Earth and Space News: September 2011

Wednesday, September 28, 2011

Nick Howes and Faulkes Telescope Project Seek Lost Apollo 10 LM Snoopy

Summary: Royal Astronomical Society Fellow Nick Howes and Faulkes Telescope Project seek lost Apollo 10 LM Snoopy, jettisoned into solar orbit May 23, 1969.

Faulkes Telescope North (FTN), viewed inside close housing; Haleakalā Observatory, East Maui; Aug. 30, 2010: Mike Falarski, Public Domain (CC0 1.0), via Wikimedia Commons

Royal Astronomical Society Fellow Nick Howes and Faulkes Telescope Project seek lost Apollo 10 LM Snoopy, separated above Earth’s moon from the mission’s command module and sent into a solar orbit Friday, May 23, 1969.

Faulkes Telescope Project (FTP) operates as an education partner of Las Cumbres Observatory Global Telescope Network (LCOGTN), a California-headquartered global network of astronomical observatories. Faulkes Telescope Project website expresses the project’s mission as encouraging “research-based science education” by providing free access, for teachers and students, to the project’s and partners’ resources.

Faulkes Telescope Project’s twin 2-meter-aperture telescopes have complementary locations in Earth’s Southern and Northern Hemispheres. Faulkes Telescope North is located at Haleakalā Observatory, also known as Haleakalā High Altitude Observatory Site, on Hawaii’s East Maui Volcano. Faulkes Telescope South is sited at Australia’s Siding Spring Observatory on Mount Woorat, also known as Siding Spring Mountain, in Warrumbungle National Park, near Coonabarabran, New South Wales.

Founder and editor of online space history website collectSPACE Robert Zane Pearlman (born Jan. 14, 1976) notes the significance of Howes and Faulkes Telescope Project’s search in his Sept. 20, 2011, post on Space.com, the online space history website that he founded in 1999. Apollo 10 Lunar Module Snoopy is “the only U.S. once-manned spacecraft” that still roams outer space.

The Apollo 10 mission’s Command Module Charlie Brown separated from Lunar Module Snoopy Friday, May 23, 1969, at 05:13:36 Greenwich Mean Time/Coordinated Universal Time (12:13 a.m. Eastern Standard Time, 1:13 a.m. Eastern Daylight Time; 108:24:36 Ground Elapsed Time since liftoff). The lunar module’s ascent propulsion system’s (APS) 249.0-second firing, beginning at 05:41:05 GMT/UTC (12:41 a.m. EST, 1:41 a.m. EDT; 108:52:05.5 GET), placed Snoopy into a solar orbit. Snoopy’s descent stage had been placed into lunar orbit, for eventual lunar impact, after separation from the ascent stage Thursday, May 22, at 23:34:16 GMT/UTC (6:34 p.m. EST, 7:34 p.m. EDT; 102:45:16.9 GET).

The lunar modules for Apollo missions 11, 12 and 14 through 17 all had lunar impact sites. “Lost Moon” mission Apollo 13’s Lunar Module Aquarius was intentionally allowed to burn up during re-entry into Earth’s atmosphere.

Paul Roche, Faulkes Telescope Project director and head of astronomy at the University of Glamorgan in the United Kingdom’s South Wales region, references 35th U.S. President John “Jack” Fitzgerald Kennedy’s (May 29, 1917-Nov. 22, 1963) in his description of the daunting search, according to Pearlman’s collectSPACE post. In his Sept. 12, 1962, speech at Rice University football stadium in Houston, Texas, President Kennedy attributed the impetus for undertaking such ventures as going to the moon as “. . . not because they are easy, but because they are hard . . .”

Nick Howes specifies the search’s “key problem” as “a lack of solid orbital data since 1969” in United Kingdom astronomer and Meteorwatch blog creator Adrian West’s (moniker: VirtualAstro) Sept. 19, 2011, Universe Today article, “The Mission to Find the Missing Lunar Module.” Howes envisions a huge search arc encompassing up to 135 million kilometers of space.

FTP Director Paul Roche identifies data sources for extrapolating Snoopy’s trajectory as Remanzacco Observatory in northeastern Italy’s Friuli-Venezia Giulia region and the Jamesburg Earth Station (JES) in Central Coastal California’s small, rural Carmel Valley community of Cachagua. The Jamesburg Earth Station’s construction began in October 1967 and was quickly completed for opening Dec. 1, 1968, to ensure the 97-foot antenna dish’s support for Project Apollo. Also, the project has consulted with NASA’s Jet Propulsion Laboratory (JPL) and with former Mission Control flight controllers.

