The moon in December’s early days is waning toward an occultation Dec. 2 and new phase Dec. 4. The occultation is for viewers in the Eastern Hemisphere. For westerners, it’s a close graze with Mars in the eastern morning sky 0.7 degrees south of Luna. New moon is eclipse season, following six months after the eclipses in May and June. The lunar eclipse last month (14 days earlier) is followed by a total solar eclipse Dec. 4. Unfortunately, the eclipse is only visible to viewers in Antarctica or the Falkland Islands. Venus, Dec. 6, is 1.9 degrees north of the moon; Saturn Dec. 7 is four degrees north; Jupiter Dec. 9 is also four degrees north. Dec. 10, the minor planet Pallas is half a degree south of the moon – an occultation in the Middle East. Uranus Dec. 15 is a little over a degree north.
Mercury is behind the sun for most of December, appearing at sundown in the west around Christmas Day. Both Mercury and Venus may be seen at western sundown, just a few degrees apart Dec. 29.
Venus is at greatest illuminated extent (GIE) Dec. 3. Even though the bright planet presents a smallish crescent shape, in square degrees and apparent size, the part illuminated by the sun is the greatest it can be and the planet is at its brightest.
Mars is occulted Dec. 2, but only for viewers in the Eastern Hemisphere. For North American people, Mars and the moon are less than a degree apart on that day; and again, Dec. 31, Mars is 0.5 degrees north of the moon. Dec. 26, Mars is five degrees north of its “rival,” Antares, but only half as bright as the giant carbon star.
Jupiter is in the west at sundown, close to the horizon – a difficult target for some. The moon is nearby Dec. 8and 9.
Saturn can be a tough find in the winter twilight, setting shortly after the sun.
Uranus crosses the sky throughout the night, setting before sunrise.
Neptune is high in the west as twilight approaches. If one is prepared right after sunset, he or she may see six planets – Venus and Mercury, Saturn, Jupiter, Neptune and Uranus. A telescope is needed to spot Neptune.
Winter solstice occurs on Dec. 21 at 15:59 UT.
James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000, was national president for two terms, is now the editor of Observer’s Handbook, and production manager of the bi-monthly RASC Journal. The IAU named asteroid 1995 XC5 “(22421) Jamesedgar” in his honour and he was recently awarded a Fellowship of the RASC.