The “Battle of the Planets” in the evening sky will highlight the start of a historic year ahead for planetary observers with several bright planets vying for attention during the first half of the year and at least one bright planet on any given evening during the second half of the year. There will be many celestial delights to behold, which include a rare transit of Venus across the Sun, a slight partial eclipse of the Sun, close planetary groupings with each other and the Moon, meteor showers, orbiting satellites, and possibly a few nice comets and an unexpected aurora or two. The potentially best and most memorable event for 2012 will be the transit of Venus across the Sun on June 5 if the weather cooperates. If not, the next chance will not be until December 10, 2117, so hope for the best and make the most of it!
There are no lunar eclipses locally this year with the next total lunar eclipse not until April 15, 2014. There is a very slight partial solar eclipse on May 20, 2012, just minutes before sunset when the Sun will hardly be 1% eclipsed at best according to the Google Earth Interactive Solar Eclipse Simulator. The best places to see it locally would be on the shores of Oneida Lake and Lake Ontario.
In the evening sky Mars competes with Jupiter for attention during the beginning of 2012 and will be at its brightest in two years by March. Both will then have to compete with Saturn towards April, but Jupiter will be fading into the evening twilight by then. Mercury will beg for attention from late February into early March with Venus as a dazzling silvery star well above it in the west trying to steal attention away from Mars and Jupiter. Mars will slowly fade into the summer and Venus will drop from the sky in May as it heads for its historic transit across the Sun on June 5. This will leave Saturn to rule the evening alone during the summer months until it too fades into the twilight by late September. Mars will still linger feebly as autumn arrives but Jupiter will already be shining brightly in the east before midnight by then and once again it will rule the night as the holidays approach. Uranus and Neptune are never brilliant, but both are fun to locate and observe, and will be visible in the evening from August until next February. Here is the breakdown for each planet in the evening sky during 2012:
Mercury: This crater-riddled world is always challenging to find, but it is worth noting that there is a spacecraft currently orbiting it that is re-writing the textbooks. It is easiest to see in the evening from February 21 to March 15, being highest above the horizon on March 5. Mercury grows steadily through this period from 6 to 10 arcseconds across as it approaches Earth and its magnitude will hover around 0. It will go through phases like a tiny, coppery version of the Moon, from nearly full to a thin crescent.
Venus: This volcano-ravaged world has an excellent evening apparition as it will be at its highest possible on March 27 and brighten to magnitude -4.5 only a few weeks later. It reaches a historic inferior conjunction on June 5 when it transits the Sun for the second and last time during our lifetime while displaying a black disc that will be 57.8 arcseconds across. The transit begins later in the afternoon and remains visible through sunset. Venus will reappear in the morning sky a few weeks after the transit for an equally beautiful morning apparition. It will gradually fade and grow lower towards the end of the year. Venus always makes beautiful pairings with the crescent Moon in the evenings and mornings.
Mars: This dust-filled world is always exciting to observe and is the only planet where a solid surface can be clearly seen from Earth, provided there is no dust storm. Mars is almost as far away as it can be during an opposition when it reaches it on March 3; it will be barely 13.9 arcseconds across, but will still shine brightly at magnitude -1.2 in Leo near Virgo. The north polar ice cap should be prominent as it emerges from winter and it might be possible to watch it shrink in the months ahead. Dark features such as Syrtis Major should still be visible in spite of the small size. Much patience will assure some great views of Mars that will satisfy until it returns bigger and brighter in 2014. Mars will remain in good view until the start of summer and then very slowly shrink and fade into the evening twilight when the autumn chill returns.
Jupiter: This radiation-laced world is always very large and is a main attraction at star parties; however it is mainly a cold-weather planet for the next few years. Jupiter begins the year well up in the south during the early evening and will eventually become lost in the evening twilight by March as it fades to magnitude -2.0 and shrinks to 33 arcseconds across. Jupiter rises before midnight by October and is at opposition on December 2 in Taurus, when it will be 48.4 arcseconds across and blaze at magnitude -2.8. The long hours of darkness during the cold winter months will make it possible to observe a full rotation of Jupiter as it rotates once every 9 hours and 50 minutes. The swift rotation can be noticed in only ten minutes. The large size will allow for detailed viewing of the cloud belts, polar hoods, and Great Red Spot. It should be possible to see the tiny discs of the larger moons, Callisto and Ganymede, and to compare their size to smaller Europa and Io. It might even be possible to detect slight color differences among them.
Saturn: This ring-graced world is always the main attraction at any star party and this year is even better with it visible in the evening all summer with the rings at their widest opening in years. Saturn is at opposition on April 15 in Virgo when it will be 19.0 arcseconds across and shine at magnitude +0.2. There is much to see and the nicer weather will allow an excellent chance to study Saturn’s belts and spots, and to look for the Cassini Division in the rings. The largest moon, Titan, is usually visible and it might be possible to see a little peach coloring to it. Saturn will slowly fade to magnitude +0.9 and shrink to less than 17 arcseconds across by late September when it becomes lost in the evening twilight.
Uranus: This mist-shrouded world will be at opposition on September 29 in Pisces. Uranus will be 3.7 arcseconds across and shine at magnitude +5.7 to the lower left of the Great Square of Pegasus and east of the Circlet of Pisces.
Neptune: This storm-tossed world is at opposition on August 24 in Aquarius below the Water Jar. Neptune will be 2.4 arcseconds across and shine at magnitude +7.8. A finder chart for Uranus and Neptune will appear in the August issue of Telescopic Topics. Both planets will rise before midnight by August and gradually fade into the evening twilight by February 2013.
Pluto: This ice-covered world continues to slowly emerge from the heart of the Milky Way above the spout of the Sagittarius Teapot, but will still be a challenge to find. Pluto is at opposition on June 29 among thousands of stars and will shine like a faint spark at magnitude +14.0 and is only 0.1 arcseconds across. Locating Pluto will gradually become easier in the years ahead as it leaves the heart of the Milky Way by 2015 and crosses the ecliptic in 2018, but will grow slowly fainter and lower in declination for the rest of our lives as it moves steadily away from Earth.