How many light-day in 1 au? The answer is 0.005775518331437. We assume you are converting between light day and astronomical unit. You can view more details on each measurement unit: light-day or au The SI base unit for length is the metre. 1 metre is equal to 3.8606955462749E-14 light-day, or 6.6845871222684E-12 au. Note that rounding errors may occur, so always check the results. Use this page to learn how to convert between light days and astronomical units. Type in your own numbers in the form to convert the units!
1 light-day to au = 173.14463 au
2 light-day to au = 346.28927 au
3 light-day to au = 519.4339 au
4 light-day to au = 692.57853 au
5 light-day to au = 865.72316 au
6 light-day to au = 1038.8678 au
7 light-day to au = 1212.01243 au
8 light-day to au = 1385.15706 au
9 light-day to au = 1558.30169 au
10 light-day to au = 1731.44633 au
You can do the reverse unit conversion from au to light-day, or enter any two units below:
A light day (also written light-day) is a unit of length. It is defined as the distance light travels in an absolute vacuum in one day (of 86,400 seconds) or 25,902,068,371,200 metres (~26 Tm).
Note that this value is exact, since the metre is actually defined in terms of the speed of light. The light day isn't very frequently used at all since there are few astronomical objects or distances of that magnitude; the Oort cloud, for example, is thought to extend between 290 and 580 light-days out from the Sun.
The astronomical unit (AU or au or a.u. or sometimes ua) is a unit of length defined to be exactly equal to 149,597,870,700 metres. Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition.
The symbol "ua" is recommended by the Bureau International des Poids et Mesures, but in the United States and other anglophone countries the reverse usage is more common. The International Astronomical Union recommends "au" and international standard ISO 31-1 uses "AU".
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