clearly seeing the gegenschein Sept. 28, 1875, is that the optical phenomenon of back-scattered light from small interplanetary dust particles caught the Victorian astronomer’s attention as a bright patch centered on the neighboring equatorial constellations of Pisces the Fishes and Cetus the Whale.

West Hendon House, Sunderland, Tyne and Wear, North East England; home and observatory where Victorian astronomer and meteorologist Thomas William Backhouse studied natural phenomena; T.W. Backhouse’s "Meteorological Observations, Chiefly at Sunderland," Publications of the West Hendon House Observatory, Sunderland, No. IV (1915), frontispiece, Figures I-III: Public Domain, Google-digitized, via HathiTrust

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

“Gegenschein above the VLT” captures diagonal band of gegenshein (top center to bottom right) over European Southern Observatory’s Very Large Telescope (VLT) at Paranal Observatory in northern Chile’s Atacama Desert; imaged October 2007 by astronomer and astrophotographer Yuri Beletsky using digital camera with 10-millimeter wide-angle lens: ESO/Y. Beletsky, CC BY 4.0 International, via ESO (European Southern Observatory) @ https://www.eso.org/public/images/eso0812d/

West Hendon House, Sunderland, Tyne and Wear, North East England; home and observatory where Victorian astronomer and meteorologist Thomas William Backhouse studied natural phenomena; T.W. Backhouse’s "Meteorological Observations, Chiefly at Sunderland," Publications of the West Hendon House Observatory, Sunderland, No. IV (1915), frontispiece, Figures I-III: Public Domain, Google-digitized, via HathiTrust @ https://hdl.handle.net/2027/uiug.30112071075334?urlappend=%3Bseq=6;
via Google Books Read for Free @ https://www.google.com/books/edition/Publications_of_West_Hendon_House_Observ/RvbmAAAAMAAJ

For further information:

A. C. D. C. “Obituary . . . Fellows: . . . Thomas William Backhouse.” Monthly Notices of the Royal Astronomical Society, vol. LXXXI, issue 4 (Feb. 11, 1921): 254-255.
Available via Harvard ADSABS (NASA Astrophysics Data System) @ http://adsabs.harvard.edu/full/1919PA.....27..109B

Backhouse, T.W. (Thomas William). “Meteorological Observations, Chiefly at Sunderland.” Publications of the West Hendon House Observatory, Sunderland, No. IV. Sunderland, England: Hills & Co., 1915.
Available via HathiTrust @ https://hdl.handle.net/2027/uiug.30112071075334?urlappend=%3Bseq=7

Backhouse, T.W. (Thomas William). “On the Aspect of the Zodiacal Light Opposite the Sun.” Monthly Notices of the Royal Astronomical Society, vol. 36, issue 1 (Nov. 12, 1875): 46-48.
Available via Oxford University Press Academic @ https://academic.oup.com/mnras/article/36/1/46/1120327

King, Bob. Night Sky With the Naked Eye. Salem MA: Page Street Publishing Co., 2016.

King, Bob. “Take the Gegenschein Challenge.” Sky & Telescope > Observing. Oct. 14, 2015.
Available @ https://www.skyandtelescope.com/observing/take-the-gegenschein-challenge101420151410/

Ley, Willy. “The Puzzle Called Gegenschein.” Galaxy Magazine, vol. 19, no. 4 (April 1961): 74-79.
Available via Internet Archive @ https://archive.org/stream/Galaxy_v19n04_1961-04#page/n37/mode/1up

Marriner, Derdriu. “2018 Southern Taurids Peak Sunday Night, Oct. 28, to Pre-Dawn, Oct. 29.” Earth and Space News. Wednesday, Oct. 31, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/10/2018-southern-taurids-peak-sunday-night.html

Nemiroff, Robert (MTU); and Jerry Bonnell (UMCP). “The Gegenschein Over Chile.” NASA APOD (Astronomy Picture of the Day). Jan. 14, 2014.
Available @ https://apod.nasa.gov/apod/ap140114.html

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 145.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%20145

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 1067.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%201067

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 1562.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%201562

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 2762.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%202762

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 4147.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%204147

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 4906.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%204906

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 113136.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%20113136

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 117491.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%20117491

Space Telescope Science Institute (STScI); Space Telescope European Coordinating Facility (ST-ECF); Canadian Astronomy Data Centre (CADC). “HIP 118268.” Hubble Legacy Archive.
Available @ https://hla.stsci.edu/hlaview.html#Inventory|filterText%3D%24filterTypes%3D|query_string=HIP%20110602