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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.
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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.
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  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
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  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.
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  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
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  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
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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/
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  14. #134
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    Still trying to figure out what the WOW! Signal was, and where it came from.


    https://arxiv.org/abs/2011.06090

    An approximation to determine the source of the WOW! Signal

    Alberto Caballero

    In this paper it is analysed which of the thousands of stars in the WOW! Signal region could have the highest chance of being the real source of the signal, providing that it came from a star system similar to ours. A total of 66 G and K-type stars are sampled, but only one of them is identified as a potential Sun-like star considering the available information in the Gaia Archive. This candidate source, which is named 2MASS 19281982-2640123, therefore becomes an ideal target to conduct observations in the search for potentially habitable exoplanets. Another 14 potential Sun-like stars (with estimated temperatures between 5,730 and 5,830 K) are also found in the region, but information about their luminosity and radius is unknown.
    Do good work. —Virgil Ivan "Gus" Grissom

  15. #135
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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 the FRB detected from within the Milky Way Galaxy.

    https://astronomy.com/news/2020/11/a...t-radio-bursts
    Do good work. —Virgil Ivan "Gus" Grissom

  16. #136
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    6. Possible cometary strike during Young Dryas period, 12,900 years ago.

    Discovered a paper from 2010 about this, not sure if I caught it before.

    https://arxiv.org/abs/1003.0744

    Palaeolithic extinctions and the Taurid Complex

    W.M. Napier

    Intersection with the debris of a large (50-100 km) short-period comet during the Upper Palaeolithic provides a satisfactory explanation for the catastrophe of celestial origin which has been postulated to have occurred around 12900 BP, and which presaged a return to ice age conditions of duration ~1300 years. The Taurid Complex appears to be the debris of this erstwhile comet; it includes at least 19 of the brightest near-Earth objects. Sub-kilometre bodies in meteor streams may present the greatest regional impact hazard on timescales of human concern.

    ===

    Plus a paper from today about the Taurid Complex and possible cometary strikes.

    https://arxiv.org/abs/2011.13078

    Taurid Complex Smoking Gun: Detection of Cometary Activity

    Ignacio Ferrin, Vincenzo Orofino

    Using the Secular Light Curve (SLC) formalism (Ferrín, 2010), we have catalogued 88 probable members of the Taurid Complex (TC). 51 of them have useful SLCs and 34 of these (67%) exhibit cometary activity. This high percentage of active asteroids gives support to the hypothesis of a catastrophe that took place during the Upper Paleolithic (Clube and Napier, 1984), when a large short-period comet, arriving in the inner Solar System from the Kuiper Belt, experienced, starting from 20 thousand years ago, a series of fragmentations that produced the present 2P/Encke comet, together with a large number of other members of the TC. The fragmentation of the progenitor body was facilitated by its heterogeneous structure (very similar to a rubble pile) and this also explains the current coexistence in the complex of fragments of different composition and origin. We have found that (2212) Hephaistos and 169P/NEAT are active and members of the TC with their own sub-group. Other components of the complex are groups of meteoroids, that often give rise to meteor showers when they enter the terrestrial atmosphere, and very probably also the two small asteroids that in 1908 and 2013 exploded in the terrestrial atmosphere over Tunguska and Chelyabinsk, respectively. What we see today of the TC are the remnants of a very varied and numerous complex of objects, characterized by an intense past of collisions with the Earth which may continue to represent a danger for our planet.
    Do good work. —Virgil Ivan "Gus" Grissom

  17. #137
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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 seems a number of asteroids come at us from out of the Sun, a blind spot for astronomical observations.

    https://phys.org/news/2020-11-astero...med-earth.html
    Do good work. —Virgil Ivan "Gus" Grissom

  18. #138
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    Quote Originally Posted by Roger E. Moore View Post
    It seems a number of asteroids come at us from out of the Sun, a blind spot for astronomical observations.

