The Planet Wheel is a guide to the visibility of the planets in the sky. It shows the positions of the planets and the Moon, relative to the Sun.
The nearer a planet is to the Sun in the sky, the less visible it becomes, and planets that are very close to the Sun in the sky are only above the horizon during the day, and so cannot be observed at all. So, planets shown in brighter part of the Wheel, near the Sun, are hard or impossible to see. Conversely, planets opposite the Sun on the Wheel are above the horizon for most of the night.
Planets in the regions marked 'Sunrise' and 'Sunset' might be visible at those times, while those in the 'Morning' and 'Evening' zones will be more visible during those periods. The details of a particular planet's visibility will depend on the observer's exact position on the Earth's surface.
Because the Moon travels through the sky much more quickly than the other bodies shown here, it is shown twice on the Wheel, to illustrate its position at the beginning of the period shown, and at the end. In each case, the Moon's phase is indicated.
Everything shown on the Planet Wheel is 'clickable' - if you want more information about a body or a constellation, just click it or its label to open the relevant page within the site.
The Wheel is scaled according to Right Ascension, with the First Point of Aries at the top. This means that the Sun appears at the top of the Wheel during the Vernal Equinox, and at the bottom during the Autumnal Equinox. The Sun will pass the 6h00 mark (the extreme left of the Wheel) at the Summer Solstice, and the 18h00 mark (the extreme right) at the Winter Solstice.
The constellation names shown around the outside of the Wheel correspond to actual constellations in the sky. The Sun's journey across the sky is not evenly divided between these constellations - it takes far longer to cross Virgo, say, than Scorpius (whose name is abbreviated to 'Sco' above). The current alignment of the Ecliptic means that it also passes through Ophiuchus, and this constellation is also shown on the Wheel (between Sagittarius and Scorpius).