Both Nick Howes and Faulkes’ education director Sarah Roberts consider the lengthy search, even if unsuccessful in finding Snoopy, as useful. They mention the bonus possibility of discovering new asteroids and comets during the project’s search for Snoopy.

The takeaways for Royal Astronomical Society Fellow Nick Howes and Faulkes Telescope Project’s search for Apollo 10 LM Snoopy are that Snoopy has been orbiting the sun for 42 years and that the search area possibly covers 135 million kilometers of space.

artist's concept of lunar module jettison by Apollo command-service module; NASA ID S66-10987; created Dec. 1, 1965: Generally not subject to copyright in the United States, via NASA Image and Digital Library

Acknowledgment

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

Image credits:

Faulkes Telescope North (FTN), viewed inside close housing; Haleakalā Observatory, East Maui; Aug. 30, 2010: Mike Falarski, Public Domain (CC0 1.0), via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:LCOGT_2m.JPG

artist's concept of lunar module jettison by Apollo command-service module; NASA ID S66-10987; created Dec. 1, 1965: Generally not subject to copyright in the United States; may use this material for educational or informational purposes, including photo collections, textbooks, public exhibits, computer graphical simulations and Internet Web pages; general permission extends to personal Web pages, via NASA Image and Digital Library @ https://images.nasa.gov/details-s66-10987

For further information:

Ashford, Adrian R. “Faulkes Telescope Project Launched.” Sky & Telescope > Astronomy News. March 29, 2004.
Available @ https://www.skyandtelescope.com/astronomy-news/faulkes-telescope-project-launched/

Cernan, Eugene. The Last Man on the Moon: Eugene Cernan and America’s Race in Space. New York NY: St. Martin’s Press, 1999.

Capelotti, P.J. (Peter Joseph). “Chapter 21 Culture of Apollo: A Catalog of Manned Exploration of the Moon.” Pages 421-441. In: Ann Garrison Darrin and Beth Laura O’Leary, eds., Handbook of Space Engineering, Archaeology, and Heritage. Boca Raton FL; London, UK; New York NY: CRC Press, 2009.

Dunbar, Brian; and Kathleen Zona, ed. “Snoopy Soars With NASA at Charles Schulz Museum.” NASA > News & Features > News Topics > NASA History & People. Jan. 5, 2009.
Available @ https://www.nasa.gov/topics/history/features/snoopy.html

Gladden, Becca. “Nick Howes Talks Science and the Importance of Following Your Dreams.” CareerThoughts. Jan. 15, 2011.
Available @ http://careerthoughts.com/nick-howes/

Godwin, Robert, comp. and ed. Apollo 10: The NASA Mission Reports. Second edition. Burlington, Canada: Apogee Books, 2000.

Marriner, Derdriu. “Jettisoned LM Snoopy Descent Stage Appeared Near Taruntius Crater.” Earth and Space News. Wednesday, May 11, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/05/jettisoned-lm-snoopy-descent-stage.html

Marriner, Derdriu. “Snoopy and Charlie Brown Are Hugging Each Other in Apollo 10 Docking.” Earth and Space News. Wednesday, May 18, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/05/snoopy-and-charlie-brown-are-hugging.html

NASA JSC Web Team. “Apollo: 1963-1972.” NASA JSC (National Aeronautics and Space Administration Johnson Space Center) History Portal. Updated July 16, 2010.
Available @ https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/apollo.htm

NASA JSC Web. “Mission Transcripts: Apollo 10.” NASA JSC (National Aeronautics and Space Administration Johnson Space Center) History Portal. Updated July 16, 2010.
Available @ https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/mission_trans/apollo10.htm

National Aeronautics and Space Administration. “11.3 Photographic Results.” Apollo 10 Mission Report: 11.3-11.5. MSC-00126. Houston TX: National Aeronautics and Space Administration Manned Spacecraft Center, August 1969.
Available @ https://www.hq.nasa.gov/alsj/a410/A10_MissionReport.pdf

National Aeronautics and Space Administration. Apollo 10 Mission (AS-505) Post Launch Mission Operation Report No. 1. Report No. M-932-69-10. Washington DC: National Aeronautics and Space Administration, May 26, 1969.
Available @ https://history.nasa.gov/afj/ap10fj/pdf/a10-postlaunch-rep.pdf

National Aeronautics and Space Administration. Apollo 10 Mission Report. MSC-00126. Houston TX: National Aeronautics and Space Administration Manned Spacecraft Center, August 1969.
Available @ https://www.hq.nasa.gov/alsj/a410/A10_MissionReport.pdf

