Parsec pc
About the Parsec
A parsec is the distance at which one astronomical unit subtends an angle of one arcsecond, making it 648,000/π au, about 206,265 au, 3.26 light-years or 3.0857 × 10¹⁶ metres. The name combines parallax and second. The nearest star beyond the Sun, Proxima Centauri, is about 1.3 parsecs away.
Related Units
Astronomical unit
au149,597,870,700 m (exact)
The astronomical unit is roughly the mean distance from the Earth to the Sun. Since the IAU's 2012 Resolution B2 it is...
Light-year
ly9,460,730,472,580,800 m (exact)
A light-year is the distance light travels in vacuum in one Julian year of 365.25 days, which works out at exactly...
Metre
mBase unit; c = 299,792,458 m/s exactly
The metre is the length of the path travelled by light in vacuum in 1/299,792,458 of a second. It was first defined by...
Ångström
Å1 Å = 10⁻¹⁰ m = 0.1 nm (exact)
The ångström equals one ten-billionth of a metre, roughly the size of an atom. It is named after the Swedish physicist...