The latter convention was adopted on and after 1 January 1925 for astronomical purposes, resulting in a discontinuity of 12 hours, or half a day earlier.

It has also been suggested that the site may have been used for astronomical purposes (Morieson 2003).

For astronomical purposes, before 1925 a day was considered to start at noon rather than the previous midnight.

These purported alignments have been taken as evidence of some astronomical purpose in cairn placement and construction.

Since prehistory, they have also been built as sepulchral monuments, or used for defensive, hunting, ceremonial, astronomical and other purposes.

They had nothing to do with the original astronomical purpose.

Galileo greatly improved upon these designs the following year and is generally credited with being the first to use a telescope for astronomical purposes.

He also appears to be the first to make use of the compass for astronomical purposes.

Natural ridges, hills, and human made mounds were also used for astronomical and burial purposes.

For astronomical purposes, these walls were oriented so they lie precisely on a meridian.