Mercury remains a morning object for observers in the tropics and Southern Hemisphere for about the first 10 days of July. The nearest planet to the Sun may be spotted about 45 minutes before sunrise in the twilight sky low down above the east-northeastern horizon; brightening from magnitude -0.1 to -0.9 during this time period. Mercury is then unobservable for the remainder of the month as it moves closer ever in the sky to the Sun. The planet reaches superior conjunction on July 23rd.
From northern temperate latitudes Mercury is unobservable during July.
The diagram below shows the June / July morning apparition of Mercury from a latitude of 35S (approx. equal to Sydney, Cape Town and Santiago). Positions of the planet are displayed 45 minutes before sunrise.
Venus continues its run as brilliant evening star this month although from mid-northern temperate locations the observation period shortens noticeably and from about the middle of the month the brightest planet will be lost to the sunset. From more southerly latitudes Venus remains visible throughout July.
On July 10th, Venus attains its greatest brilliance when it peaks at magnitude -4.7. Before this on July 1st it passes only 0.4 degrees south of Jupiter (mag. -1.8) with Venus 15 times the brighter of the pair. Another conjunction occurs on July 19th when the waxing crescent Moon passes 0.4 degrees south of Venus with an occultation visible from northeastern Australia and the French Polynesia (1:07 UT).
On July 23rd, Venus reaches a stationary point in Leo, afterwards retrograde motion commencing. It then draws back towards the Sun with the planet once again passing south of Jupiter on July 31st although this time the separation is more than 6 degrees. Of course the events described during the second half of July are only visible from more southerly climes.
During the month the Venus phase decreases from 33% to a very slim 8% crescent.
Earth is at aphelion - furthest from the Sun - on July 6th at a distance of 1.017 AU (152 million kilometers or 94.5 million miles).
Mars reached solar conjunction on June 14th. The Red planet is currently located on the far side of the Sun and remains unsuitable placed for observation throughout July.
Jupiter, mag. -1.8, continues to be visible as an early evening object during July although observers at northern temperate latitudes are likely to lose the planet to the bright long evening twilight during the third week of the month. The largest planet of the Solar System can be seen low down towards the western horizon as soon as it dark enough.
Now moving direct in Leo, Jupiter's long evening period of visibility is almost over as it heads towards next month's solar conjunction. As previously mentioned, much more brilliant Venus will pass less than half a degree south of Jupiter on July 1st. For those located at tropical and southern latitudes another Venus - Jupiter conjunction occurs on July 31st. On this occasion Venus passes 6 degrees south of Jupiter.
The thin waxing crescent Moon passes 4 degrees south of Jupiter on July 18th.
Only two months passed opposition, Saturn remains an evening object during July. The beautiful planet famous for it's wonderful ring system continues to move slowly retrograde amongst the faint stars of Libra. It appears to the naked eye as off-white or creamy "star" located 10 degrees northwest of orange/red first magnitude red giant Antares (α Sco mag. +1.0).
Saturn is visible as soon as it's dark enough towards the south-southeast from northern temperate latitudes or towards the northeast from south latitudes. It sets just after midnight at months end from northern latitudes although two hours later for those further south.
The planet fades slightly from magnitude +0.2 to +0.4 with its apparent diameter shrinking from 18.1 to 17.3 arc seconds as the month progress.
On July 26th, the waxing crescent Moon passes 2 degrees north of Saturn.
Uranus is now well placed for observation amongst the stars of Pisces. At magnitude +5.8 Uranus is actually visible to the naked eye, albeit faintly. To achieve this goal a dark moonless site is required along with good seeing conditions and a good star chart to pinpoint the exact location.
At the start of July from northern temperate locations, Uranus rises 4 hours before sunrise and by months end is visible from about midnight. The visibility period from locations further south is even better with Uranus visible in the evening sky by months end.
On July 9th the last quarter Moon passes 0.8 degrees south of Uranus with an occultation visible from Western Australia and the Southern Indian Ocean at 2:47 UT. Two weeks later on July 26th, Uranus reaches its first stationary point signaling the beginning of this year's opposition period. The planet then commences retrograde motion.
Neptune (mag. +7.8) is moving retrograde in Aquarius as it heads towards opposition on September 1st. The eighth and most distant planet from the Sun is positioned about 30 degrees southwest of the Great Square of Pegasus and a few degrees southwest of star lambda (λ) Aqr (mag. +3.7). It now rises before midnight from northern temperate latitudes and up to a couple of hours earlier from locations further south.
Although observers may be able to spot Uranus with the naked eye they have no chance do the same with Neptune, it's far too faint. However, the planet is relatively easy to spot binoculars.
On July 6th, the waning gibbous Moon passes 3 degrees north of Neptune.
Solar System Data Table July 2015
|Date||Right Ascension||Declination||Apparent Magnitude||Apparent Size||Illum. (%)||Distance from Earth (AU)||Constellation|
|Sun||5th July 2015||06h 54m 14.1s||22d 51m 08.0s||-26.7||31.5'||100||1.017||Gemini|
|Sun||15th July 2015||07h 35m 07.1s||21d 38m 18.9s||-26.7||31.5'||100||1.017||Gemini|
|Sun||25th July 2015||08h 15m 11.8s||19d 48m 41.6s||-26.7||31.5'||100||1.016||Cancer|
|Mercury||5th July 2015||05h 31m 37.1s||21d 48m 23.0s||-0.5||06.4"||63||1.052||Taurus|
|Mercury||15th July 2015||06h 51m 26.6s||23d 26m 21.1s||-1.4||05.4"||91||1.250||Gemini|
|Mercury||25th July 2015||08h 22m 32.9s||21d 07m 53.9s||-2.1||05.0"||100||1.340||Cancer|
|Venus||5th July 2015||09h 44m 20.1s||13d 37m 45.1s||-4.7||34.3"||31||0.486||Leo|
|Venus||15th July 2015||10h 00m 48.9s||10d 27m 27.1s||-4.7||40.2"||22||0.415||Leo|
|Venus||25th July 2015||10h 05m 17.9s||07d 52m 07.2s||-4.6||47.2"||13||0.354||Leo|
|Mars||5th July 2015||06h 29m 45.3s||24d 02m 29.0s||+1.6||03.6"||100||2.586||Gemini|
|Mars||15th July 2015||06h 58m 45.4s||23d 36m 20.6s||+1.6||03.6"||100||2.587||Gemini|
|Mars||25th July 2015||07h 27m 14.6s||22d 51m 09.1s||+1.7||03.6"||100||2.582||Gemini|
|Jupiter||5th July 2015||09h 39m 01.0s||14d 57m 13.9s||-1.8||32.2"||100||6.118||Leo|
|Jupiter||15th July 2015||09h 46m 37.7s||14d 18m 38.0s||-1.8||31.7"||100||6.212||Leo|
|Jupiter||25th July 2015||09h 54m 32.0s||13d 37m 34.9s||-1.7||31.4"||100||6.287||Leo|
|Saturn||5th July 2015||15h 47m 44.4s||-17d 49m 44.2s||+0.2||18.0"||100||9.227||Libra|
|Saturn||15th July 2015||15h 46m 14.0s||-17d 47m 10.2s||+0.3||17.8"||100||9.351||Libra|
|Saturn||25th July 2015||15h 45m 20.3s||-17d 46m 41.5s||+0.3||17.5"||100||9.493||Libra|
|Uranus||5th July 2015||01h 15m 12.9s||07d 15m 42.9s||+5.8||03.5"||100||20.101||Pisces|
|Uranus||15th July 2015||01h 15m 42.8s||07d 18m 26.3s||+5.8||03.5"||100||19.933||Pisces|
|Uranus||25th July 2015||01h 15m 54.7s||07d 19m 20.0s||+5.8||03.6"||100||19.766||Pisces|
|Neptune||5th July 2015||22h 45m 19.8s||-08d 45m 21.8s||+7.9||02.3"||100||29.398||Aquarius|
|Neptune||15th July 2015||22h 44m 48.4s||-08d 48m 51.3s||+7.8||02.3"||100||29.265||Aquarius|
|Neptune||25th July 2015||22h 44m 07.5s||-08d 53m 16.8s||+7.8||02.3"||100||29.152||Aquarius|