Solar apex

The solar apex, or the Apex of the Sun's Way, refers to the direction that the Sun travels with respect to the Local Standard of Rest. This is not to be confused with the Sun's apparent motion through the constellations of the zodiac, which is illusory – this supposed motion is actually caused by the Earth revolving around the Sun.

The general direction of the solar apex is southwest of the star Vega near the constellation of Hercules. There are several coordinates for the solar apex. The visual coordinates (as obtained by visual observation of the apparent motion) is right ascension (RA) 18^h 28^m 0^s and declination (dec) of 30° North (in galactic coordinates: 56.24° longitude, 22.54° latitude). The radioastronomical position is RA 18^h 03^m 50.2^s and dec 30° 00′ 16.8″ (galactic coordinates: 58.87° longitude, 17.72° latitude).

The speed of the Sun towards the solar apex is about 16.5 km/s. This speed is not to be confused with the orbital speed of the Sun around the Galactic center, which is about 220 km/s and is included in the movement of the Local Standard of Rest. The sun's motion in the Milky Way is also more complex than might be immediately supposed^[1].

The nature and extent of the solar motion was first demonstrated by William Herschel in 1783.

The solar antapex, the direction opposite of the solar apex, is located near the star Zeta Canis Minoris.

References

1. ^ Priscilla Frisch (2000). "The Galactic Environment of the Sun", American Scientist.