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Thread: Mysteries in Astronomy (my short list)

  1. #121
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    Quote Originally Posted by Roger E. Moore View Post
    12. Sept 1, 1859: With the 1859 Carrington event in mind (and Mystery #2), could our sun one day soon release a flare so large it could destroy our civilization?
    The Sun appears in a recent study to be quieter and less active than stars elsewhere like it, so our chances of getting fried might be less than we had feared.

    https://phys.org/news/2020-04-sun-similar-stars.html
    Last edited by Roger E. Moore; 2020-May-01 at 01:13 AM.
    Do good work. —Virgil Ivan "Gus" Grissom

  2. #122
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    59. What causes Fast Radio Bursts? This mystery might be solved thanks to the recent discovery or an FRB associated with a magnetar in our own Milky Way galaxy, the first FRB from our home galaxy ever detected.

    https://futurism.com/scientists-fast...rsts-milky-way
    https://www.sciencealert.com/a-galac...st-radio-burst
    Last edited by Roger E. Moore; 2020-May-02 at 01:36 PM.
    Do good work. —Virgil Ivan "Gus" Grissom

  3. #123
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    Quote Originally Posted by Roger E. Moore View Post
    The Sun appears in a recent study to be quieter and less active than stars elsewhere like it, so our chances of getting fried might be less than we had feared.

    https://phys.org/news/2020-04-sun-similar-stars.html
    Here is the paper itself.

    https://arxiv.org/abs/2005.01401
    [Submitted on 4 May 2020]
    The Sun is less active than other solar-like stars
    Timo Reinhold, Alexander I. Shapiro, Sami K. Solanki, Benjamin T. Montet, Nathalie A. Krivova, Robert H. Cameron, Eliana M. Amazo-Gomez
    Magnetic activity of the Sun and other stars causes their brightness to vary. We investigate how typical the Sun's variability is compared to other solar-like stars, i.e. those with near-solar effective temperatures and rotation periods. By combining four years of photometric observations from the Kepler space telescope with astrometric data from the Gaia spacecraft, we measure photometric variabilities of 369 solar-like stars. Most of the solar-like stars with well-determined rotation periods show higher variability than the Sun and are therefore considerably more active. These stars appear nearly identical to the Sun, except for their higher variability. Their existence raises the question of whether the Sun can also experience epochs of such high variability.
    Do good work. —Virgil Ivan "Gus" Grissom

  4. #124
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    Quote Originally Posted by Roger E. Moore View Post
    20. June 30, 1908: What caused the 1908 Tunguska aerial explosion over Siberia? Why was so little material from the airburst recovered despite severe damage to the ground environment?
    A new paper suggests that an iron asteroid bounced off the atmosphere and went back into space above Tunguska, never exploding.

    https://www.sciencealert.com/scienti...vent-explosion
    https://academic.oup.com/mnras/artic...dFrom=fulltext
    Do good work. —Virgil Ivan "Gus" Grissom

  5. #125
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    Quote Originally Posted by Roger E. Moore View Post
    A new paper suggests that an iron asteroid bounced off the atmosphere and went back into space above Tunguska, never exploding.
    ...
    That seems like a stretch. We saw something like that over Canada once in the 1980s IIRC, but it would be hard for it to create such a centralized blast point. Since the mnras article isn't there, merely the abstract, we can only speculate as to how they imagine this could happen.
    Forming opinions as we speak

  6. #126
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    Quote Originally Posted by antoniseb View Post
    That seems like a stretch. We saw something like that over Canada once in the 1980s IIRC, but it would be hard for it to create such a centralized blast point. Since the mnras article isn't there, merely the abstract, we can only speculate as to how they imagine this could happen.
    Great Daylight Fireball?
    https://en.wikipedia.org/wiki/1972_G...light_Fireball

    True, asteroids don't really seem to "bounce" off the atmosphere, just skim over it for a while and leave.
    Do good work. —Virgil Ivan "Gus" Grissom

  7. #127
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    Quote Originally Posted by Roger E. Moore View Post
    Great Daylight Fireball?
    https://en.wikipedia.org/wiki/1972_G...light_Fireball

    True, asteroids don't really seem to "bounce" off the atmosphere, just skim over it for a while and leave.
    Yes, that was it.
    Forming opinions as we speak

  8. #128
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    Quote Originally Posted by Roger E. Moore View Post
    21. October 28, 1937: Why do we keep failing to detect significant asteroid flybys until the objects are right upon us or have passed Earth by, from asteroid (69230) Hermes until this day?
    It appears we might be getting better at finding space rocks that come too close to Earth. The 1937 date above, btw, is the day Hermes flew by and missed us.

