Tag Archives: astronomy

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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    Water on the Moon

    It’s confirmed. There is water on the Moon. OK, what’s the big deal? Water is very common in the cosmos and has been seen on the moon before. The difference is that previously it had been been only in craters near the lunar south pole, perpetually in darkness. Now, as the updated NASA announcement said, NASA’s SOFIA Discovers Water on Sunlit Surface of Moon, which will be much more accessible to future explorers.

    How significant this is remains to be seen, but it has provided Katie Mack with some inspiration.

    Phosphine on Venus: Not so fast

    Last month I posted about a Possible Sign of Life on Venus, which reported on Phosphine gas in the cloud decks of Venus. Earlier this month I mentioned More about phosphine on Venus. The story is not over yet.

    A Question of Phosphine links to Re-analysis of the 267-GHz ALMA observations of Venus: No statistically significant detection of phosphine. This team re-analyzed the same data used in the first Phosphine gas paper, but came to the opposite conclusion. So it comes down to a very complicated question of statistical analysis.

    Professor Coles also linked to A stringent upper limit of the PH3 abundance at the cloud top of Venus by another team which included Jane Greaves, first author of Phosphine gas in the cloud decks of Venus.

    Columbus and the Flat Earth

    Inventing the Flat Earth: Columbus and Modern Historians, by Jeffrey Burton Russell, is the book for the day. Columbus did not show the world that the Earth was round. No educated European in 1492 believed that the Earth was flat. They all knew it was round. As all math geeks know, Eratosthenes of Cyrene had made a good calculation of the circumference of the Earth about 200 BCE.

    Catholic church authorities did not say that the plan of Columbus to reach the orient by sailing westward was impossible because the Earth was flat. Their scholastic theology was based on the philosophy of Aristotle, who understood perfectly well that the Earth was round.

    There are passages in the Bible that suggest a flat Earth, but almost all theologians of ancient and medieval times knew the evidence for a round Earth was overwhelming, and understood the Bible was not to be taken literally in this and similar cases.

    The objection to the plans of Columbus was that, thanks to Eratosthenes, people had a good idea of the distance from the west coast of Europe to the east coast of China, and could easily calculate that no ship of the day could possibly carry enough supplies for the voyage.

    Columbus, acting like a 21st century Republican, rejected the best science of the day and chose a smaller alternative value for the circumference that suited his purposes. He was just lucky that the Americas happened to be there. As a result their inhabitants were then horribly unlucky.

    The story about Columbus and the flat Earth is a 19th century invention, not history.

    Also posted on Facebook.