SkyEye

The Calendar

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

Sun Ophiuchus → Sagittarius

Although Ophiuchus is not a member of the zodiac, the ecliptic passes through it.

Mercury Ophiuchus → Sagittarius

After being occulted by the Sun last month, Mercury appears low in the southwest at sunset. It rises higher above the horizon as it heads towards greatest elongation east on 29 December.

Venus Virgo → Libra

The morning star has put on a wonderful show for northern hemisphere observers but now Venus declines in altitude. From the south, however, the opposite is true and the bright planet climbs higher in the dawn sky. By the end of the month the morning star is seen equally well from both hemispheres.

C/2013 US10 Catalina Virgo → Boötes

An Oort cloud denizen, comet C/2013 US10 Catalina is making its first and only pass through the inner solar system and passed perihelion last month. Discovered in 2013 by the Catalina Sky Survey, it has an inclination of 149° and a perihelion distance of just over 0.8 AU. It may reach sixth or even fifth magnitude for the next month or two. It was best placed for viewing from the southern hemisphere but observers in northern latitudes will get their chance from this month onwards as the comet races high into the northern skies.

Mars Virgo

The red planet now rises in the early morning hours, well before the Sun.

Jupiter Leo

Quadrature is an excellent time to observe the gas giants as the interplay of shadows between the planets and their satellites is at its most pronounced. Jupiter reaches west quadrature on the 14 December and is rising before midnight.

Saturn Ophiuchus

At conjunction last month, the ringed planet reappears in the dawn sky just ahead of the Sun by the end of December.

Uranus Pisces

This faint planet, the most distant object in the solar system visible to the naked eye, sets around midnight. It is occulted by the Moon 20 December.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system but you will need to look for it in the early evening as it sets well before midnight.