Royal Astronomical Society of New Zealand
The Planets in 2011
Mercury is an evening object from February 25 to April 19, June 12 to August 17, and September 28 to December 4. As is usual for the southern hemisphere, the best evening apparition is late winter, this year towards the end of July, when Mercury will set well over 2 hours after the Sun. The planet is brighter early July.
For northern hemisphere observers the best evening apparition is in early May and the best morning apparition is early in November.
Mercury and Mars are in conjunction on April 20 and again on May 21. Mercury and Venus are in conjunction on May 9 and on May 19, Mercury and Jupiter on May 12. All these occur when the planets are in the morning sky. From late October to mid November, Mercury and Venus will be moving on parallel courses, at their closest 2° apart. They will then be visible in the evening sky.
Venus will be a morning object up to August 16 when it is at superior conjunction with the Sun. It then becomes an evening object for the rest of the year.
During February, Venus will rise about 3 and a half hours before the Sun. During May there will be a series of planetary conjunctions involving Mercury, Venus, Mars and Jupiter. Later in the year towards the end of September, Venus and Saturn are in conjunction; from late October to mid November Venus and Mercury are close.
Mars starts the year as a nominal evening object, but it will set shortly after the Sun and not be observable. On February 4 it is at conjunction with the Sun after which Mars becomes a morning object for the rest of the year.
It will be the beginning of April before Mars rises as much as an hour before the Sun, and this increase will be due to the Sun rising later, not Mars rising earlier. It will not be until mid August that Mars will rise before 5am, so will remain a low object visible only shortly before dawn.
Mars will also remain fainter than magnitude 1 until late in the year when it will start to brighten a little. So 2011 is no going to be a good year for observing the planet. However, it will take part in the series of conjunctions of 4 planets during May.
Jupiter is in Pisces during the first part of 2011, up to early June, apart from a few days at the end of February and beginning of March when it crosses a corner of Cetus. From early June on it will be in Aries, until the end of the year when retrograde motion will see the planet briefly return to Pisces.
The planet is at conjunction on April 6 and opposition on October 29. Consequently it will be an early evening object during the first part of the year, disappearing into the sunset glow during March. It will again be visible in the evening sky in the last three months of 2011. From May to September it will be mostly visible in the morning sky.
At the beginning of January, Jupiter will again be in conjunction with Uranus, the planets being closest on the 4th. This is the last of the set of three conjunctions, the others having been in 2010. After this conjunction Jupiter will move steadily away from Uranus. In May Jupiter will be one of four planets in the series of conjunctions occurring during the month.
Saturn is in Virgo for the whole of 2011. It starts the year as a morning object rising between 1 and 2 am NZDT in most of New Zealand. It will become visible in the late evening sky by the end of February. Saturn reaches opposition on April 3. By then it will rise at about the time the Sun sets and be in the sky all night.
When the planet is stationary for a second time at mid June, it will about 16 arc-minutes (about half the diameter of the full moon) from the third magnitude star γ Virginis.
Saturn is at conjunction with the Sun on October 13, after which it becomes a morning object rising before the Sun. The only conjunction of Saturn with a planet during 2011 will be with Venus on September 29. Since this is only two weeks before conjunction it will be difficult to observe in the evening twilight. A little over a month after conjunction, in mid November Saturn will be just over 4° from Spica, at 1.4 the brightest star in Virgo. The two will be in the morning sky with Saturn below Spica.
During 2011 the northern face rings of Saturn's rings will become noticably more exposed to view particularly by the end of the year.
Uranus is in Pisces throughout 2011. It starts the year close to Jupiter, the two being in conjunction on January 4 when they will be half a degree apart. Uranus is an evening object during the first part of the year, until it reaches conjunction with the Sun on March 17. After conjunction it becomes a morning object rising only just before the Sun at first, but getting steadily earlier during the following months. A conjunction with Venus occurs on April 23.
Uranus is stationary on July 10 and at opposition on September 26. By August it will be be observable in the late evening sky, and all evening by October.
Neptune starts 2011 in Capricornus but moves into Aquarius on January 23. In 2011, unlike 2010, it then stays in Aquarius for the rest of the year.
Neptune starts the year as an evening object setting shortly before midnight. By the end of January it will set only an hour after the Sun and so become lost to view. The planet is at conjunction with the Sun on February 17 after which it becomes a morning object, rising before the Sun.
The planet is stationary on June 3, and reaches opposition on August 22 by which time it will be visible in the evening sky. The planet is stationary again on November 9.
|Morning Sky||Evening Sky|
|Jan 9, 23°W
May 7, 27°W
Sep 20 18°W
Dec 23, 22°W
|Mar 22, 19°E
Jul 20, 27°E
Nov 14, 23°E
|Venus||Jan 8, 47°W||Aug 16|
|Morning Sky||Evening Sky|
|Jupiter||Apr 6||Aug 30||Oct 29||Dec 26|
|Saturn||Jan 27||Apr 3||Jun 14||Oct 13|
|Uranus||Mar 21||Jul 10||Sep 26||Dec 10|
|Neptune||Feb 17||Jun 3||Aug 22||Nov 9|
|Pluto||2010 Dec 27||Apr 9||Jun 28||Sep 16||Dec 29|
The separations are in minutes of arc. The diameter of the full moon is about 30' (half a degree). Dates are as in New Zealand, for morning events the UT date is one less.
In 2011 most of the conjunctions are morning events occurring in late April and in May, when Mercury, Venus, Mars and Jupiter are all quite close to one another. Of the naked eye planets only Saturn is missing. The charts show the paths of the planets with their positions marked every second day.
Jupiter and Mars, May 1/2 Venus, Jupiter and Mercury, May 1 Venus, Mercury and Mars, May 18 to 24
|Date closest||Planets||Minimum distance||Notes|
|Jan 4||Jupiter (-2.3) and Uranus (5.9)||31'||Evening sky, Uranus to lower right of Jupiter.|
|Feb 10||Venus (-4.2) and Pluto (14.3)||141'||Morning sky, Pluto to lower left of Venus|
|Mar 27||Venus (-4.0) and Neptune (8.0)||27'||Morning sky, Neptune below Venus.|
|Apr 20||Mars (1.2) and Mercury (2.5)||38'||Morning sky, Mercury to left of Mars, very low.|
|Apr 24||Venus (-3.9) and Uranus (5.9)||69'||Morning sky, Uranus left of and a little higher than Venus.|
|May 1/2||Jupiter (-2.1) and Mars (1.3)||25'/29'||Morning sky, Mars to left of Jupiter, May 1, lower left May 2.|
|May 9/10||Venus (-3.9) and Mercury (0.5)||86'/87'||Morning sky, Mercury to right and a little higher than Venus.|
|May 12||Jupiter (-2.1) and Mercury (0.3)
Venus (-3.9) and Jupiter (-2.1)
|Morning sky, Mercury to right and a little higher than Jupiter.
Jupiter to left of Venus.
|May 18/19||Venus (-3.9) and Mercury (0.0)||82'||Morning sky, Mercury to right of Venus.|
|May 21/22||Mercury (-0.2) and Mars (1.3)||130'||Morning sky, Mars to left of, and a little lower than Mercury.|
|May 24||Venus (-3.9) and Mars (1.3)||60'||Morning sky, Mars to left of Venus.|
|Sep 29||Venus (-3.9) and Saturn (0.8)||89'||Evening, Saturn to right of Venus, very low in sunset sky.|
|Nov 1 to 12||Venus (-3.9) and Mercury (-0.3)||120'||Evening sky, Mercury to left of and a little higher than Venus.|