Sunday, April 26, 2020

Centennial: 'Great Debate' on Scale of Universe

Image from Earth of the center (laser points directly at center) of our Milky Way Galaxy, which was once thought to comprise the entirety of the Universe. This image was taken by European Southern Observatory astronomer Yuri  Beletsky from Paranal, Chile on 2007 July 21.
(Image Sources:, By ESO/Y. Beletsky -, CC BY 4.0,

By Glenn A. Walsh
Reporting for SpaceWatchtower

Just a century ago, the size of the Universe, and our place in the Milky Way Galaxy, were still largely not understood. One-hundred years ago today, on Monday Afternoon, 1920 April 26, two prominent astronomers debated these issues during the annual meeting of the National Academy of Sciences.

In what came to be known as the “Great Debate,” the two participants were Harlow Shapley and Heber D. Curtis. The debate lectures were delivered in the afternoon, while a panel discussion on the issues occurred that evening. The following year, the debate was published in the May issue of the Bulletin of the National Research Council, including rebuttals to the arguments in the previous year's debate.

The 1920 debate did not follow a normal debate structure. Rather, the two participants simply gave lectures on their respective viewpoints on the issues, which included responses to the other's viewpoints, but no rebuttals were given during the actual debate. At the time, both were seeking the directorship of prominent astronomical observatories, so part of the motivation of the speakers, particularly Harlow Shapley, was to impress the respective university administrations and boards of trustees.

Harlow Shapley, at the time, had been working at the Mount Wilson Observatory in southern California since 1914. In 1921, he would become Director of the Harvard College Observatory in Cambridge, Massachusetts.

As Harvard College Observatory Director, on Wednesday Evening, 1941 November 19, Dr. Shapley gave the keynote address at the dedication of a rather unique 10-inch Siderostat-type Refractor Telescope, in the public observatory of the original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center – Pittsburgh's science and technology museum from 1939 to 1991). A strong supporter of amateur astronomy, in the 1940s he also helped to establish a national organization for amateur astronomers, The Astronomical League.

At the time of the Great Debate, Heber Curtis was working at the Lick Observatory in northern California. Starting at Lick Observatory in 1902, he surveyed nebulae, which would be an integral issue in the Great Debate, particularly the nature of spiral nebulae.

The study of nebulae had been started by Lick Observatory Director James E. Keeler, when Dr. Keeler had returned to Lick Observatory as newly appointed Director in 1898. He had previously been Director of the Western University of Pennsylvania's Allegheny Observatory. However, Dr. Keeler suddenly died in 1900, leading Dr. Curtis to take-on his study of spiral nebulae. Later in 1920, Dr. Curtis would become Director of the newly-built, three-dome Allegheny Observatory, operated by the renamed University of Pittsburgh.

The nature of spiral nebulae observed by astronomers near the end of the 19th century was hotly debated by scientists of that era. Some thought the spiral nebulae were simply nearby gas clouds. Other scientists believed that they were distant “island universes,” or galaxies similar to our own Milky Way Galaxy.

For the 1920 annual meeting of the National Academy of Sciences, a debate was scheduled on the issue (actually, this was one of 14 issues disputed during the debate). Heber Curtis, who had been studying nebulae, was convinced that the spiral nebulae were independent galaxies outside of our Milky Way Galaxy. Further, Dr. Curtis conjectured that the Earth's Solar System was near the center of our rather small Milky Way Galaxy.

Dr. Curtis said, during the debate, "if the spirals are island universes it would seem reasonable and most probable to assign to them dimensions of the same order as our galaxy. If, however, their dimensions are as great as 300,000 light years [as Shapley asserted for our galaxy], the island universes must be placed at such enormous distances that it would be necessary to assign what seem impossibly great absolute magnitudes to the novae which have appeared in these objects."

Harlow Shapley, who spoke first, argued that the spiral nebulae were gas clouds within our Milky Way Galaxy, and that our galaxy was (or nearly was) the totality of the Universe. During the debate, he also stated, "Recent studies of clusters and related objects seem to me to leave no alternative to the belief that the galactic system is at least ten times greater in diameter - at least a thousand times greater in volume - than recently supposed." He also countered Dr. Curtis saying that our Solar System was really far from the center of our much larger galaxy / Universe.

During a graduate work fellowship at Princeton University, Dr. Shapley had been studying globular clusters. As the common observation at that time was that globular clusters were more concentrated in one-half of the sky, he concluded that this part of the sky included the center of the galaxy. By using Cepheid variable stars as a sort-of measuring-rod, he determined that our galaxy was much larger than most astronomers of the time thought, and our Sun was further from the center of the galaxy, as well.