National Aeronautics and Space Administration. Apollo 10 Press Kit. Release no. 69-68. May 7, 1969. Washington DC: National Aeronautics and Space Administration, 1969.
Available @ https://www.history.nasa.gov/alsj/a410/A10_PressKit.pdf

National Aeronautics and Space Administration. Apollo 10 Technical Air-to-Ground Voice Transcription (Goss Net 1). Prepared for Data Logistics Office Test Division Apollo Spacecraft Program Office. Houston TX: National Aeronautics and Space Administration Manned Spacecraft Center, May 1969.
Available via Johnson Space Center (JSC) History Portal @ https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/mission_trans/AS10_TEC.PDF

NickAstronomer (Nick Howes). “Faulkes Telescopes.” Space Is Ace. Oct. 19, 2011.
Available @ http://spaceisace-nickastronomer.blogspot.com/2011/10/faulkes-telescopes.html

Orloff, Richard W. “Apollo 10 The Fourth Mission: Testing the LM in Lunar Orbit.” Apollo by the Numbers: A Statistical Reference: 71-88. NASA History Series. NASA SP 4029. Washington DC: NASA Headquarters Office of Policy and Plans, 2000.
Available @ https://history.nasa.gov/SP-4029.pdf

Pearlman, Robert. “The Search for Snoopy: Astronomers and Students to Look for Lost Apollo 10 Module.” collectSpace. Sept. 20, 2011.
Available @ http://www.collectspace.com/news/news-092011a.html

Pearlman, Robert Z. (Zane). “The Search for ‘Snoopy’: Astronomers & Students Hunt for NASA’s Lost Apollo 10 Module.” Space.com > Spaceflight. Sept. 20, 2011.
Available @ https://www.space.com/13010-snoopy-nasa-lost-apollo-10-lunar-module-search.html

Shepard, Alan; Deke Slayton; Jay Barbree; and Howard Benedict. Moon Shot: The Inside Story of America's Race to the Moon. Atlanta GA: Turner Publishing Inc., 1994.

Smithsonian National Air and Space Museum. “Apollo 10 (AS-505).” Smithsonian National Air and Space Museum > Missions > Apollo 10.
Available @ https://airandspace.si.edu/explore-and-learn/topics/apollo/apollo-program/orbital-missions/apollo10.cfm

STEM Learning Limited. “Teaching Astronomy in UK Schools.” STEM Learning Limited > Resources.
Available @ https://www.stem.org.uk/elibrary/resource/31566

TRW Systems Group. Apollo 10 Mission Report Supplement 2: Guidance, Navigation, and Control Systems Performance Analysis. MSC-00126. Houston TX: National Aeronautics and Space Administration Manned Spacecraft Center, November 1969.
Available @ http://www.ibiblio.org/apollo/Documents/Apollo10MissionReport-Supplement2-GuidanceAnalysis.pdf

VirtualAstro (Adrian West). “The Mission to Find the Missing Lunar Module.” Universe Today. Sept. 19, 2011.
Available @ https://www.universetoday.com/89043/the-mission-to-find-the-missing-lunar-module/

Wilkins, Alasdair. “The Search Is on for a Lost Piece of the Apollo Program’s History.” io9 Gizmodo > Space Exploration. Sept. 19, 2011.
Available @ https://io9.gizmodo.com/the-search-is-on-for-a-lost-piece-of-the-apollo-program-5841869

Williams, David R.; and E. (Edwin) Bell II, cur. “Apollo 10.” NASA Goddard Space Flight Center > NMC (NASA Space Science Data Coordinated Archive Master Catalog) > Spacecraft. Version 5.1.0, July 10, 2019.
Available @ https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-043A

Woods, W. David; Robin Wheeler; and Ian Roberts. “Apollo 10 Image Library.” NASA History > Apollo Flight Journal > The Apollo 10 Flight Journal. 2011.
Available @ https://history.nasa.gov/afj/ap10fj/as10-image-library.html

Woods, W. David; Robin Wheeler; and Ian Roberts. “Apollo 10 Mission Documents.” NASA History > Apollo Flight Journal > The Apollo 10 Flight Journal. 2011.
Available @ https://history.nasa.gov/afj/ap10fj/as10-documents.html

Wednesday, September 21, 2011

William Herschel Discovered Mimas With Newly Built 40-Foot Telescope

Summary: On Sept. 17, 1789, William Herschel discovered Mimas with his newly built 40-foot telescope, which thereby notched two Saturnian finds in 20 days.