    https://www.space.com/asteroid-2020-...rotection.html
    Do good work. —Virgil Ivan "Gus" Grissom

  9. #129
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    Quote Originally Posted by Roger E. Moore View Post
    59. What causes Fast Radio Bursts? This mystery might be solved thanks to the recent discovery or an FRB associated with a magnetar in our own Milky Way galaxy, the first FRB from our home galaxy ever detected.

    https://futurism.com/scientists-fast...rsts-milky-way
    https://www.sciencealert.com/a-galac...st-radio-burst
    More on that FRB detected from within the Milky Way Galaxy, and its implications.

    https://arxiv.org/abs/2005.05283
    Implications of a "Fast Radio Burst" from a Galactic Magnetar
    Ben Margalit, Paz Beniamini, Navin Sridhar, Brian D. Metzger
    [Submitted on 11 May 2020]
    A luminous radio burst was recently detected in temporal coincidence with a hard X-ray flare from the Galactic magnetar SGR 1935+2154 with a time and frequency structure consistent with cosmological fast radio bursts (FRB) and a fluence within a factor of ≲30 of the least energetic extragalactic FRB previously detected. Although active magnetars are commonly invoked FRB sources, several distinct mechanisms have been proposed for generating the radio emission which make different predictions for the accompanying higher frequency radiation. We show that the properties of the coincident radio and X-ray flares from SGR 1935+2154, including their approximate simultaneity and relative fluence E-radio/E-X ∼10^−5, as well as the duration and spectrum of the X-ray emission, are consistent with extant predictions for the synchrotron maser shock model. Rather than arising from the inner magnetosphere, the X-rays are generated by (incoherent) synchrotron radiation from thermal electrons heated at the same shocks which produce the coherent maser emission. Although the rate of SGR 1935+2154-like bursts in the local universe is not sufficient to contribute appreciably to the extragalactic FRB rate, the inclusion of an additional population of more active magnetars with stronger magnetic fields than the Galactic population can explain both the FRB rate as well as the repeating fraction, however only if the population of active magnetars are born at a rate that is at least two-orders of magnitude lower than that of SGR 1935+2154-like magnetars. This may imply that the more active magnetar sources are not younger magnetars formed in a similar way to the Milky Way population (e.g. via ordinary supernovae), but instead through more exotic channels such as superluminous supernovae, accretion-induced collapse or neutron star mergers.
    Do good work. —Virgil Ivan "Gus" Grissom

  10. #130
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    Quote Originally Posted by Roger E. Moore View Post
    Mystery #10: J002E3 -- Probably the S-IVB from Apollo 12. Covered several times in this forum. Wikipedia link has a lot of data and more links.

    https://forum.cosmoquest.org/showthr...21#post2384721
    Does Junk Rot in Space?

    https://forum.cosmoquest.org/showthr...57#post2360657
    Could asteroid 2016 HO3 be another Saturn V S-IVB third stage?

    https://en.wikipedia.org/wiki/J002E3
    Wikipedia link
    New article saying it was indeed Apollo 12's SIV-B.

    https://astronomy.com/news/2020/05/h...urned-to-earth
    Do good work. —Virgil Ivan "Gus" Grissom

  11. #131
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    60. Wasn't aware of this one. Why did the Moon vanish on the night of 5/5/1110 A.D.? Probably because of volcanoes.

    https://www.syfy.com/syfywire/the-mo...-900-years-ago
    Do good work. —Virgil Ivan "Gus" Grissom

  12. #132
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    32. (more) What if the ANITA mystery was actually an illusion caused by strange ice patches under Antarctica? Totally beats me.

    https://www.livescience.com/mysterio...f-the-ice.html
    Do good work. —Virgil Ivan "Gus" Grissom

  13. #133
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    61. What just happened to the Kinman Dwarf, a giant luminous blue variable star in another galaxy that has simply vanished within the last few years?

    ABSTRACT: We investigate a suspected very massive star in one of the most metal-poor dwarf galaxies, PHL 293B. Excitingly, we find the sudden disappearance of the stellar signatures from our 2019 spectra, in particular the broad H lines with P Cygni profiles that have been associated with a massive luminous blue variable (LBV) star. Such features are absent from our spectra obtained in 2019 with the Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observation and X-shooter instruments of the European Southern Observatory’s Very Large Telescope.

    https://academic.oup.com/mnras/artic...2/1902/5863970
    https://www.cnet.com/news/a-massive-...dont-know-why/
    Do good work. —Virgil Ivan "Gus" Grissom

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