As Dr. Shapley was a younger, ambitious astronomer, Dr. Curtis was a little older and more established in the astronomy field. Dr. Curtis maintained the current opinion of most astronomers that our galaxy was rather small, with our Sun close to the center of the galaxy. He demonstrated that novae in our galaxy were much brighter than novae seen in spiral nebulae, concluding that the spiral nebulae were separate and distinct galaxies in their own right. He disputed Dr. Shapley's larger size of the Milky Way Galaxy, as he did not believe that Cepheid variable stars derived valid stellar distances.

Nothing conclusive came from the Great Debate. The data used by both astronomers were not of a high enough quality to determine the true nature of spiral nebulae.

In later years, it was determined that both scientists were correct in some matters and wrong in other matters. Dr. Curtis was correct that the Milky Way was just one of billions of galaxies in our huge Universe. However, Dr. Shapley was correct that the Milky Way galaxy is much larger than originally believed and our Sun was far from the center of the Milky Way.

By 1924, Edwin Hubble, who had started working at Mount Wilson Observatory in 1919, was able to prove that the spiral nebulae were actually galaxies, far from our own Milky Way Galaxy. Using the newly completed 100-inch Hooker Reflector Telescope (then, the world's largest telescope), he was able to identify Cepheid variable stars (used by astronomers to determine stellar distances) in several spiral nebulae, including Andromeda and Triangulum.

Dr. Hubble was able to demonstrate that these Cepheids were much too far away to be part of our own galaxy, and hence, must be in another galaxy. Consequently, he fundamentally changed the scientific view of the Universe, as well as ending the debate, in Dr. Curtis' favor, which had been the focus of the 1920 Great Debate.

About a decade later, Dr. Shapley was proven correct regarding the fact that our Milky Way Galaxy is much larger than originally believed. And, that our Solar System is far from the center of the galaxy.

Robert J. Trumpler had proven the existence of interstellar absorption. Combined with a better understanding of stellar distances and distribution of globular clusters, it became clear that our Sun was not near the center of the Milky Way Galaxy.

Under the auspices of the George Ellery Hale Lecture series, Dr. Shapley and Dr. Curtis delivered the lectures in the Baird Auditorium of the Smithsonian Institution’s Museum of Natural History, in Washington DC. The National Academy of Science's own building in Washington was not finished until 1924; from then on, annual meetings occurred in the Academy's building.

The 1920 Great Debate became the first of several such great debates regarding current issues in astronomy. To mark the 75th anniversary of the original Great Debate, other such great debates were held in the 1990s, and they continued to occur in the Baird Auditorium. These other great debates occurred in 1995 (Distance Scale to Gamma-ray Bursts), 1996 (again, regarding the Scale of the Universe), and 1998 (Nature of the Universe).

Internet Links to Additional Information ---

Internet links to more detailed information on the Great Debate:
Link >>>

Heber D. Curtis: Link >>>

Harlow Shapley: Link >>>

Edwin Hubble: Link >>>

James E. Keeler: Link >>>

Harlow Shapley and Buhl Planetarium Assist in Creation of The Astronomical League:
Link >>>

Related Blog Posts ---

"100 Years Ago: Shapley Discovers True Magnitude of Milky Way & True Location of Earth in Galaxy." 2018 Jan. 8.

Link >>>


"75th Anniversary: America's 5th Public Observatory." 2016 Nov. 19.

Harlow Shapley gave keynote address at the dedication of the rather unique 10-inch Siderostat-type Refractor Telescope at the original Buhl Planetarium and Institute of Popular Science / Buhl Science Center, Pittsburgh's science and technology museum from 1939 to 1991.

Link >>>

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Sunday, 2020 April 26.

                             Like This Post?  Please Share!

           More Astronomy & Science News - SpaceWatchtower Twitter Feed:
            Link >>>

        Astronomy & Science Links: Link >>>

                Want to receive SpaceWatchtower blog posts in your in-box ?
                Send request to < >.


Glenn A. Walsh, Informal Science Educator & Communicator: >
Electronic Mail: < >
Project Director, Friends of the Zeiss: < >
SpaceWatchtower Editor / Author: < >
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < >
* Adler Planetarium, Chicago:
  < >
* Astronomer, Educator, Optician John A. Brashear:
  < >
* Andrew Carnegie & Carnegie Libraries:
  < >


  1. We are independent company Offering Loan at a cheapest interest(2%). We guarantee any kind of Loan, Government finance Project and Investor Project. etc If you are interested Kindly get back to me for more information via Email:

    1. I was searching for loan to sort out my bills& debts, then i saw comments about Blank ATM Credit Card that can be hacked to withdraw money from any ATM machines around you . I doubted thus but decided to give it a try by contacting {} they responded with their guidelines on how the card works. I was assured that the card can withdraw $5,000 instant per day & was credited with$50,000,000.00 so i requested for one & paid the delivery fee to obtain the card, after 24 hours later, i was shock to see the UPS agent in my resident with a parcel{card} i signed and went back inside and confirmed the card work's after the agent left. This is no doubts because i have the card & has made used of the card. This hackers are USA based hackers set out to help people with financial freedom!! Contact these email if you wants to get rich with this Via: ..    


