* Astronomy

Blobrana · L

RE: Astronomical unit

Blobrana · L

International Astronomical Union RESOLUTION B2 on the re-definition of the astronomical unit of length.

that the value of the astronomical unit compatible with Barycentric Dynamical Time (TDB) in Table 1 of the IAU 2009 System (149 597 870 700 m ±3 m), is an average (Pitjeva and Standish 2009) of recent estimates for the astronomical unit defined by k,
recommends that the astronomical unit be re-defined to be a conventional unit of length equal to 149 597 870 700 m exactly, as adopted in IAU 2009 Resolution B2
Read more (PDF)

Blobrana · L

Astronomical distance units -parsecs, light years and AU

Click to Play | View Details

Blobrana · L

Appearances aside, the stars are not eternal and the planets do not move with clockwork precision. For these reasons, one astronomer is proposing that his colleagues ditch the astronomical unit, or AU, as the standard measure of distance within the solar system.
One AU is roughly the average distance between the Sun and the Earth, or 149,597,870.691 kilometres. But its formal definition by the International Astronomical Union (IAU) is rather more complicated.

Read more