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The most distant space probe, Voyager 1, was about 18 light-hours (130 au,19.4 billion km, 12.1 billion mi) away from the Earth as of October 2014. [29] It will take about 17 500 years to reach one light-year at its current speed of about 17 km/s (38 000 mph, 61 200 km/h) relative to the Sun.
The Hubble length or Hubble distance is a unit of distance in cosmology, defined as cH −1 — the speed of light multiplied by the Hubble time. It is equivalent to 4,420 million parsecs or 14.4 billion light years. (The numerical value of the Hubble length in light years is, by definition, equal to that of the Hubble time in years.)
Distance light travels in one day — Light-year: 63 241 — Distance light travels in one Julian year (365.25 days) — Oort cloud: 75 000: ± 25 000: Distance of the outer limit of Oort cloud from the Sun (estimated, corresponds to 1.2 light-years) — Parsec: 206 265 — One parsec. The parsec is defined in terms of the astronomical unit, is ...
380 Earth radii (very inaccurate, true=16000 Earth radii) Aristarchus of Samos made a measurement of the distance of the Sun from the Earth in relation to the distance of the Moon from the Earth. The distance to the Moon was described in Earth radii (20, also inaccurate). The diameter of the Earth had been calculated previously.
The amount of shift is quite small, even for the nearest stars, measuring 1 arcsecond for an object at 1 parsec's distance (3.26 light-years), and thereafter decreasing in angular amount as the distance increases. Astronomers usually express distances in units of parsecs (parallax arcseconds); light-years are used in popular media.
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The planet is about the size of Venus, so slightly smaller than Earth, and may be temperate enough to support life, the researchers said. Dubbed Gliese 12 b, the planet takes 12.8 days to orbit a ...
[a] The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 AU subtends an angle of one arcsecond [1] ( 1 / 3600 of a degree). 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 ...