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  2. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    The nearest star, Proxima Centauri, is about 1.3 parsecs (4.2 light-years) from the Sun: from that distance, the gap between the Earth and the Sun spans slightly less than one arcsecond. [2] Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand parsecs, and the Andromeda Galaxy ...

  3. List of nearest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_stars

    The easiest way to determine stellar distance to the Sun for objects at these distances is parallax, which measures how much stars appear to move against background objects over the course of Earth's orbit around the Sun. As a parsec (parallax-second) is defined by the distance of an object that would appear to move exactly one second of arc ...

  4. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    This is because the distance between Earth and the Sun is not fixed (it varies between 0.983 289 8912 and 1.016 710 3335 au) and, when Earth is closer to the Sun , the Sun's gravitational field is stronger and Earth is moving faster along its orbital path. As the metre is defined in terms of the second and the speed of light is constant for all ...

  5. Observable universe - Wikipedia

    en.wikipedia.org/wiki/Observable_universe

    The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light-years or 4.40 ...

  6. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    The largest unit for expressing distances across space at that time was the astronomical unit, equal to the radius of the Earth's orbit at 150 million kilometres (93 million miles). In those terms, trigonometric calculations based on 61 Cygni's parallax of 0.314 arcseconds, showed the distance to the star to be 660 000 astronomical units (9.9 ...

  7. List of nearest galaxies - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_galaxies

    This is a list of known galaxies within 3.8 megaparsecs (12.4 million light-years) of the Solar System, in ascending order of heliocentric distance, or the distance to the Sun. This encompasses about 50 major Local Group galaxies, and some that are members of neighboring galaxy groups , the M81 Group and the Centaurus A/M83 Group , and some ...

  8. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    parsec: 2.32061: light-seconds: ... 109 times the radius of the Earth, and 1/215th of an astronomical unit, the approximate distance between Earth and the Sun.

  9. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    Length of a meridian on Earth (distance between Earth's poles along the surface) [37] 40.075 Mm Length of Earth's equator: 10 8: 100 Mm: 142.984 Mm Diameter of Jupiter: 299.792 Mm Distance traveled by light in vacuum in one second (a light-second, exactly 299,792,458 m by definition of the speed of light) 384.4 Mm Moon's orbital distance from ...