    https://phys.org/news/2020-11-astero...med-earth.html
    I missed that question. We’ve discussed that elsewhere on the board regarding detection of potentially hazardous asteroids. There’s an idea of having observation satellites inside Earth’s orbit for better coverage. Most of these asteroids are eventually discovered anyway as their orbits take them further from the sun though.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  19. #139
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    A mysterious object temporarily orbiting Earth is a 54-year-old rocket, not an asteroid.

    https://phys.org/news/2020-12-nasa-m...-asteroid.html
    Do good work. —Virgil Ivan "Gus" Grissom

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    New Astronomical Mystery: On the hunt for a missing giant black hole. Despite searching with NASA's Chandra X-ray Observatory and Hubble Space Telescope, astronomers have no evidence that a distant black hole estimated to weigh between 3 billion and 100 billion times the mass of the Sun is anywhere to be found. This missing black hole should be in the enormous galaxy in the center of the galaxy cluster Abell 2261, which is located about 2.7 billion light years from Earth. This composite image of Abell 2261 contains optical data from Hubble and the Subaru Telescope showing galaxies in the cluster and in the background, and Chandra X-ray data showing hot gas (colored pink) pervading the cluster. The middle of the image shows the large elliptical galaxy in the center of the cluster.

    https://phys.org/news/2020-12-giant-black-hole.html
    https://www.sciencealert.com/somehow...sing-in-action
    Last edited by Roger E. Moore; 2020-Dec-18 at 12:26 PM.
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  21. #141
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    The Pleiades: The world's oldest story? Astronomers say global myths about 'seven sisters' stars may reach back 100,000 years.

    https://phys.org/news/2020-12-world-...rs-global.html
    Do good work. —Virgil Ivan "Gus" Grissom

  22. #142
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    Fast Radio Bursts: solved? Astrophysicists Unveil the Mystery of Fast Radio Bursts: Fast radio bursts, or FRBs – powerful, millisecond-duration radio waves coming from deep space outside the Milky Way Galaxy – have been among the most mysterious astronomical phenomena ever observed. Since FRBs were first discovered in 2007, astronomers from around the world have used radio telescopes to trace the bursts and look for clues on where they come from and how they’re produced. UNLV astrophysicist Bing Zhang and international collaborators recently observed some of these mysterious sources, which led to a series of breakthrough discoveries reported in the journal Nature that may finally shed light into the physical mechanism of FRBs.

    https://scitechdaily.com/astrophysic...-radio-bursts/
    Do good work. —Virgil Ivan "Gus" Grissom

  23. #143
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    In 1110, The Moon Vanished From The Sky. We May Finally Know Why: A witness to a lunar eclipse that occurred in May 1110 wrote of the exceptional darkness of the Moon during the phenomenon. "On the fifth night in the month of May appeared the Moon shining bright in the evening, and afterwards by little and little its light diminished, so that, as soon as night came, it was so completely extinguished withal, that neither light, nor orb, nor anything at all of it was seen," an observer wrote in the Peterborough Chronicle.

    https://www.sciencealert.com/in-1110...nally-know-why
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  24. #144
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    A guide to the solar system’s biggest secrets: Jupiter, the planet killer, and three other untold stories from space. Here are some celestial objects that stargazers have suspected of dodging their telescopes over the years.

    https://www.popsci.com/story/space/s...terious-parts/
    Do good work. —Virgil Ivan "Gus" Grissom

  25. #145
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    Quote Originally Posted by Roger E. Moore View Post
    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
    "When the Sun goes down, the Moon comes up. At least it usually does."

    O well ...

