Monday, January 3 – Young Moon passes Venus and Mercury (after sunset)
For a brief period after sunset on Monday, January 3, the very young crescent Moon will be positioned near the inner planets Venus and Mercury, just above the southwestern horizon. Once the Sun has completely set, seek out the very bright speck of Venus, and then look a fist’s width to its left (or 11 degrees to the celestial southeast) for the sliver of the two-per-cent-illuminated Moon. Magnitude -0.7 Mercury will shine several finger widths above the Moon, allowing them to share the field of view in binoculars (green circle). The Moon and Venus will set first, leaving Mercury to brighten as the sky darkens. Observers at southerly latitudes will see the trio a little higher and in a darker sky.
Tuesday, January 4 – Earth at perihelion (at 07:00 GMT)
On Tuesday, January 4 at 07:00 GMT or 2 a.m. EST, the Earth will reach perihelion, its minimum distance from the Sun for the year. At that time Earth will sit 147.105 million kilometres from our star — or 1.66 per cent closer than our mean distance of 1.0 Astronomical Units. As winter-chilled Northern Hemisphere dwellers will attest, daily temperatures on Earth are not controlled by our proximity to the Sun, but by the number of hours of daylight we experience.
Tuesday, January 4 – Crescent Moon near Saturn (early evening)
The moon will make its monthly trip past the bright gas giant planets starting on Tuesday evening, January 4. Once the sky begins to darken after sunset, the creamy dot of Saturn will appear shining several finger widths to the upper right (or five degrees to the celestial southeast) of the slim crescent Moon, close enough for them to share the view in binoculars (green circle). Watch for the brighter planets Mercury (below them) and Jupiter (above them). The grouping will make a terrific photo opportunity.
Wednesday, January 5 – Waxing Moon with many Planets (early evening)
On Wednesday, January 5, the waxing crescent Moon will climb to sit a palm’s width below (or 6 degrees to the celestial southwest of) bright Jupiter in the southwestern sky after dusk. Saturn, Mercury and Venus will be strung out to their lower right – although Venus will set quickly after sunset. The line of planets will express the plane of our solar system, close to the ecliptic (green line), on the night sky. As the sky darkens, keep an eye out for Earthshine, sunlight reflected from Earth that slightly brightens the dark portion of the Moon’s disk.
Friday, January 7 – Mercury at greatest eastern elongation (after sunset)
On Friday morning, January 7 in the Americas, Mercury (orbit shown in red) will reach its widest separation of 19 degrees east of the Sun, and maximum visibility for the current apparition. That timing means that Mercury will appear almost as far from the Sun on both Thursday and Friday. With Mercury positioned just below the evening ecliptic (green line) in the southwestern sky, this appearance of the planet will be a relatively good one for both Northern and Southern Hemisphere observers. The optimal viewing times at mid-northern latitudes will be around 5:30 p.m. local time. Viewed in a telescope (inset) the planet will exhibit a waning, half-illuminated phase. The bright planets Jupiter and Saturn will share the scene.
Sunday, January 9 – First quarter Moon (at 18:11 UTC)
When the Moon completes the first quarter of its orbit around Earth at 1:11 p.m. EST (or 18:11 UTC) on Sunday, January 9, the relative positions of the Earth, Sun and Moon will cause us to see it half-illuminated on its eastern side. At first quarter, the Moon always rises around noon and sets around midnight, so it is also visible in the afternoon daytime sky. The evenings surrounding first quarter are the best for seeing the lunar terrain when it is dramatically lit by low-angled sunlight.
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.