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What's Up?

posted May 10, 2012, 8:27 PM by Mike White   [ updated Jul 9, 2012, 2:01 AM ]
Every month, the Royal Astronomical Society of NZ (RASNZ) issues information about what solar system objects are viewable for the month.  We will update that information here to share with you as it becomes available.

The usual notes on the visibility of the Planets for July 2012 are on the RASNZ web site:  Notes for August 2012 will be on line in a few days.


Mars and Saturn will be visible in the first part of the evening, but get rather low in the later part of the evening.  During the month the separation of the two planets will decrease as Mars moves towards Saturn and Spica.

Mercury will be an easy object to the northwest an hour after sunset for the first two weeks of July.  It will then get lower and fainter to become lost in the setting Sun´s glare within a few days.

In the morning Venus and Jupiter will be level and quite close in the dawn sky at the beginning of the month.  During the month Jupiter gets higher.


MERCURY will be quite easy to see in the early evening during the first half of July.  Best viewing is likely to be 45 minutes to an hour after sunset.  As the month progresses Mercury will get fainter, its magnitude changing from 0.6 on the 1st to 1.9 on the 15th.   An hour after sunset the planet will have an altitude about 10° and be to the northwest. Procyon will be some 20° to the left of Mercury and a little brighter than the planet.  Sirius will be another 25° away and noticeably higher.

After mid July Mercury will continue to fade and get lower in the evening sky as it heads back towards the Sun.  It is at inferior conjunction on July 29 but no transit.  The planet will pass 5° to the south of the Sun.

MARS and SATURN are both in Virgo throughout July.  They will be readily visible in the first part of the evening, getting lower later.  Mars sets between a little before midnight at first, half an hour earlier by the end of the month.  Saturn sets a couple of hours after Mars on the 1st but only 40 minutes later on the 31st.

During July the distance between the two planets will steadily decrease, falling from 25° to 8° as Mars moves to the east through Virgo.

Saturn remains paired with Spica throughout July, with the two less than 5° apart.  Saturn will be lower and slightly brighter than the star.

The distance between Mars and the Earth increases from 212 to 243 million km in July, its brightness will correspondingly drop from magnitude 0.9 to 1.1.  So by the end of July Mars will be similar in brightness to Spica, but the two will of course be rather different in colour.

The moon passes the planets on July 24 and 25.  On the 24th it will be 27% lit and 8° to the lower left of Mars.   The following night the moon will form more of a group with the planets and Spica.  The 38% lit moon will be 7° above Mars and the same distance to the left of Saturn.  Spica will be a little closer to the moon, 5.5° to its upper right.


VENUS and JUPITER are in Taurus: early in July both are to the left of Aldebaran.  At first they will rise almost simultaneously, some 2 hours and 40 minutes before the Sun. The two planets will be about 5° apart with Venus to the right of Jupiter for the first week or so as they both move slowly to the east through the stars.  After a few days Venus will be begin to move more rapidly than Jupiter so will move below and to the right of the gas giant as the month progresses.  By the end of July the two will be 14° apart.

Jupiter starts July about midway between the Pleiades, to its left, and Aldebaran to its right.  Venus starts the month in the Hyades.   Jupiter, moving more slowly than Venus, will end July with Aldebaran a little above it and to its right.  By then Jupiter will be rising nearly 4 hours before the Sun and so be higher in the dawn sky.

URANUS is stationary on July 13 so its position barely changes during the month.  It will be at magnitude 5.8 located in a corner of Cetus close to Pisces.  By the end of July it will rise a little before 11pm so remaining essentially a morning object.

NEPTUNE is in Aquarius during July moving very slowly to the west.  Its magnitude will be between 7.9 and 7.8.  By the end of July it will rise about 7.30 pm, so will be well positioned a little to the north of east by late evening.

Both Uranus and Neptune will also be visible as morning objects.


(1) Ceres and (4) Vesta are both morning sky objects in Taurus in the vicinity of Jupiter, Venus and Aldebaran.

At the beginning of July, Ceres at magnitude 9.2 will be less than 4° above Jupiter and 5° to the upper left of Venus.  Vesta will be a little over 6° above and a little left of Ceres, and little brighter at magnitude 8.5.

Ceres will be 3.3° to the upper right of Jupiter at their closest on July 12, and on the edge of the Hyades.  A week later it will lie between Jupiter and Aldebaran, 1.5° from the star and 3.5° from the planet.  By the end of July, Ceres will be at magnitude 9.1 and 4.6° to the right of Jupiter.

Vesta is moving to the east slightly faster than Ceres.  It ends July in the Hyades some 5° above Jupiter and 2° to the upper left of Aldebaran. Ceres will be barely 6° to Vesta´s the lower right.

By the end of July the two asteroids along with Jupiter and Aldebaran will be between 10 and 15° to the upper left of Venus.

No other asteroids are within reach of binoculars during July.

More details and charts for these minor planets can be found on the RASNZ web site.  Follow the link to asteroids 2012.