  26. #146
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    A possible solution to the Carbon-14 found in tree rings around 774 A.D. "In 774 AD, the Sun blasted Earth with the biggest storm in 10,000 years" (Phil Plait).

    https://www.syfy.com/syfywire/in-774...in-10000-years
    Do good work. —Virgil Ivan "Gus" Grissom

  27. #147
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    More on the "missing" supermassive black hole in the galaxy Abell 2261.

    https://scitechdaily.com/deepening-a...nt-black-hole/
    Do good work. —Virgil Ivan "Gus" Grissom

  28. #148
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    Quote Originally Posted by Roger E. Moore View Post
    A mysterious object temporarily orbiting Earth is a 54-year-old rocket, not an asteroid.

    https://phys.org/news/2020-12-nasa-m...-asteroid.html
    Earth's second moon will make a close approach to the planet next week before drifting off into space, never to be seen again. "What second moon," you ask? Astronomers call it 2020 SO – a small object that dropped into Earth's orbit about halfway between our planet and the moon in September 2020. Temporary satellites like these are known as minimoons, though calling it a moon is a bit deceptive in this case; in December 2020, NASA researchers learned that the object isn't a space rock at all, but rather the remains of a 1960s rocket booster involved in the American Surveyor moon missions. Minimoon 2020 SO will make a final close approach to Earth on Tuesday (Feb. 2) at roughly 140,000 miles (220,000 kilometers) from Earth, or 58 percent of the way between Earth and the moon. The booster will drift away after that, leaving Earth's orbit entirely by March 2021, according to EarthSky. After that, the former minimoon will be just another object orbiting the sun. The Virtual Telescope Project in Rome will host an online farewell to the object on the night of Feb. 1. NASA learned that the object has made several close approaches to Earth over the decades, even coming relatively near in 1966 – the year that the agency launched its Surveyor 2 lunar probe on the back of a Centaur rocket booster.

    https://www.sciencealert.com/earth-s...g-bye-for-good
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  29. #149
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    Curious discovery that a star seems to have a sort of "heartbeat", possibly caused by an orbiting star or planet, though that does not seem possible.

    Precise radial velocities of giant stars XV. Mysterious nearly periodic radial velocity variations in the eccentric binary ε Cygni

    Paul Heeren, Sabine Reffert, Trifon Trifonov, Ka Ho Wong, Man Hoi Lee, Jorge Lillo-Box, Andreas Quirrenbach, Torben Arentoft, Simon Albrecht, Frank Grundahl, Mads Fredslund Andersen, Victoria Antoci, Pere L. Pallé

    Using the Hamilton Echelle Spectrograph at Lick Observatory, we have obtained precise radial velocities (RVs) of a sample of 373 G- and K-giant stars over more than 12 years, leading to the discovery of several single and multiple planetary systems. The RVs of the long-period (~53 years) spectroscopic binary ϵ Cyg (HIP 102488) are found to exhibit additional regular variations with a much shorter period (~291 days). We intend to improve the orbital solution of the ϵ Cyg system and attempt to identify the cause of the nearly periodic shorter period variations, which might be due to an additional substellar companion. We used precise RV measurements of the K-giant star ϵ Cyg from Lick Observatory, in combination with a large set of RVs collected more recently with the SONG telescope, as well as archival data sets. Our Keplerian model to the RVs characterizes the orbit of the spectroscopic binary to higher precision than achieved previously, resulting in a semi-major axis of a=15.8AU, an eccentricity of e=0.93, and a minimum mass of the secondary of msini=0.265M⊙. Additional short-period RV variations closely resemble the signal of a Jupiter-mass planet orbiting the evolved primary component with a period of 291d, but the period and amplitude of the putative orbit change strongly over time. Furthermore, in our stability analysis of the system, no stable orbits could be found in a large region around the best fit. Both of these findings deem a planetary cause of the RV variations unlikely. Most of the investigated alternative scenarios, such as an hierarchical triple or stellar spots, also fail to explain the observed variability convincingly. Due to its very eccentric binary orbit, it seems possible, however, that ϵ Cyg could be an extreme example of a heartbeat system.

    https://arxiv.org/abs/2102.01999
    Do good work. —Virgil Ivan "Gus" Grissom

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