    2. Are you looking for genuine loan? contacting the right company for legitimate loan lender have always been a huge problem to clients who have financial problem and in need of solution to it at an affordable interest rate? Are you in any financial mess or do you need funds to start up your own home project and real estate development? Do you need a loan to start a nice small or large scale and medium business?
      contact us today ( Text/Call +905488241881
      Look forward to your response,

      FRANK JR
      WHATSAPP +905488241881
      APPLY TODAY FOR AFFORDABLE 100% LEGITIMATE HOME/REAL ESTATE/PERSONAL/BUSINESS LOANS Email for immediate response: ( Text/Call +905488241881

  2. We are independent company Offering Loan at a cheapest interest(2%). We guarantee any kind of Loan, Government finance Project and Investor Project. etc If you are interested Kindly get back to me for more information via Email:

  3. Hello, Do you need a quick Loan?
    I'm Susan Benson I'm a lender and also a financial consultant.

    In view of the economic stagnation the world is going through as a result of the emerging Corona-virus disease (COVID-19) a lot of people are facing untimely financial challenges. And with the presence of cash surplus in our institution, we aim to speed up money circulation by financing clients within and outside Europe with a loan.

    If you need an urgent loan to start up a business, buy a house or a car, or You need a loan for other personal reasons? I want you to contact my firm. We render all kind of loan services both secured and unsecured loans. If you are reading this and you know that you need Financial support, you can just write to us via Email: or Message me directly on WhatsApp via: +447903159998 & receive a response in an instant.

    We are a comprehensive financial service company and we are committed to help you improve your long-term and short-term financial goals because your financial stability is our ultimate goal.

    Features & Benefit;
    * Convenience - You can Apply for a loan anytime, anywhere.
    * Flexible Amount - You decide how much you want to borrow.
    * Fast Direct Funding - Receive your loan within 24 hours after approval.  
    * Flexible interest rate of 3.0%.
    * High Approval Rates
    * You Get The Chance To Select the Repayment Date, either weekly, monthly or yearly for a duration of 1-30 years.
    * Simple online application.
    * Personalized guidance and expertise.
    * No hidden Charges

    A lot of people are finding it so difficult to get a loan from their local banks or other financial institutes due to some reasons.

    If you really need solution to your financial challenges, just write to my firm we will help you out with a loan. We have helped numerous number of individuals and organizations who have been facing financial difficulty all over the world. When you apply with us, you’re applying with a trusted company that cares about your financial needs, our upmost Priority is your financial stability and you’ll be taken care of  through the whole process.

    For more information about our loan offer, kindly send us your loan request via:
    Email: OR;
    WhatsApp: +447903159998

  4. We are direct providers of Fresh Cut BG, SBLC, DTC IPIP, MT103/202 GPI CASH

    TRANSFER and MTN which are specifically for lease, our bank instrument can be

    engage in PPP Trading, Discounting, signature project (s) such as Aviation,

    Agriculture, Petroleum, Telecommunication, construction of Dams, Bridges, Real

    Estate and all kind of projects. We do not have any broker chain in our offer or

    get involved in chauffer driven offers.

    We deliver with time and precision as sethforth in the agreement. Our terms and

    Conditions are reasonable, below is our instrument description.

    The procedure is very simple; the instrument will be reserved on euro clear to be

    verified by your bank, after verification an arrangement will be made for

    necessary bank documents and stock testing expenses, the cost of the Bank

    Guarantee will be paid after the delivery of the MT760,


    1. Instrument: Bank Guarantee (BG/SBLC) (Appendix A)
    2. Total Face Value: Eur 5M MIN and Eur 10B MAX (Ten Billion USD).
    3. Issuing Bank: HSBC Bank London, Credit Suisse and Deutsche Bank Frankfurt.
    4. Age: One Year, One Month
    5. Leasing Price: 6% of Face Value plus 2% commission fees to brokers.
    6. Delivery: Bank to Bank swift.
    7. Payment: MT-103 or MT760
    8. Hard Copy: Bonded Courier within 7 banking days.

