Many astronomers believed them to be of internal origin, that is to say volcanic \u2013 quite different from our own towering volcanoes such as Vesuvius, and more akin to caldera
The rival theory attributed them to meteorite impacts.<\/p>\n
I was a strong supporter of the volcanic theory, but the evidence against it built up until even diehards like myself had no choice but to admit that it was wrong.<\/p>\n
- 4 mistakes astronomers made about our Solar System<\/strong><\/em><\/a><\/li>\n<\/ul>
![\"""\"]( "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Crater Tycho, as seen by the Hubble Space Telescope. Credit: NASA, ESA, and D. Ehrenreich (Institut de Plan\u00e9tologie et d\u2019Astrophysique de Grenoble (IPAG)\/CNRS\/Universit\u00e9 Joseph Fourier)<\/span><\/figcaption><\/div>\n It now seems definite that the Moon was formed about 4.6 billion years ago by a collision<\/a> between the proto-Earth and a body roughly the size of Mars.<\/p>\n
The heat generated during the formation melted the outer layers down to a depth of several hundred kilometres; the less dense materials separated out to the surface and produced a crust.<\/p>\n
Then, between 4.4 billion and four billion years ago came the Late Heavy Bombardment, when meteorites rained down to produce the oldest basins, still miscalled \u2018seas\u2019 (lunar maria<\/a>).<\/p>\n
The Imbrium Basin<\/a> dates back perhaps 3.85 billion years.<\/p>\n
As the Great Bombardment ceased there was widespread volcanism, with magma pouring out from below the crust and flooding the basins to produce structures such as the Mare Orientale.<\/p>\n
The lava flows ceased rather suddenly, by cosmic standards, and for at least a billion years the Moon has seen very little activity.<\/p>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>\nLunar volcanoes<\/strong><\/h2>\n
The gravitational pull is much less than ours, so that there is no air; virtually any atmosphere the Moon may once have had has leaked away into space.<\/p>\n
Neither is there any water; recently it has been claimed that some water does exist inside the globe, but I must be honest and admit that I am highly sceptical.<\/p>\n
The Moon moves round Earth in 27.3 days, which is also the length of its axial rotation period.<\/p>\n
The same hemisphere is turned toward us all the time, so we always see the same side of the Moon<\/a>.<\/p>\n
![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2007\/09\/Tycho_crater-be1e5bd-e1567154259834.jpg?quality=90&resize=620%2C643"\" "\\"\"\"\\"\/")
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>\n![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/08\/Far-side-moon-lro-50b4c82-e1679302073460.jpg?quality=90&resize=620%2C413"\" "\\"\"\"\\"\/")
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