Tag Archives: astronomy

Web Site Updates

I fixed some dead links and made other minor corrections and updates, but did not make any drastic changes in the longer pieces, so their style reflects the times when they were written, years or even decades ago. However, I think they are still relevant to the subjects being discussed.

Chicon 8

Thursday

On Thursday, Sept. 1, Mia McDavid and I drove to Chicago for Chicon 8: The 80th World Science Fiction Convention at the Hyatt Regency Chicago . This was our 5th Chicon. Previously we had attended:

Despite some glitches, we really enjoyed the Con, and visiting downtown Chicago again.

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Rang Gaeilge, 23ú lá Mí Feabhra 2022

Duinnín i Ráth Maonais (tuilleadh)

  • ‘Rachaidh mé féin anseo isteach, ‘arsa an Duinníneach nuair
    a shroicheadar an eaglais. ‘Ba mhaith liom cúpla focal a bheith
    agam le Tom Merrigan.’

    Tharla cruinniú coiste de chuid bhuanchoiste an aonaigh
    saothair ar siúl ar ardán an halla nuair a bhuail an Duinníneach
    isteach agus bhí an tAthair Merrigan ag déanamh eadrána idir
    seastán na gcístí agus lucht roth an áidh. Chuir sé na mná uaisle
    ar fad in aithne don Duinníneach, a gheall go dtiocfadh sé chun
    aonaigh agus go gceannódh sé stocaí bána cniotáilte uathu dá
    mbeidís ar fáil. D’éalaigh siad on gcruinniú ansin agus shiúil
    siad thart ar an halla, idir na stainníní, agus iad ag caint.

    ‘I’ll go in here myself,’ said Dineen when they reached the church.
    ‘I would like to have a few words with Tom Merrigan.’

    A meeting of the standing committee of the job fair was taking place on the hall stage
    when Dineen came in and Father Merrigan was mediating between the cake stand and
    the wheel of fortune. He introduced all the ladies to Dineen, who promised to come to the
    fair and buy white knitted socks from them if available. They then escaped from the meeting and walked around the hall, between the booths, talking.

    coiste jury, committee m
    buanchoiste Standing committee m
    ardán platform, stage, stand m
    eadráin Separation of combatants; intervention in dispute; mediation, conciliation f gs eadrána
    seastán stand m
    roth wheel n
    ádh luck m gs áidh
    lucht Content, charge; fill, capacity; cargo, load;
    Class, category, of) people
    m
    geall pledge, security m
    stainnín Stand, stall, booth m
  • Léigh tuilleadh

    Capricon Notes

    As I wrote previously , Mia (my wife) and I spent last weekend at Capricon, a Chicagoland science fiction convention. We went to most of the Capricons in the ’80’s and ’90’s, but in our first years in Minnesota the pressures of parenthood prevented us from going. Those have eased somewhat and we have been to most of the Capricons (and Windycons) since 2009. While most Capricons have been in the Chicago suburbs, this year the convention was downtown, at the Sheraton Grand Hotel.

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    Black Hole Lifetimes

    Black holes are not totally black! They will evaporate by Hawking radiation. This is required by Thermodynamics and Quantum Mechanics. All properties of a Schwarzschild Black are determined by its mass, so if you know the mass the lifetime and other properties follow automatcally. Or you can start with the lifetime and determine the initial mass. Or the Schwarzschild radius, or the temperature, or the entropy, etc. For black holes comparable in mass to “normal” astronomical objects this lifetime is much longer than the current age of the universe. Viktor Toth’s Hawking radiation calculator is a convenient tool for such calculations. Here are some results:

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    Blinking Astronomical Photographs

    Low-Cost Approach to Scanning Historic Glass Plates Yields an Astronomical Surprise. Technical details at Precise Photometric Measurements from a 1903 Photographic Plate Using a Commercial Scanner.

    Professional astrophotography used to be done on emulsion-coasted glass places. That was how astromical discoveries were made for nearly a century.

    More than an estimated 2.4 million glass plates are out there in collections in North America alone. These were taken starting in the 1890s right up until the 1970s, when CCD (Charged Couple Device) detectors started to come online for astronomy. Of these, only an estimated 400,000 plates have been digitized to research quality

    The team in this article has found a much cheaper way to proceed with this process, using off-the-shelf hardware.

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    Supernovae

    I went (via Zoom) to a great lecture last night. Serafina Nance spoke to the The Calgary Centre of the Royal Astronomical Society of Canada on Tracing the Lives, Deaths, and Explosions of Massive Stars.

    Supernovae are cosmic events of gigantic power. Their explosions can shine as bright as a galaxy, a pinprick of extraordinarily bright light in the night sky. What is less well-understood, however, is which stars reach the point of explosion and how they evolve to their deaths. Interestingly, their explosions provide astronomers with key tools to uncover fundamental aspects of our Universe. While we know that the Universe is expanding at an accelerated rate due to dark energy, the rate of the expansion of the Universe is not well-constrained. Supernovae provide us with independent ways to measure this expansion and work to resolve one of the most pivotal questions in astronomy: How fast is the Universe really expanding?
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