German-British astronomer Sir William Herschel acknowledged that the “uncommon size” of the 40-foot telescope that he designed and built enabled him to detect Saturn’s sixth and seventh moons, both of which are much smaller than the five then-known Saturnian satellites: Royal Astronomical Society @RoyalAstroSoc, via Facebook Feb. 23, 2010

On Sept. 17, 1789, William Herschel discovered Mimas with his newly built 40-foot telescope, the optical instrument through which the German-British astronomer had discovered his first Saturnian moon only 20 days earlier.

William Herschel (Nov. 15, 1738-Aug. 25, 1822) detailed his design and construction of a reflecting telescope of “uncommon size” in a paper presented at the June 11, 1795, meeting of the Royal Society of London. The success of two years of observations through the 20-feet reflector that he had finished in 1783 revived Herschel’s interest in devising telescopes with wide apertures. As President of the Royal Society, Sir Joseph Banks (Feb. 24, 1743-June 19, 1820) secured the support of King George III (June 4, 1738-Jan. 29, 1820) for Herschel’s increased aperture project.

“In consequence of this arrangement I began to construct the 40-feet telescope, which is the subject of this paper, about the latter end of the year 1785,” Herschel wrote (page 349).

Herschel involved himself in every aspect of his new telescope’s design and construction. “In the whole of the apparatus none but common workmen were employed, for I made drawings of every part of it, by which it was easy to execute the work, as I constantly inspected and directed every person’s labour; though sometimes there were not less than 40 different workmen employed at the same time.”

The telescope’s “great mirror” was made of speculum metal, a mixture of copper and tin that polishes to high reflectivity. “While the stand of the telescope was preparing I also began the construction of the great mirror, of which I inspected the casting, grinding, and polishing,” Herschel reported.

Herschel’s 40-foot telescope was raised on the grounds of Observatory House, Herschel’s home in Slough, Berkshire, South East England. Herschel’s first view through his optical invention, which occurred on Feb. 19, 1787, was disappointing. “I do not however date the completing of the instrument till much later; for the first speculum, by a mismanagement of the person who cast it, came out thinner on the centre of the back than was intended, and on account of its weakness would not permit a good figure to be given to it” (page 350).

A second mirror cast Jan. 26, 1788, cracked during cooling. A recast on Feb. 16, “. . . with particular attention to the shape of the back, . . . proved to be of a proper degree of strength.”

Although he was able to discern Saturn on Oct. 24, 1788, Herschel remained dissatisfied with his new telescope. He persisted in finessing the great mirror over the next 10 months. Finally, on Aug. 27, 1789, “. . . it was tried upon the fixed stars, and I found it to give a pretty sharp image. Large stars were a little affected with scattered light, owing to many remaining scratches in the mirror,” Herschel noted.

The next night, Aug. 28, Herschel confirmed his suspicion of a sixth Saturnian moon, named Enceladus in 1847 by Herschel’s son, Sir John Herschel (March 7, 1792-May 11, 1871). “Having brought the telescope to the parallel of Saturn, I discovered a sixth satellite of that planet; and also saw the spots upon Saturn, better than I had ever seen them before, so that I may date the finishing of the 40-feet telescope from that time.”

Twenty days later, the keen observational astronomer claimed the seventh Saturnian moon (named Mimas by his son in 1847) as his second satellite discovery in the Saturnian system. In his account of these discoveries, read at the Royal Society’s Nov. 12, 1789, meeting, Herschel pinpointed his detection of the seventh satellite as occurring “. . . when it was at its greateſt elongation” (page 11).

Herschel considered his 40-foot telescope as critical to his closely spaced discoveries of Enceladus and Mimas. In his “Account of the Diſcovery of a Sixth and Seventh Satellite of the Planet Saturn,” Herschel stated: “It may appear remarkable, that theſe ſatellites ſhould have remained ſo long unknown to us, when, for a century and an half paſt, the planet to which they belong has been the object of almoſt every aſtronomer’s curioſity, on account of the ſingular phaenomena of its ring. But it will be ſen preſently, from the ſituation and ſize of the ſatellites, that we could hardly expect to diſcover them till a teleſcope of the dimenſions and aperture of my forty-feet reflector should be conſtructed . . .” (page 2).

