OT Irish history for the modern attention span

In article
,
wrote:

Peter Cole wrote:
Micron, a micrometre, a unit of length in the metric system: one
millionth of a metre


Up until 1968. See the official SI website:
http://www.bipm.org/en/si/si_brochur...rminology.html

No coaching.

--
Michael Press

In article
,
Brian Huntley wrote:

On Feb 18, 11:06*pm, Michael Press wrote:

What are microns?

Like a parsec, only smaller.

How is a micron different from a parsec?

No coaching, Ben.

--
Michael Press

In article ,
Michael Press wrote:

In article
,
Brian Huntley wrote:

On Feb 18, 11:06*pm, Michael Press wrote:

What are microns?

Like a parsec, only smaller.

How is a micron different from a parsec?

A parsec is the distance at which one astronomical unit
subtends one second of arc. It was invented because the
parallax to stars could be measured to more decimal
places than the astronomical unit could be measured in
meters (or microns). When we put robots into solar orbit
we were finally able to get a good measure of the
astronomical unit in meters, and therefore an accurate
figure for the parsec in meters.

--
Michael Press