Every week, SkyNews publishes a list of key events in the Canadian sky in This Week’s Sky. This series gives you all the latest news in Solar System movements, including where the planets are in our sky and Moon phases. From eclipses to meteor showers, This Week’s Sky keeps you updated on the best in upcoming astronomical highlights.
Monday, December 26 – Crescent Moon and Saturn (evening)
Two days after its visit with the inner planets, the young crescent Moon will shine prettily beside Saturn in the southwestern sky, with the tail stars of Capricornus, the Sea-Goat, twinkling between them.
After dusk on Monday, December 26, the yellowish ringed planet will be positioned several finger widths to the upper right (or five degrees to the celestial northwest) of the Moon — close enough for them to share the view in binoculars (green circle). By the time the duo drops below the west-southwestern horizon shortly after 8 p.m. local time, the Moon will have shifted to Saturn’s left.
Observers who look immediately after sunset can catch the inner planets Mercury and Venus to their lower right before they set.
Tuesday, December 27 – The entire Solar System (after sunset)
On the evenings surrounding Tuesday, December 27, observers at mid-northern latitudes with unobstructed views to the southwest can observe the waxing crescent Moon and all of the planets.
After the sun sets, the inner planets Venus and Mercury will shine just above the southwestern horizon. The Moon and the rest of the major planets in the Solar System will stretch across the southern sky — tracing out the plane of our Solar System. From celestial west to east, the line will extend from yellowish Saturn, past the crescent Moon, Neptune, bright Jupiter, and Uranus, and end at bright reddish Mars.
Neptune and Uranus will be easier to see in a darker sky after Mercury and Venus set.
Wednesday, December 28 – Venus swings past Mercury (after sunset)
Starting about 20 minutes after the Sun has completely set on Wednesday, December 28, search above the southwestern horizon for the planets Venus and Mercury. They will appear in a close conjunction, only a thumb’s width apart, with 41 times brighter Venus positioned below Mercury. On the following evening, the planets’ relative orbital motion (red paths with labelled dates at 5 p.m.) will shift Venus higher to Mercury’s left. They will draw farther apart each evening as Venus climbs away from the Sun while Mercury sinks sunward.
Wednesday, December 28 – Waxing Moon meets Neptune and Jupiter (evening)
In the southwestern sky on Wednesday evening, December 28, the waxing crescent Moon will shine near very bright Jupiter and the faint speck of distant Neptune. Magnitude -2.39 Jupiter will be positioned a generous palm’s width to the Moon’s upper left, or approximately eight degrees to the celestial northeast. Neptune will be located several degrees to the Moon’s upper right (celestial north).
The 38 per cent illuminated Moon’s light will make seeing magnitude 7.9 Neptune harder — but good binoculars (green circle) and backyard telescopes can reveal the blue planet if you hide the Moon outside of your field of view.
Thursday, December 29 – Half Moon glides past Jupiter (evening)
Skywatchers who missed seeing the crescent Moon posing below Jupiter on Wednesday, will have a second opportunity to catch the Moon shining near bright Jupiter in the southwestern sky on Thursday evening — December 29. For observers in easterly time zones, the Moon and Jupiter will be just cosy enough to share the view in binoculars (green circle). Those viewing from farther west will see them more widely separated. As the Moon and Jupiter sink towards the horizon in late evening, the diurnal rotation of the sky will lift the Moon above the planet.
Friday, December 30 – First quarter Moon (at 01:20 GMT)
The Moon will complete the first quarter of its monthly journey around Earth at 01:20 GMT on Friday, December 30, which translates to 8:20 p.m. EST and 5:20 p.m. PST on Thursday, December 29.
During this first quarter, the Moon’s 90-degree angle from the Sun will cause us to see Luna exactly half-illuminated on its eastern side. At first quarter, the Moon always rises around midday and sets around midnight, so it is also visible in the afternoon daytime sky. The evenings around the first quarter are the best ones for viewing the lunar terrain while it is dramatically lit by low-angle sunlight, especially along the terminator — the pole-to-pole boundary separating its lit and dark hemispheres.
Friday, December 30 – Two shadows cross Jupiter (7:27 to 8:15 p.m. JST)
From time to time, observers with good telescopes can watch the small, round/black shadows of the Galilean moons traverse Jupiter’s disk. On Friday evening, December 30, sky-watchers located in eastern Asia, Southeast Asia, and Australia/New Zealand can watch two shadows crossing the southern hemisphere of Jupiter at the same time — for about 45 minutes.
At 7:27 p.m. Japan Standard Time or 10:27 GMT, the small shadow of Io will join the larger shadow of Ganymede, which began its own crossing of the planet 90 minutes earlier. Ganymede’s shadow will leave Jupiter at 8:15 p.m. JST or 11:15 GMT, leaving Io’s shadow to continue on alone until 9:34 p.m. JST (or 12:34 GMT).
Saturday, December 31 – Welcome to the Winter Football (all night)
The Winter Football, also known as the Winter Hexagon and Winter Circle, is an asterism composed of the brightest stars in the constellations of Canis Major, Orion, Taurus, Auriga, Gemini, and Canis Minor – specifically Sirius, Rigel, Aldebaran, Capella, Castor & Pollux, and Procyon. All of those stars will have cleared the horizon in the southeastern sky by 7 p.m. local time on Saturday, December 31. When it stands upright in the south towards midnight, the great pattern will encompass an area of the sky 45 degrees wide and 66 degrees high. The Milky Way passes vertically through the asterism, which is visible during evening from mid-November to spring every year.
Sunday, January 1 – Bright Moon near Uranus (evening)
On Sunday, January 1, the waxing gibbous Moon will rise after midday and then linger into the night
sky until well beyond midnight. For observers in the Americas, the Moon will have just completed an
occultation of the magnitude 5.7 planet Uranus.
Once the sky darkens in the Eastern time Zone, look for Uranus shining less than a lunar diameter to the Moon’s right (or celestial west), allowing the Moon and the planet to share the field of view in binoculars and backyard telescopes (green circle).
In more westerly time zones, Uranus will be three to four lunar diameters from the Moon. Observers in the
Canadian Maritimes and eastward across Greenland, Iceland, most of northern Europe, and most of
northern and western Russia can observe the occultation starting around 21:00 GMT.
Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the Universe together.