The takeaways for William Herschel’s discovery of Mimas with his newly built 40-foot telescope on Sept. 17, 1789, are that the German-British astronomer’s new telescope of “uncommon size” notched detection of Enceladus and Mimas, as Saturn’s sixth and seventh known moons, within the space of only 20 days; that Herschel’s first view through his new optical instrument occurred Feb. 19, 1787; that he finessed the telescope’s great mirror for two and one-half more years; and that he dated the completion of the 40-foot telescope to his discovery of Enceladus on Aug. 28, 1789.

first speculum metal mirror, cast in 1785, for William Herschel’s 40-foot telescope; Science Museum, South Kensington, London, United Kingdom; object number 1932-567 Pt1; September 2008: Geni, CC BY SA 4.0 International, via Wikimedia Commons

Acknowledgment

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

Image credits:

Dreyer, J.L.E. (John Louis Emil), comp. The Scientific Papers of Sir William Herschel Including Early Papers Hitherto Unpublished. Vol. I; Vol. II. London, England: The Royal Society and The Royal Astronomical Society, 1912.
Vol. I: Available via HathiTrust @ https://babel.hathitrust.org/cgi/pt?id=mdp.39015010954678
Vol. II: Available via HathiTrust @ https://babel.hathitrust.org/cgi/pt?id=mdp.39015010954744
Vol. I: Available via Internet Archive @ https://archive.org/details/scientificpapers032804mbp/
Vol. II: Available via Internet Archive @ https://archive.org/details/scientificpapers02hersuoft/

Herschel, William. “XXVII. Catalogue of One Thouſand new Nebulae and Cluſters of Stars. Read April 27, 1786.” Philosophical Transactions of the Royal Society of London, vol. LXXVI for the Year 1786, Part II: 457-499. London, England: Lockyer Davis and Peter Elmsly, Printers to The Royal Society, MDCCLXXXVI (1786).
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/48283813

Herschel, John F.W., Sir. “Chapter VI. Observations of the Satellites of Saturn.” Results of Astronomical Observations Made During the Years 1834, 5, 6, 7, 8, at the Cape of Good Hope; Being the Completion of a Telescopic Survey of the Whole Surface of the Visible Heavens: 414-430. London, England: Smith, Elder and Co., 1817.
Available via Internet Archive @ https://archive.org/details/resultsofastrono00hers/page/414

Herschel, William. “I. Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn; With Remarks on the Construction of Its Ring, Its Atmosphere, Its Rotation on an Axis, and Its Spheroidical Figure. Read November 12, 1789.” Philosophical Transactions of the Royal Society of London, vol. LXXX, for the Year 1790, Part I: 1-20. London UK: Lockyer Davis and Peter Elmsly, Printers to The Royal Society, MDCCXC (1790).
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51828893

Herschel, William. “XVI. An Account of the Discovery of Two Satellites Revolving Round the Georgian Planet. Read Feb. 15, 1787.” Philosophical Transactions of the Royal Society of London, vol. LXXVII for the Year 1787, Part I: 125-129. London, England: Lockyer, Davis, and Peter Elmsly, Printers to The Royal Society, MDCCLXXXVII (1787).
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51827589
Available via Internet Archive @ https://archive.org/details/philtrans05978816

Herschel, William. “XVIII. Description of a Forty-Feet Reflecting Telescope. Read June 11, 1795.” Philosophical Transactions of the Royal Society of London for the Year MDCCXCV, vol. LXXXV, Part II: 347-409. London UK: Peter Elmsly, Printer to The Royal Society, 1795.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51831451

Levy, David H. Skywatching. Revised and updated. San Francisco CA: Fog City Press, 1994.

Marriner, Derdriu. “Mimantean Crater Herschel Honors Mimas Discoverer William Herschel.” Earth and Space News. Wednesday, Sept. 7, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/09/mimantean-crater-herschel-honors-mimas.html

Marriner, Derdriu. “William Herschel Discovered Saturnian Moon Mimas Sept. 17, 1789.” Earth and Space News. Wednesday, Sept. 14, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/09/william-herschel-discovered-saturnian.html

Moore, Patrick, Sir. Philip’s Atlas of the Universe. Revised edition. London UK: Philip’s, 2005.

Pearson, W. (William), Rev. Plates Belonging to the Second Volume of An Introduction to Practical Astronomy. N.P., n.d.
Available @ https://digital.tcl.sc.edu/digital/collection/ariail2/id/151

Pearson, W. (William), Rev. “XV. The Herschelian Forty-Feet Telescope (Plate VIII).” An Introduction to Practical Astronomy: Containing Descriptions of the Various Instruments, That Have Been Usefully Employed in Determining the Places of the Heavenly Bodies, With an Account of the Methods of Adjusting and Using Them. Vol. II: 71-78. London, England: Printed for the Author by Messrs. Longman, Rees, Orme, Brown, and Green, 1829.
Available via HathiTrust @ https://hdl.handle.net/2027/nyp.33433090845102?urlappend=%3Bseq=101

