astronomical unit


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Related to astronomical unit: parsec

astronomical unit

(AU), mean distance between the earth and sun; one AU is c.92,960,000 mi (149,604,970 km). The astronomical unit is the principal unit of measurement within the solar system, e.g., Mercury is just over 1-3 AU and Pluto is about 39 AU from the sun.

astronomical unit

(AU or au) A unit of length that is used for distances, especially within the Solar System. It is effectively the mean distance between Earth and Sun. It is defined formally in terms of Kepler's third law and the Gaussian gravitational constant. One astronomical unit is equal to 149 597 870 kilometers or 499.005 light-seconds.

astronomical unit

[‚as·trə′näm·ə·kəl ′yü·nət]
(astronomy)
Abbreviated AU.
A measure for distance within the solar system equal to the mean distance between earth and sun, that is, about 92,956,000 miles (149,598,000 kilometers).
The semimajor axis of the elliptical orbit of earth.

astronomical unit

a unit of distance used in astronomy equal to the mean distance between the earth and the sun. 1 astronomical unit is equivalent to 1.495 × 1011 metres or about 9.3 × 107 miles
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References in periodicals archive ?
"We would not yet have detected the Earth," says Jewitt, "if it were more than 600 astronomical units from the sun." And that's assuming researchers knew where to look.
Shadow planet: strange orbits in the Kuiper belt revive talk of a Planet X in the solar system
The asteroid will only be about 0.01185 astronomical units or around 1.1 million miles away from the planet's center during its approach.
NASA Asteroid Tracker: Two Tiny NEOs Approaching Earth Friday
As it moves past Earth, its closest distance to the planet will be at 0.00688 astronomical units or around 640,000 miles away.
Two Large Asteroids To Zip Past Earth On Wednesday
During this time, the asteroid approached the planet from a distance of about 0.37388 astronomical units or around 35 million miles away.
3,240-Foot City-Killer Asteroid Headed For Earth This October
During this time, the asteroid will be about 0.04963 astronomical units or roughly 4.6 million miles from the Earth's center.
NASA Detects 3 Mega Asteroids Headed For Earth This August
During its approach, the asteroid will only be about 0.02809 astronomical units or roughly 2.6 million miles from the planet's center.
Two Small Asteroids Get Very Close To Earth This Weekend
A bull's-eye disk of dust and gas surrounds the young star HL Tauri, with ringlike gaps 15, 30, and 70 astronomical units from the star.
Planets hiding around HL Tauri?
The newly discovered object lies an estimated 43 astronomical units from the sun--43 times the Earth-sun distance--and appears to have the largest intrinsic brightness of any Kuiper belt resident, researchers report in a July 5 circular of the International Astronomical Union.
A new giant in the Kuiper belt
During its approach, the asteroid will only be about 0.02245 astronomical units or roughly 2 million miles from the Earth's center.
328-Foot Asteroid To Zip Past Earth On Friday
This object lies 43.3 astronomical units (6.49 billion km) from the Sun and is incredibly dim, 25.6 in magnitude.
Next target for new horizons
The camera revealed that the dust is confined to a region around the star no larger than 6.1 astronomical units (AU) in radius and could lie as close as 2.5 AU.
Nearby star may have its own asteroid belt
During this time, the asteroid flew at a distance of 0.10267 astronomical units or roughly 9.5 million miles from the planet.
820-Foot Hazardous Asteroid Will Fly By Earth On Monday

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