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  2. Expansion of the universe - Wikipedia

    en.wikipedia.org/wiki/Expansion_of_the_universe

    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 ...

  3. Future of Earth - Wikipedia

    en.wikipedia.org/wiki/Future_of_Earth

    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)).

  4. On the Sizes and Distances (Aristarchus) - Wikipedia

    en.wikipedia.org/wiki/On_the_Sizes_and_Distances...

    This means that the Sun is (a mean of) 6 + 3 ⁄ 4 times wider than the Earth, or that the Sun is 13 + 1 ⁄ 2 Earth-radii wide. The Moon and Sun must then be 20 + 1 ⁄ 4 and 387 Earth-radii away from us in order to subtend an angular size of 2º.

  5. Formation and evolution of the Solar System - Wikipedia

    en.wikipedia.org/wiki/Formation_and_evolution_of...

    When the Sun leaves the red-giant branch and enters the asymptotic giant branch, the habitable zone will abruptly shrink to roughly the space between Jupiter and Saturn's present-day orbits, but toward the end of the 200 million-year duration of the asymptotic giant phase, it will expand outward to about the same distance as before. [128]

  6. Sun - Wikipedia

    en.wikipedia.org/wiki/Sun

    The Sun orbits the Galactic Center at a distance of 24,000 to 28,000 light-years. From Earth, it is 1 astronomical unit (1.496 × 10 8 km) or about 8 light-minutes away. Its diameter is about 1,391,400 km (864,600 mi), 109 times that of Earth. Its mass is about 330,000 times that of Earth, making up about 99.86% of the total mass of the Solar ...

  7. Earth's orbit - Wikipedia

    en.wikipedia.org/wiki/Earth's_orbit

    Earth orbit (yellow) compared to a circle (gray) Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi), or 8.317 light-minutes, [1] in a counterclockwise direction as viewed from above the Northern Hemisphere. One complete orbit takes 365.256 days (1 sidereal year), during which time Earth has traveled 940 million ...

  8. Red giant - Wikipedia

    en.wikipedia.org/wiki/Red_giant

    Red-giant-branch stars have luminosities up to nearly three thousand times that of the Sun (L ☉), spectral types of K or M, have surface temperatures of 3,000–4,000 K, and radii up to about 200 times the Sun (R ☉). Stars on the horizontal branch are hotter, with only a small range of luminosities around 75 L ☉. Asymptotic-giant-branch ...

  9. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun 's photosphere where the optical depth equals 2/3: [1] 695,700 kilometres (432,300 miles) is approximately 10 times the average radius of Jupiter, 109 times the radius ...