Royal Astronomical Society @RoyalAstroSoc. “The logo of the Royal Astronomical Society. It is in the form of a roundel and features: -- The 40-foot telescope built by William Herschel (our first president) -- The year the Society was founded -- Our Latin motto, 'quicquid nitet notandum' -- which translates as 'whatever shines should be observed.'” Facebook. Feb. 23, 2010.
Available @ https://www.facebook.com/RoyalAstroSoc/photos/a.448029939520/335261579520/

The Royal Society. “William Herschel.” The Royal Society > Science in the Making.
Available @ https://makingscience.royalsociety.org/s/rs/people/fst01800987

Wednesday, September 14, 2011

William Herschel Discovered Saturnian Moon Mimas Sept. 17, 1789

Summary: German-British astronomer William Herschel discovered Saturnian moon Mimas Sept. 17, 1789, after having discovered Enceladus 20 days earlier.

German-British astronomer Sir William Herschel’s depiction of lineup of seven Saturnian moons on Oct. 18, 1789, at 9:22 p.m. (21:22.45), with his two discoveries, 6 and 7 (named Enceladus and Mimas approximately 58 years later, in 1847, by Sir William’s son, Sir John Herschel); star s = reference point; W. Herschel, Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn (1790), page 20: Public Domain, via Biodiversity Heritage Library

German-British astronomer William Herschel discovered Saturnian moon Mimas Sept. 17, 1789, less than three weeks after his discovery of sixth Saturnian moon Enceladus.

William Herschel (Nov. 15, 1738-Aug. 25, 1822) read his “Account of the Diſcovery of a Sixth and Seventh Satellite of the Planet Saturn” at the Nov. 12, 1789, meeting of the Royal Society of London for Improving Knowledge. He said of his discoveries’ primary body: “The planet Saturn is, perhaps, one of the moſt engaging objects that aſtronomy offers to our view. As ſuch it drew my attention ſo early as the year 1774; when, on the 17th of March, with a 5 1/2-feet reflector, I ſaw its ring reduced to a very minute line, as repreſented in fig. I (Tab. I.)” (page 2).

Herschel explained in his account that he had to delay confirmation of his sightings and suspicions of more than five Saturnian moons until completion of his powerful 40-foot- (12-meter-) focal length telescope.

“In the year 1788 very little could be done towards a diſcovery, as my twenty-feet ſpeculum was ſo much tarniſhed by zenith ſweeps, in which it had been more than uſually expoſed to falling dews, that I could hardly ſee the Georgian ſatellites” (page 10), Herschel explained.

He began construction of his powerful telescope “about the latter end of the year 1785,” according to his paper, “Description of a Forty-feet Reflecting Telescope” (page 349), read at the Society’s June 11, 1795, meeting. Although Herschel made his first view through the telescope on Feb. 19, 1787, he did not consider the telescope completed until two and one-half years later.

“Aug. the 28th, 1789. Having brought the telescope to the parallel of Saturn, I discovered a sixth satellite of that planet; and also saw the spots upon Saturn, better than I had ever seen them before, so that I may date the finishing of the 40-feet telescope from that time,” Herschel noted (page 350).

After his Aug. 28 discovery of Saturn’s sixth moon, Herschel continued to scrutinize Saturn: “I continued my obſervations conſtantly, whenever the weather would permit; and the great light of the forty-feet ſpeculum was now of ſo much uſe, that I alſo, on the 17th of September, detected the ſeventh ſatellite, when it was at its greateſt preceding elongation” (page 11).

Herschel compiled his observations of his two Saturnian satellite discoveries in a table of motion. From his table of the moons’ current positions, he made calculations of their previous placements. In comparing his calculated positions with previous years’ observations, Herschel “. . . ſoon found that many ſuſpicions of theſe ſatellites, in the ſhape of protuberant points on the arms, were confirmed, and ſerved to correct the tables, ſo as to render them more perfect” (page 11).

Mimas’ discoverer described it as “. . . incomparably ſmaller than the ſixth; and, even in my forty-feet reflector, appears no bigger than a very ſmall lucid point.” Yet, despite the seventh’s smallness, Herschel added: “I ſee it, however, alſo very well in the twenty-feet reflector . . .” The keenly experienced observer of distant astronomical objects then demystified the perception of previously unseen objects: “It muſt nevertheleſs be remembered, that a ſatellite once diſcovered is much eaſier to be ſeen than it was before we were acquainted with its place” (page 12).

