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Thread: Astronomy

  1. #1741
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    There is a lot of discussion about earlier periods of mild weather. Albert Einstein commented this in a communication to Professor Hapgood (see Note 18 p.239).

  2. #1742
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    Back to the Antarctic. The coasts of the Piri Reis map showed the Antarctic to be ice-free, even putting two ships along the coast. The Oronteus Finaeus Map of Antarctica of 1531 gives the impression of the coasts being ice-free. It is also very close to how Antarctica is portrayed today. It even had rivers flowing into the sea. In 1949 one of the Byrd Antarctic Expeditions lowered coring tubes into the sea. Three cores were taken t learn something of the climate of Antarctica.

  3. #1743
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    All three cores agree that the warm period ended about 6,000 years ago (about 4,000 BC). It was then that the glacial kind of sediment began to be deposited on the Ross Sea bottom in the most recent of Antarctic ice ages. The cores indicate that warm conditions had prevailed for a long time before that.

  4. #1744
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    An important fact about they Oronteus Finaeus map is that all the rivers on it are flowing from the mountain ranges near the coast, except those near the southern tip of South America. No rivers are shown in the deep interior. This suggests that, very possibly, when the source maps were made, the interior was already covered by the ice cap. In that case, the ice cap was an advancing continental glacier that had not yet brimmed the encircling mountain ranges to reach the sea, nor had it yet stopped the flow of rivers n the seaward side of the mountains (p.98).

  5. #1745
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    https://www.universetoday.com/139077...ld-its-oceans/

    Earth’s magnetic field is one of the most mysterious features of our planet. It is also essential to life as we know it, ensuring that our atmosphere is not stripped away by solar wind and shielding life on Earth from harmful radiation. For some time, scientists have theorized that it is the result of a dynamo action in our core, where the liquid outer core revolves around the solid inner core and in the opposite direction of the Earth’s rotation.

    In addition, Earth’s magnetic field is affected by other factors, such as magnetized rocks in the crust and the flow of the ocean. For this reason, the European Space Agency’s (ESA) Swarm satellites, which have been continually monitoring Earth’s magnetic field since its deployment, recently began monitoring Earth’s oceans – the first results of which were presented at this year’s European Geosciences Union meeting in Vienna, Austria.

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    https://www.universetoday.com/139080...e-to-discover/

    "In the course of looking for habitable planets, astronomers have used Earth as a guiding example. But would we recognize a truly “Earth-like” planet if we saw one? This question was addressed in a recent paper by two professors, one of whom is an exoplanet-hunter and the other, an Earth science and astrobiology expert. Together, they consider what advances (past and future) will be key to the search for Earth 2.0."

    Earth is still undergoing major changes to its climate as a result of global warming. A couple more centuries will see this taken even further to extremes.

  7. #1747
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    https://www.universetoday.com/139054...oyed-long-ago/

    "What if our Solar System had another generation of planets that formed before, or alongside, the planets we have today? A new study published in Nature Communications on April 17th 2018 presents evidence that says that’s what happened. The first-generation planets, or planet, would have been destroyed during collisions in the earlier days of the Solar System and much of the debris swept up in the formation of new bodies.

    This is not a new theory, but a new study brings new evidence to support it."

  8. #1748
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    Quote Originally Posted by Dreamwoven View Post
    https://www.universetoday.com/139080...e-to-discover/

    "In the course of looking for habitable planets, astronomers have used Earth as a guiding example. But would we recognize a truly “Earth-like” planet if we saw one? This question was addressed in a recent paper by two professors, one of whom is an exoplanet-hunter and the other, an Earth science and astrobiology expert. Together, they consider what advances (past and future) will be key to the search for Earth 2.0."

    Earth is still undergoing major changes to its climate as a result of global warming. A couple more centuries will see this taken even further to extremes.
    Here is the summary of the pdf of the paper"Earth as an exoplanet". It can be downloaded easily:
    "Earth as an Exoplanet
    Tyler D. Robinson
    Northern Arizona University
    Christopher T. Reinhard
    Georgia Institute of Technology
    The search for habitable and inhabited environments beyond our planet commonly focuses on analogs to
    Earth, especially in the case of exoplanets. Observations from ground-based facilities, satellites, and spacecraft
    have yielded a rich collection of data that can be used to effectively view a distant Earth within the
    context of exoplanet characterization. Application of planetary and exoplanetary remote sensing techniques
    to these datasets then enables the development of approaches to detecting signatures of habitability and life
    on other worlds. In addition, an array of models have also been used to simulate exoplanet-like datasets for
    the distant Earth, thereby providing insights that are often complementary to those from existing observations.
    Of course, Earth’s atmosphere and surface environment has evolved substantially in the 4.5 billion
    years since our planet formed. A combination of in situ geological and bio-geochemical modeling studies
    of our planet have provided glimpses of environments that, while technically bellonging to our Earth, are
    seemingly alien worlds. Understanding the myriad ways Earth has been habitable and inhabited, coupled
    with remote sensing approaches honed on the distant Earth, provides a key guide to recognizing potentially
    life-bearing environments in distant planetary systems."

