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How do we know how far away objects are in space, and what units of measurements are used in astronomy for determining these distances?
18 maj 2020 · Astronomical units are a useful measure for distances in our solar system, while light years are more practical for distances to the stars. The nearest star system, Alpha Centauri, is seen from Saturn in this image from NASA’s Cassini spacecraft.
11 maj 2018 · The units of measurement we use to define distances on Earth prove inadequate to the task of reckoning distances in outer space. Standard astronomical measures include the astronomical unit and the parsec, with another unit, the light-year, is common in popular usage.
To measure the distances between stars, astronomers often use light-years (abbreviated ly). A light-year is the distance that light travels in a vacuum in one year: 1 ly = 9.5 x 10 12 km = 63,240 AU. Proxima Centauri is the nearest star to Earth (other than the Sun) and is 4.2 light-years away.
au. Astronomical Unit, a measure of distance, based on the mean Sun-Earth distance. The International Astronomical Union defines the AU as the distance from the Sun at which a particle of negligible mass, in an unperturbed orbit, would have an orbital period of 365.2568983 days (a Gaussian year).
The most common measurement unit for astronomical distances is the light-year. The name often confuses people—remember that a light-year is a measurement of length/distance, not time. It means the distance that a photon of light can travel through the vacuum of space in one Earth year.
18 maj 2020 · Astronomical units, abbreviated AU, are a useful unit of measure within our solar system. One AU is the distance from the Sun to Earth's orbit, which is about 93 million miles (150 million kilometers).
