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| :Also note that the Hubble Deep Field depicts approximately 50,000 <i>galaxies</i>, not just stars. See [https://en.wikipedia.org/wiki/Hubble_Deep_Field]. - [[User:Brian Kendig|Brian Kendig]] ([[User talk:Brian Kendig|talk]]) 20:50, 22 March 2022 (UTC) | | :Also note that the Hubble Deep Field depicts approximately 50,000 <i>galaxies</i>, not just stars. See [https://en.wikipedia.org/wiki/Hubble_Deep_Field]. - [[User:Brian Kendig|Brian Kendig]] ([[User talk:Brian Kendig|talk]]) 20:50, 22 March 2022 (UTC) |
| ::My error, now corrected. I was refering to the galaxies that both the comic and the HDF were enumerating, but I ''wrote'' stars - for reasons best known to my dithering mind at the time. But nice to see you're reading my waffle and actually paying attention. ;) [[Special:Contributions/172.70.162.147|172.70.162.147]] 23:18, 22 March 2022 (UTC) | | ::My error, now corrected. I was refering to the galaxies that both the comic and the HDF were enumerating, but I ''wrote'' stars - for reasons best known to my dithering mind at the time. But nice to see you're reading my waffle and actually paying attention. ;) [[Special:Contributions/172.70.162.147|172.70.162.147]] 23:18, 22 March 2022 (UTC) |
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− | I measured the size of the circle compared to the frame width (it's 1/40 of the frame width). I left the other calculations alone, but someone should probably re-scale them, as they presume that the frame is 40mm wide, which seems small for "fullscreen on your phone". Or maybe the calculations are wrong; if I had to bet between Randall and some random Internet editor (myself being included in that category) I'd bet on Randall. -- [[User:Dtgriscom|Dtgriscom]] ([[User talk:Dtgriscom|talk]]) 10:29, 23 March 2022 (UTC)
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− | I question the comment about the title text being 'sarcasm' on the basis that "we know that galaxies contain billions of stars and most of them will have planets" (I paraphrase). My view is that most of the 50,000 galaxies are likely to be very young, and we believe that the first generation of stars were large, few and short lived.
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− | As to whether they would have had multiple planets, this is an open question. Certainly, there wouldn't have been rocky planets, as the stars will have formed from the elements formed in the original big bang, which was almost exclusively Hydrogen and Helium, with essentially no heavier elements to form anything like rocky planets.
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− | Gas giant planets may have formed alongside the first massive stars, but we just don't know.[[User:Owengwynne|OwenGwynne]] ([[User talk:Owengwynne|talk]]) 12:00, 23 March 2022 (UTC)
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− | Adding to the discussion about planets in galaxies: Most galaxies in the universe are [[wikipedia:Dwarf galaxy|Dwarf Galaxies]] (see also the external sources of the Wikipedia article). DG have very distinct physical properties than our Milky Way, they contain older and/or bigger (=hotter) stars, less heavy elements (>He) and are more compact, i.e., there are more stars in less space. They also seem to have more dark matter per visible mass than larger galaxies. All of these properties make it more improbable for the stars to form planets, and even more so small rocky ones. And it probably also makes it more difficult to create life, as the cosmic vicinity of each star is much more unstable.
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− | Not relevant, but a point about the numbers involved. It's estimated that there are 200 billion galaxies in the observable universe - undoubtedly a large number. It is also estimated that there are 3 ''trillion'' trees on Earth, so maybe 15 trees for every galaxy.
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− | == Dwarfs ==
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− | The discussion ignores dwarf galaxies. Some have diameters as small as 100 light years and contain as few as 1000 stars. (Examples available at Wikipedia's "List of Satellites of the Milky Way".) Apparently the title text refers to dwarf galaxies, which could be 90% of all galaxies.
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− | Of course, there is probably no obvious limit between a dwarf galaxy and a regular galaxy. At the other end of the scale, there is no obvious limit between a dwarf galaxy and a globular cluster (or just a bunch of stars) in intergalactic space.
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