    This paper is a proof how the methods of astronomical investigation are changing.
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  9. #1749
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    Quote Originally Posted by Dreamwoven View Post
    https://www.universetoday.com/139054...oyed-long-ago/

    "What if our Solar System had another generation of planets that formed before, or alongside, the planets we have today? A new study published in Nature Communications on April 17th 2018 presents evidence that says that’s what happened. The first-generation planets, or planet, would have been destroyed during collisions in the earlier days of the Solar System and much of the debris swept up in the formation of new bodies.

    This is not a new theory, but a new study brings new evidence to support it."
    "Models of planetary formation show that terrestrial planets are formed by the accretion of smaller bodies into larger and larger bodies. Follow the process long enough, and you end up with planets like Earth. The smaller bodies that join together are typically between the size of the Moon and Mars. But evidence of these smaller bodies is hard to find.

    One type of unique and rare meteorite, called a ureilite, could provide the evidence to back up the models, and that’s what fell to Earth in the Nubian Desert in 2008. Ureilites are thought to be the remnants of a lost planet that was formed in the first 10 million years of the Solar System, and then was destroyed in a collision.

    Ureilites are different than other stony meteorites. They have a higher component of carbon than other meteorites, mostly in the form of the aforementioned nanodiamonds. Researchers from Switzerland, France and Germany examined the diamonds inside 2008 TC3 and determined that they probably formed in a small proto-planet about 4.55 billion years ago."

    And here is the abstractc of the also downloadable study:

    "A large planetary body inferred from diamond inclusions in a ureilite meteorite

    Abstract
    Planetary formation models show that terrestrial planets are formed by the accretion of tens of Moon- to Mars-sized planetary embryos through energetic giant impacts. However, relics of these large proto-planets are yet to be found. Ureilites are one of the main families of achondritic meteorites and their parent body is believed to have been catastrophically disrupted by an impact during the first 10 million years of the solar system. Here we studied a section of the Almahata Sitta ureilite using transmission electron microscopy, where large diamonds were formed at high pressure inside the parent body. We discovered chromite, phosphate, and (Fe,Ni)-sulfide inclusions embedded in diamond. The composition and morphology of the inclusions can only be explained if the formation pressure was higher than 20 GPa. Such pressures suggest that the ureilite parent body was a Mercury- to Mars-sized planetary embryo."
    Last edited by Danik 2016; 04-24-2018 at 09:41 AM.
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  10. #1750
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    http://earthsky.org/earth/loggerhead...field-like-gps

    "It’s well known that loggerhead sea turtles will often return, sometimes over thousands of miles, to the beach where they hatched to lay their eggs. They use Earth’s magnetism to navigate back to their home beaches. But, as it turns out they might not always make it back to the exact beach where they were born, and instead might opt for beaches with similar magnetic properties, even if the beaches are far away from each other. It’s as if their internal GPS has just slightly mixed up addresses, said biologists from University of North Carolina at Chapel Hill, whose new research shows that loggerheads that nest on beaches with similar magnetic fields are genetically similar to one another."

  11. #1751
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    Interesting post. I didn´t know that Earth´s magnetism was involved in the turtles migration cyclus.
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  12. #1752
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    http://earthsky.org/earth/how-do-flo...move-in-unison

    I thought this was intriguing - its just a theory, though.

  13. #1753
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    Thank you DW, this is beautiful. Even the 20 or 30 doves in my street seem to move together when they fly.

    "Moving in unison": I think that is something men could learn from these birds.
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  14. #1754
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    This intrigued me too:

    Projectile cannon experiments show how asteroids can deliver water

    Date:
    April 25, 2018
    Source:
    Brown University
    Summary:
    New research shows that a surprising amount of water survives simulated asteroid impacts, a finding that may help explain how asteroids deposit water throughout the solar system.

    https://www.sciencedaily.com/release...0425162042.htm
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  15. #1755
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    http://earthsky.org/earth/what-is-an-airplane-glory

    I've been on many plane journeys but never seen a glory...

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