Herschel determined that the seventh Saturnian satellite completed one sidereal revolution in 22 hours 40 minutes 46 seconds. He noted, however, that ascertaining the orbital period for the sixth Saturnian satellite was easier than projecting the seventh’s revolution. “The difficulty of having a number of obſervations is uncommonly great; for, on account of the ſmallneſs of its orbit, the ſatellite lies generally before and behind the planet and its ring, or at leaſt ſo near them that, except in very fine weather, it cannot eaſily be ſeen well enough to take its place with accuracy” (pages 12-13), Herschel stated.

The naming of William Herschel’s two Saturnian moons was accomplished by his son, English polymath Sir John Frederick William Herschel (March 7, 1792-May 11, 1871). In his survey of the Southern Hemisphere’s night skies, published in 1847, Sir John shared his personal, mythologically-inspired names for the then-known seven Saturnian moons: Iapetus, Titan, Rhea, Dione, Tethys, Enceladus and Mimas.

The takeaways for William Herschel’s discovery of Saturnian moon Mimas on Sept. 17, 1789, are that the German-British astronomer confirmed his suspicions of more than five Saturnian moons with his discoveries of Enceladus as the planet’s sixth moon on Aug. 28, 1789, and of Mimas as Saturn’s seventh moon three weeks later; that Herschel made his discoveries with his newly completed 40-foot telescope; and that his son, Sir John Herschel, is credited with naming his father’s Saturnian discoveries as Enceladus and Mimas.

engraving of 40-foot telescope with which Sir William Herschel discovered Saturnian moons Enceladus on Aug. 28, 1789, and Mimas on Sept. 17, 1789; “Fig. 1 represents a view of the telescope in a meridional situation, as it appears when seen from a convenient distance by a person placed towards the south-west of it” (page 350); W. Herschel, Description of a Forty-Feet Reflecting Telescope (1795), Figure 1, opposite page 408: Public Domain, via Biodiversity Heritage Library

Acknowledgment

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

Image credits:

Herschel, William. “Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn; With Remarks on the Construction of Its Ring, Its Atmosphere, Its Rotation on an Axis, and Its Spheroidical Figure. Read November 12, 1789.” Philosophical Transactions of the Royal Society of London, vol. LXXX, for the Year 1790, Part I: 1-20. London UK: Lockyer Davis and Peter Elmsly, Printers to The Royal Society, MDCCXC (1790).
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51828893

Herschel, William. “Description of a Forty-Feet Reflecting Telescope. Read June 11, 1795.” Philosophical Transactions of the Royal Society of London for the Year MDCCXCV, vol. LXXXV, Part II: 347-409. London UK: Peter Elmsly, Printer to The Royal Society, 1795.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51831451

Levy, David H. Skywatching. Revised and updated. San Francisco CA: Fog City Press, 1994.

Moore, Patrick, Sir. Philip’s Atlas of the Universe. Revised edition. London UK: Philip’s, 2005.

Wednesday, September 7, 2011

Mimantean Crater Herschel Honors Mimas Discoverer William Herschel

Summary: Mimantean crater Herschel honors Mimas discoverer William Herschel, who discovered Mimas 20 days after discovering Saturn’s sixth moon, Enceladus.

Detail shows Herschel Crater, with neighboring craters Balin and Dynas (east; right) and Oeta Chasma (north-northwest; left), on leading hemisphere of Saturnian moon Mimas; scale 1:5,000,000 (1 mm = 5 km) at 0 degrees latitude; Preliminary Pictorial Map of Mimas (IMAP 1489) prepared by U.S. Geological Survey (USGS) for the Voyager Imaging Team in cooperation with the Jet Propulsion Laboratory, California Institute of Technology and the National Aeronautics and Space Administration; 1982: Public Domain, via USGS Publication Warehouse

Mimantean crater Herschel honors Mimas discoverer William Herschel, whose discovery of Saturn’s seventh moon, Mimas, occurred 20 days after his discovery of Saturn’s sixth moon, Enceladus.

Herschel Crater prominently straddles the equator of Mimas, one of the seven ellipsoidal satellites of the sixth planet from the sun, Saturn. The huge impact crater distinguishes itself as the dominant feature on the Saturnian moon’s heavily cratered landscape. It is located on the leading hemisphere of its parent body.

Herschel Crater is centered at minus 1.38 degrees south latitude, 111.76 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. Its northernmost and southernmost latitudes extend to 18.14 degrees north and minus 21.5 degrees south, respectively. Its easternmost and westernmost longitudes stretch to 90.91 degrees west and 131.1 degrees west, respectively.

