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The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. [1] It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it. To any observer in the universe, it appears that all but the nearest galaxies ...
It is expected that between 10 11 (100 billion) and 10 12 (1 trillion) years from now, their orbits will decay and the entire Local Group will merge into one large galaxy. [ 5 ] Assuming that dark energy continues to make the universe expand at an accelerating rate, in about 150 billion years all galaxies outside the Local Supercluster will ...
The Sun will experience more rapid mass loss, with about 33% of its total mass shed with the solar wind. The loss of mass will mean that the orbits of the planets will expand. The orbital distance of Earth will increase to at most 150% of its current value (that is, 1.5 AU (220 million km; 140 million mi)).
Assuming the Jovian orbit of 5.5 AU as the star radius, the inner shell would extend roughly 50 to 150 stellar radii (~300 to 800 AU) with the outer one as far as 250 stellar radii (~ 1,400 AU). The Sun's heliopause is estimated at 100 AU, so the size of this outer shell would be almost fourteen times the size of the Solar System.
(The numerical value of the Hubble length in light years is, by definition, equal to that of the Hubble time in years.) The Hubble distance would be the distance between the Earth and the galaxies which are currently receding from us at the speed of light, as can be seen by substituting D = cH −1 into the equation for Hubble's law, v = H 0 D.
For a time, Muslim astronomers accepted the Ptolemaic system and the geocentric model, which were used by al-Battani to show that the distance between the Sun and the Earth varies. [39] [40] In the 10th century, al-Sijzi accepted that the Earth rotates around its axis.
Scale factor (cosmology) The expansion of the universe is parametrized by a dimensionless scale factor . Also known as the cosmic scale factor or sometimes the Robertson–Walker scale factor, [1] this is a key parameter of the Friedmann equations. In the early stages of the Big Bang, most of the energy was in the form of radiation, and that ...
The distance the light from the edge of the observable universe has traveled is very close to the age of the universe times the speed of light, 13.8 billion light-years (4.2 × 10 ^ 9 pc), but this does not represent the distance at any given time because the edge of the observable universe and the Earth have since moved further apart. [53]