<Dd> ε = 23 ° 26 ′ 21.406" − 7001468367689999999 ♠ 46.836 769" T − 6996183100000000000 ♠ 0.000 1831" T + 6997200339999999999 ♠ 0.002 003 40" T − 5.76" × 10 T − 4.34" × 10 T </Dd> <P> These expressions for the obliquity are intended for high precision over a relatively short time span, perhaps ± several centuries . J. Laskar computed an expression to order T good to 0.02" over 1000 years and several arcseconds over 10,000 years . </P> <Dl> <Dd> ε = 23 ° 26 ′ 21.448" − 4680.93" t − 1.55" t + 1999.25" t − 51.38" t − 249.67" t − 39.05" t + 7.12" t + 27.87" t + 5.79" t + 2.45" t </Dd> </Dl> <Dd> ε = 23 ° 26 ′ 21.448" − 4680.93" t − 1.55" t + 1999.25" t − 51.38" t − 249.67" t − 39.05" t + 7.12" t + 27.87" t + 5.79" t + 2.45" t </Dd>

Earth's axis is tilted 10 degrees from a perpendicular to the plane of the ecliptic