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3.261 56 ly. The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles). [a] The parsec unit is obtained by the use of parallax and trigonometry ...
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 used to measure distances beyond the scope of the Solar System and is about 3.26 light-years: 1 pc = 1 au/tan(1″) [6] [61] Proxima Centauri: 268,000 ...
A light-year, alternatively spelled light year (ly or lyr[3]), is a unit of length used to express astronomical distances and is equal to exactly 9,460,730,472,580.8 km (Scientific notation: 9.4607304725808 × 10 12 km), which is approximately 5.88 trillion mi.
Stellar parallax is most often measured using annual parallax, defined as the difference in position of a star as seen from Earth and Sun, i.e. the angle subtended at a star by the mean radius of Earth's orbit around the Sun. The parsec (3.26 light-years) is defined as the distance for which the annual parallax is 1 arcsecond.
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 ...
This number is likely much higher, due to the sheer number of stars needed to be surveyed; a star approaching the Solar System 10 million years ago, moving at a typical Sun-relative 20–200 kilometers per second, would be 600–6,000 light-years from the Sun at present day, with millions of stars closer to the Sun.
So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then the distance would have been only about 42 million light-years at the time of decoupling. The light-travel distance to the edge of the observable universe is the age of the universe times the speed of light, 13.8 billion light ...
A parsec is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond (not to scale). The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles).