The Solar system in July
All dates and times are NZST (UT +12 hours) unless otherwise specified. Rise and set times are for Wellington. They will vary by a few minutes elsewhere in NZ.
The Sun rises at 7.45 am and sets at 5.04 pm on July 1. On July 30 the times are 7.27 am and 5.27 pm respectively.
Phases of the Moon (times as shown by guide)
First quarter: July 5 at 11.59 pm ( 11:59 UT) Full moon: July 12 at 11.25 pm ( 11:25 UT) Last quarter July 19 at 2.08 pm ( 02:08 UT) New moon: July 27 at 10.42 am (Jul 26, 22:42 UT)
The Planets in July
Mars and Saturn are visible in the evening sky while Mercury and Venus are morning sky objects. Jupiter is a very low evening object early in July but is at conjunction on the 25th.
The two asteroids, Ceres and Vesta have been a close pair this year. They are at their closest in July, only 10 arc-minutes apart early in the month.
MERCURY is a morning object during July. It rises some 80 minutes before the Sun on July 1 with a magnitude 2.4. 45 minutes before sunrise it will be 5° up at an azimuth of 60°. So it will not be not an easy object in the dawn sky.
Things improve a little over the next few days. On the 13th it reaches its greatest elongation, 21° west of the Sun. Its magnitude then will be 0.4, so 2 magnitudes brighter and 7° up at an azimuth 55° 45 minutes before sunrise.
By the 20th Mercury will be at magnitude -0.4, but only 4° above the horizon 45 minutes before sunrise. The planet gets closer to the Sun during the rest of the month.
VENUS is also in the morning sky and rises 40 to 50 minutes before Mercury all month. Venus starts the month 4° from Aldebaran, the distance increasing to 10° by the 31st.
On the 25th a very thin crescent moon only 4% lit will be 4° to the upper right of Venus, about midway between the planet and the 2nd magnitude star gamma Geminorum.
MARS is losing brightness as the faster-moving Earth moves ahead of, and further from, the red planet. During July, Mars dims slightly from magnitude 0.0 to 0.4. It transits at 6.51 pm on the 1st and 5.46 pm on the 31st, so is highest in the early evening. Mars remains in Virgo, a few degrees from Spica. The two are closest on the 14th with Mars 1.3° to the lower right of Spica early in the evening. By late evening the sky's rotation will bring Mars almost level with Spica still to its right.
The 58% lit moon joins Mars and Spica on the on the 6th. Early evening the moon will be 2.4° from Mars, during the evening the moon will move a little closer to Spica, so that by 8 pm the moon and star will be 2.4° apart. Earlier in the day, the moon will occult Mars, the event being visible from northern parts of South America.
The two asteroids Ceres and Vesta continue to be near Mars all month. During the second half of July they will be about 7° from the planet.
JUPITER sets some 80 minutes after the Sun at the beginning of July, so will be a very low object only 7° up and round towards the northwest half an hour after sunset. The planet closes in on the Sun through the month so becoming lost to view within a few days. It is at conjunction with the Sun on the 25th.
At conjunction Jupiter will be 940 million km from the Earth, 788 million km beyond the Sun. At its closest it will pass 8 arc minutes north of the Sun as "seen" from the Earth.
SATURN transits at 8.44 pm, two hours after Mars, on the 1st and 6.45 on the 31st, only 1 hour after Mars. That is the two planets get closer during the month, with a separation of about 14° by its end. Saturn is in Libra and will reach a stationary point on the 21st. Hence it will show little change in its position during July, just under 2.5° from alpha Librae.
The 77% lit moon will be 2.5° from Saturn on July 8, with Saturn between the moon and Alpha Lib. As is the case for Mars, the moon will occult Saturn earlier in the day. In this case the occultation is visible from southern parts of South America. The paths of the occultations will not overlap, there will be a strip of the continent between the two which see neither event.
URANUS rises an hour after midnight on July 1st and an hour before on the 31st. The planet is in Pisces at magnitude 5.8.
NEPTUNE rises at 9.42 p on the 1st and 6.41 pm on the 31st . It is in Aquarius with a magnitude 7.8 by the month's end.
PLUTO is at opposition on July 8. The dwarf planet is in Sagittarius at magnitude 14.3, position RA 18hr 51.1 min, Dec -2° 19'. This places it 1.7° from the mag 3.5 star xi2 Sgr and 40" south of the 7.6 mag star V4088 Sgr.
(1) Ceres and (4) Vesta are at their closest on July 5 and 6, when they will be 10 arc-minutes apart, about one-third the diameter of the full moon. Vesta'a magnitude ranges from 7.1 to 7.5 during July, Ceres's 8.4 to 8.8.
The two asteroids are also close to Mars some 7 or 8 degrees from the planet. All three are in Virgo. On the 14th when Mars is closest to Spica, the two asteroids will be 7° from the planet on the opposite to Spica.
The follwing table lists various solar system object events during July. A list of astronomical terms used in may be found after the table.
|July 1||Mercury stationary
Regulus 4.6 degrees north of the Moon
Venus 4.1 degrees north of Aldebaran
|July 4||Earth at aphelion
Pluto at opposition
|July 5||Moon first quarter|
|July 6||Mars 0.2 degrees south of the Moon Occn
Spica 2.0 degrees south of the Moon
|July 8||Saturn 0.4 degrees north of the Moon Occn|
|July 10||Moon southern most declination (-19.0 degrees)|
|July 11||Pluto 2.3 degrees south of the Moon|
|July 12||Moon full
Mercury greatest elong W(21)
|July 13||Moon at perigee|
|July 14||Mars 1.3 degrees north of Spica|
|July 15||Neptune 4.4 degrees south of the Moon|
|July 18||Uranus 1.4 degrees south of the Moon|
|July 19||Moon last quarter|
|July 21||Saturn stationary|
|July 22||Uranus stationary
Aldebaran 1.8 degrees south of the Moon
|July 23||Moon northern most declination (18.9 degrees)|
|July 24||Venus 4.4 degrees north of the Moon
Jupiter at conjunction
|July 25||Mercury 5.0 degrees north of the Moon|
|July 26||Jupiter 5.3 degrees north of the Moon
|July 28||Moon at apogee|
|July 29||Regulus 4.4 degrees north of the Moon|
- aphelion: Furtherest point in the orbit of a body orbiting the Sun
- apogee: Furtherest point in the orbit of a body orbiting the Earth
- conjunction: Two astronomical objects are 'lined up' (have the same right ascension) when viewed from Earth
- declination: 'Latitude' for celestial objects. The distance in degress above (north) or below (south) the celestial equator.
- perigee: Nearest point in the orbit of a body orbiting the Earth