Herschel Crater’s diameter spans 139 kilometers. Its diameter equates to “nearly one-third the diameter of Mimas itself” (page 5), according to U.S. Astrogeology Science Center astrogeologist Raymind Milner Batson (July 8, 1931-May 5, 2013) in Voyager 1 and 2 Atlas of Six Saturnian Satellites, published by the National Aeronautics and Space Administration (NASA) in 1984. Batson detailed Mimas’ diameter at 394 kilometers.

Mimas’ conspicuous crater profiles as a “classic central-peak crater,” (page 424) according to planetary geologists Jeffrey Moore, Paul Schenk, Lindsey Bruesch, Erik Asphaug and William McKinnon in “Large Impact Features on Middle-Sized Icy Satellites,” published in the October 2004 issue of Icarus. They determined the central peak’s rise at approximately 6 to 8 kilometers (3.72 to 4.97 miles) above the crater’s floor.

Two craters, Balin and Dynas, lie to the east of Herschel Crater. Dynas is found almost due east of Herschel. Balin is sited to the northwest of Balin.

Balin is centered at 14.71 degrees north latitude, 82.51 degrees west longitude. The crater’s registers its northernmost and southernmost latitudes at 20.56 degrees north and 9.51 degrees north, respectively. It obtains its easternmost and westernmost longitudes at 78.33 degrees west and 88.3 degrees west, respectively. With a diameter of 35 kilometers, Balin is approximately one-fourth of Herschel Crater’s size.

Dynas is centered at 2.35 degrees north latitude, 80.71 degrees west longitude. Its northernmost and southernmost latitudes occur at 7.6 degrees north and minus 3.86 degrees south, respectively. The crater finds its easternmost and westernmost longitudes at 74.56 degrees west and 86.56 degrees west, respectively. With a diameter of 35 kilometer, Dynas is similarly sized to Balin.

Herschel’s north-northwestern rim cuts into Oeta Chasma. The degraded chasm is centered at 19 degrees north latitude, 122.7 degrees west longitude. Oeta obtains its northernmost and southernmost latitudes at 35 degrees north and 8 degrees north, respectively. The chasm marks its easternmost and westernmost longitudes at 111.4 degrees west and 132 degrees west, respectively. Oeta Chasma’s diameter measures 110 kilometers.

Mimantean crater Herschel honors German-British astronomer William Herschel (Nov. 15, 1738-Aug. 25, 1822). The IAU approved the crater’s name in 1982, during the organization’s XVIIIth (18th) General Assembly, held in Patras, Greece, from Tuesday, Aug. 17, to Thursday, Aug. 26.

William Herschel discovered Mimas on Thursday, Sept. 17, 1789. Only 20 days earlier, on Friday, Aug. 28, he had made his discovery of Enceladus as Saturn’s sixth moon.

Features on Mimas receive their names from Arthurian legend or Greek mythology. Herschel Crater stands out as the only one of the 35 named Mimantean craters with a non-Arthurian name.

Herschel Crater’s eastern neighbors, Balin and Dynas, owe their names to Arthurian legend. The Gazetteer of Planetary Nomenclature’s entries describe Sir Balin as a knight of “matchless courage and virtue” and Sir Dynas as “a knight of the Round Table.”

Balin, Dynas and 27 other Mimantean craters joined Herschel Crater in receiving approval of their names in 1982 during the IAU’s XVIIIth (18th) General Assembly. Official approval of six of the 35 named Mimantean craters was given on July 14, 2008.

The IAU also approved names from Arthurian legend and Greek mythology for eight chasmata in 1982. The Gazetteer of Planetary Nomenclature describes the origin of Oeta Chasma’s name as “Shook by a Titan in the war between Titans and Olympians.”

The takeaways for Mimantean crater Herschel’s honoring of Mimas discoverer William Herschel are that the German-British astronomer’s discovery of Saturn’s seventh satellite occurred only 20 days after his discovery of the ringed planet’s sixth satellite and that Herschel Crater claims the exclusive honor of a historical namesake among Mimas’ 35 named craters.

Artist’s rendering of interior of Mimantean crater Herschel depicts the crater’s walls and its central peaks rising above the crater’s floor, against the backdrop of Mimas’ primary, ringed planet Saturn; illustration by David Seal, mission planner and engineer at NASA’s Jet Propulsion Laboratory: National Aeronautics and Space Administration (NASA), Public Domain, via Wikimedia Commons

Acknowledgment

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

Image credits:

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Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/8807623

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Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19840027171.pdf

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Available @ http://solarviews.com/eng/mimas.htm

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Available @ https://planetarynames.wr.usgs.gov/Feature/3683

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Available @ https://planetarynames.wr.usgs.gov/Feature/1684

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