    We are ready to close leasing with any interested client in few banking days, if

    interested do not hesitate to contact me direct. Email:

    We Offer Lease and Purchase BG,SBLC,DTC IPIP, MT103/202 GPI CASH TRANSFER AND MTN


    Hello my dear people, I am Linda McDonald, currently living in Austin Texas, USA. I am a widow at the moment with three kids and i was stuck in a financial situation in April 2020 and i needed to refinance and pay my bills. I tried seeking loans from various loan firms both private and corporate but never with success, and most banks declined my credit ,do not full prey to those hoodlums at there that call them self-money lender they are all scam , all they want is your money and you well not hear from them again they have done it to me twice before I met Mr. David Wilson the most interesting part of it is that my loan was transfer to me within 74hours so I will advise you to contact Mr. David if you are interested in getting loan and you are sure you can pay him back on time you can contact him via email……… ( No credit check, no cosigner with just 2% interest rate and better repayment plans and schedule if you must contact any firm with reference to securing a loan without collateral then contact Mr. David Wilson today for your loan.
    They offer all kind of categories of loan they
    Short term loan (5_10years)
    Long term loan (20_40)
    Media term loan (10_20)
    They offer loan like
    Home loan............., Business loan........ Debt loan.......
    Student loan.........., Business startup loan
    Business loan......., Company loan.............. etc
    When it comes to financial crisis and loan then David Wilson loan financial is the place to go please just tell him I Mrs. Linda McDonald direct you Good Luck.......................

  6. Get A Blank ATM CARD And Cash Good Money/Funds Pay Your Debt directly today in any ATM machine around you anywhere in the world. contact It's 100% guaranteed secure with no worries of being caught because the blank card it's already programmed and loaded with good funds in it, in such a way that's not traceable which also have a technique that makes it impossible for the CCTV to detect you, i am not a stupid man that i will come out to the public and start saying what someone have not done. For more info contact Mr john and also on how you are going to get your Card, Order yours today via Email:

    Blog Site:

    WhatsApp +13013596832

  7. Dear Sir,

    I am a direct Mandate to a genuinely renowned Investment Finance Company offering Cash & Asset Backed Financial Instruments on Lease and Sale at the best rates and with the most feasible procedures.

    Instruments offered can be put in all forms of trade and can be monetized or discounted for direct funding. For Inquiry contact.



    Whatsapp : +1(661)262-9225

    Warm Regards
    Simon Federman.

  8. Hello All ▲▲▲ I am Dianna Kent and I live in Nevada, U.S .I am a full member of the Illuminati brotherhood, and am among the 1252 lodge. ▲▲▲ Iwas ordained by the Grand-master to go out to the world and bringmore members to the Illuminati, ▲ so I was requested to get 400Recruits for the brotherhood, I have 210 new recruits already. I amlooking for only 190 more to go,▲I am sure you want to be amongthe 190 people that will be earning $500,000 monthly and a brandnew car, ▲so add me up now so we can achieve this great chanceof being rich ▲. You get to live your dream life on earth filled with luxury. so i urge you not to miss thisGreat opportunity becoming what you long wished for life email:‬ or Whats-app +1(854) 220-5771 for guidance

    Hello All ▲▲▲ I am Dianna Kent and I live in Nevada, U.S .I am a full member of the Illuminati brotherhood, and am among the 1252 lodge. ▲▲▲ Iwas ordained by the Grand-master to go out to the world and bringmore members to the Illuminati, ▲ so I was requested to get 400Recruits for the brotherhood, I have 210 new recruits already. I amlooking for only 190 more to go,▲I am sure you want to be amongthe 190 people that will be earning $500,000 monthly and a brandnew car, ▲so add me up now so we can achieve this great chanceof being rich ▲. You get to live your dream life on earth filled with luxury. so i urge you not to miss thisGreat opportunity becoming what you long wished for life email:‬ or Whats-app +1(854) 220-5771 for guidance

  9. I am a private money lender and Investor, Do you need a legit, honest,

    reputable and quick loan? I can help you with 100% guarantee loan, I am

    offering business and individual loan, More also we finance all kind of

    projects. Waiting to hear from you to enable us send you the loan application

    form or for more details contact


    C.E.O. Deby Johnson.
    Whatsapp Number: +447459797459
    Whatsapp Number: +918375004762

  10. Am Laura Mildred by name, i was diagnosed with Herpes 4 years ago i lived in pain with the knowledge that i wasn't going to ever be well again i contacted so many herbal doctors on this issue and wasted a large sum of money but my condition never got better i was determined to get my life back so one day i saw Mr. Morrison Hansen post on how Dr. Emu saved him from Herpes with herbal medicine i contacted Dr. Emu on his Email: we spoke on the issue i told him all that i went through and he told me not to worry that everything will be fine again so he prepared the medicine and send it to me and told me how to use it, after 14 days of usage I went to see the doctor for test,then the result was negative, am the happiest woman on earth now thanks to Dr. Emu God bless you. Email him at: Call or Whats-app him: +2347012841542