<P> Determining an accurate distance to Polaris is important for the cosmic distance ladder because, until new data comes, it is the only Cepheid variable for which precision distance data exists, which has a ripple effect on distance measurements that use this "ruler". </P> <P> Polaris in stellar catalogues and atlases </P> <Table> <Tr> <Td> <Table> <Tr> <Th> Source </Th> <Th> Presence </Th> </Tr> <Tr> <Td> Ptolemy (~ 169) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Al - Sufi (964) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Al - Biruni (~ 1030) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Khayyam (~ 1100) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Al - Tusi (1272) </Td> <Td> No </Td> </Tr> <Tr> <Td> Ulugh Beg (1437) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Copernicus (1543) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Schöner (1551) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Brahe (1598) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Brahe (1602) </Td> <Td> Yes </Td> </Tr> </Table> </Td> <Td> <Table> <Tr> <Th> Source </Th> <Th> Presence </Th> </Tr> <Tr> <Td> Bayer (1603) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> De Houtman (1603) </Td> <Td> No </Td> </Tr> <Tr> <Td> Kepler (1627) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Schiller (1627) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Halley (1679) </Td> <Td> No </Td> </Tr> <Tr> <Td> Hevelius (1690) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Flamsteed (1725) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Flamsteed (1729) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Bode (1801a) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Bode (1801b) </Td> <Td> Yes </Td> </Tr> </Table> </Td> </Tr> </Table> <Tr> <Td> <Table> <Tr> <Th> Source </Th> <Th> Presence </Th> </Tr> <Tr> <Td> Ptolemy (~ 169) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Al - Sufi (964) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Al - Biruni (~ 1030) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Khayyam (~ 1100) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Al - Tusi (1272) </Td> <Td> No </Td> </Tr> <Tr> <Td> Ulugh Beg (1437) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Copernicus (1543) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Schöner (1551) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Brahe (1598) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Brahe (1602) </Td> <Td> Yes </Td> </Tr> </Table> </Td> <Td> <Table> <Tr> <Th> Source </Th> <Th> Presence </Th> </Tr> <Tr> <Td> Bayer (1603) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> De Houtman (1603) </Td> <Td> No </Td> </Tr> <Tr> <Td> Kepler (1627) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Schiller (1627) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Halley (1679) </Td> <Td> No </Td> </Tr> <Tr> <Td> Hevelius (1690) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Flamsteed (1725) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Flamsteed (1729) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Bode (1801a) </Td> <Td> Yes </Td> </Tr> <Tr> <Td> Bode (1801b) </Td> <Td> Yes </Td> </Tr> </Table> </Td> </Tr>

How far is the northern star from earth