around . The larger distance derives from the assumption of a very bright absolute magnitude for Canopus. Hipparcos established Canopus as being () from the Solar System; this is based on its 2007 parallax measurement of . At 95 parsecs, the interstellar extinction for Canopus is low at 0.26 magnitudes. Canopus is too bright to be included in the normal observation runs of the Gaia satellite and there is no published Gaia parallax for it. At present the star is drifting further away from the Sun with a radial velocity of 20 km/s. Some 3.1 million years ago it made the closest approach to the Sun at a distance of about . Canopus is orbiting the Milky Way with a heliocentric velocity of 24.5 km/s and a low eccentricity of 0.065. Physical characteristics The absorption lines in the spectrum of Canopus shift slightly with a period of . This was first detected in 1906 and the Doppler variations were interpreted as orbital motion. An orbit was even calculated, but no such companion exists and the small radial velocity changes are due to movements in the atmosphere of the star. The maximum observed radial velocities are only 0.7 to . Canopus also has a magnetic field that varies with the same period, detected by the Zeeman splitting of its spectral lines. Canopus is bright at microwave wavelengths, one of the few F-class stars to be detected by radio. The rotation period of the star is not accurately known, but may be over three hundred days. The projected rotational velocity has been measured at 9 km/s. An early interferometric measurement of its angular diameter in 1968 gave a limb-darkened value of , close to the accepted modern value. Very-long-baseline interferometry has been used to calculate Canopus' angular diameter at . Combined with distance calculated from its Hipparcos parallax, this gives it a radius of 71 times that of the Sun. If it were at the centre of the Solar System, it would extend 90% of the way to the orbit of Mercury. The radius and temperature relative to the Sun means that it is 10,700 times more luminous than the Sun, and its position in the H-R diagram relative to theoretical evolutionary tracks means that it is times as massive as the Sun. Measurements of its shape find a 1.1° departure from spherical symmetry. Canopus is a source of X-rays, which are