Astrophysics (Index)About

astronomical unit

(AU)
(about 93 million miles)

An astronomical unit (AU) is a distance unit representing the distance between the Earth and the Sun, or more specifically the mean of the Earth's orbit's aphelion and perihelion. The International Astronomical Union (IAU) has defined a standard AU length of 149597870700 meters, which is considered a reasonable exact value (i.e., "nominal" value) approximating this distance. The AU is commonly used for distances within the solar system and other star systems, e.g., for orbital radii. An AU is:

Some distances in AU:

0.000085 AU Earth diameter
0.0026 AU distance from Earth to Moon
0.0093 AU diameter of the Sun
5.2 AU radius of Jupiter's orbit
30 AU radius of Neptune's orbit
276200 AU distance to Alpha Centauri
1.6 billion AU distance to galactic center
1.6 trillion AU distance to Andromeda

(distance,unit,Earth,Sun,astronomy)
Further reading:
https://en.wikipedia.org/wiki/Astronomical_unit
https://en.wiktionary.org/wiki/astronomical_unit
https://astronomy.swin.edu.au/cosmos/A/astronomical+unit
https://cneos.jpl.nasa.gov/glossary/au.html
https://www.iau.org/public/themes/measuring/
https://www.iau.org/static/resolutions/IAU2012_English.pdf
https://syrte.obspm.fr/IAU_resolutions/Sumredef_au.html

Referenced by pages:
10199 Chariklo
2010 TK7
51 Eridani b
51 Pegasi b (51 Peg b)
55 Cancri e (55 Cnc e)
67P/Churyumov-Gerasimenko (67P)
Achernar
astronomical quantities
Beta Centauri
Beta Pictoris b (β Pic b)
C/2014 UN271
Ceres
Comet Shoemaker-Levy 9
core collapse
dark star
direct imaging
DM Tau
Earth
escape velocity (Ve)
evaporating gas globule (EGG)
extra-solar planet
giant star
GJ 1132 b
GJ 1214 b
Gliese 436 b (GJ 436 b)
grand tack hypothesis
gravitational collapse
HAT-P-7b
Haumea
HD 189733 b
HD 209458 b
HD 80606 b
heliopause
heliosheath
heliosphere
Hills Cloud
hot Jupiter (HJ)
HR 8799
interplanetary medium (IPM)
J1407
Jupiter
K2-18b
Kepler-1625b
Kepler-16b
Kepler-186f
Kepler-452b
Kepler-79
Kuiper Belt (K Belt)
LHS 3844 b
light-year (ly)
Mars
Mars crosser (MC)
Mercury
NANOGrav
natural astronomical telescopes
Neptune
New Horizons (NF1)
occultation observations
OGLE-2005-BLG-390Lb
Oort Cloud
parallax
Parker Solar Probe (PSP)
parsec (pc)
Planet Nine
planetary migration
Pluto
Poynting-Robertson effect
protoplanetary disk (PPD)
Proxima b
Psyche
quasi-satellite
radial velocity (RV)
red giant
Rigel
Saturn
Scholz's Star
Schwarzschild radius (RS)
Sedna
snow line
solar constant
Solar Orbiter (SolO)
Spitzer Space Telescope (SST)
supergiant
TOI 700 d
trans-Neptune object (TNO)
TRAPPIST-1
Ulysses
Uranus
Venus
Voyager
VY Canis Majoris (VY CMa)
WASP-12b
WASP-33b
WASP-43b
WASP-67b
WD J0651+2844 (J0651)
wide binaries (WB)
XO-3b

Index