# Tag Info

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It's going to be all (or perhaps nearly all) of the observable Universe. Roughly speaking, there are several hundred billion stars in the Milky Way. And extrapolating the number of galaxies in deep Hubble images suggests something like a hundred billion galaxies in the observable Universe. Put these together and you get about $10^{22}$ to $10^{24}$ stars in ...

4

Referring to your #gravity tag this would only create a peak in the planets tidal forces. But this would be a visible effect in case the planets would be big and close enough... Last night happened that with Sun-Earth-Moon although they were not aligned as you say. To sum up: a proper alignment would increase the effect of tidal forces.

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A star is described as such whether or not it has planets. There doesn't appear to have ever been a need, and to be honest, I can't think of any need for one. When it was assumed (in historical times) that we were on the only planet, stars were not thought to have planets. The title worked then. Now, as we know most stars are likely to have planets as part ...

3

Your scenario is, of course, rather speculative and considers the very distant future. I don't like that article you're referencing, some stuff seems inaccurate (for example the fraction of baryons locked into stars is tiny and will always remain tiny). If two brown dwarves collide (extremely unlikely, but if you wait long enough, anything with some tiny ...

3

There is no gravitational phenomenon associated with exact alignment. (moreover, exact alignment never happens, there is always a small deviation). The directions of tidal forces are aligned and hence sum-up for alignment, but this maximum is quite broad and nothing spectacular happens near exact alignment. You need close to exact alignment (depending on ...

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I personally found Stephen Hawking's "A Breif History of Time" to be very interesting and informative. It is a little bit advanced, but is put forward in plain English. Here is a link to it on Amazon, and you can "look inside" to see part of the book and see what you think. ...

1

Maybe a very old Neutron Star? A black dwarf would not emit any visible light, but the universe is not old enough for that. Even the oldest and coolest white dwarfs still have a temperature between 2500-4000K (sorry for not remembering the reference for this). Brown dwarfs (or planemos/sub-brown dwarfs) like WISE 0855–0714 could be as cool as ice. but they ...

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