Mercury reaches greatest eastern elongation on June 12th, when it's positioned 24.3 degrees east of the Sun. Unfortunately, for northern hemisphere observers this is not a great evening apparition. Despite the planet being visible for the first three weeks of June, it hardly climbs above the northwestern horizon. For those located in the tropics and southern hemisphere the situation is slightly better; Mercury appears a few degrees higher in the sky and therefore somewhat easier to find.
To spot the smallest of the eight planets this month you will require an unobstructed view of the west-northwestern horizon, some clear skies and preferably good seeing conditions. From London, England (51.5N), Mercury will be positioned at best only about 8 degrees above the northwestern horizon, 45 minutes after sunset during the first half of the month. As it's the height of summer in the northern hemisphere, the planet is even more difficult to locate as it struggles to standout against the long bright evening twilight. By June 20th, Mercury's altitude will have diminished to only 4 degrees. Those located in the southern hemisphere fare slightly better; Mercury appears a couple of degrees higher and twilight is less of a problem.
The planets brightness fades from magnitude –0.4 on June 1st to magnitude 1.4 on June 22nd. There is a good opportunity to catch Mercury on June 20th or June 21st when it's once again quite close in the sky to the much brighter Venus (mag. –3.8).
Venus continues to head east from the Sun during June and hence is becoming easier to locate in the evening twilight towards the west / northwestern horizon. Despite the improving apparition, northern hemisphere observers have to overcome the long evenings and bright twilight in order to spot the planet. For observers located further south, Venus should be easier to locate. As previously mentioned, on June 20th / June 21st Mercury and Venus appear close together in the sky.
During June, Venus shines at magnitude –3.8 with an apparent diameter of about 11 arc seconds.
Mars is gradually becoming visible as a morning object for those located in the tropics and southern hemisphere. Towards the end of June it appears low down above the east-north-eastern horizon about an hour or so before sunrise. For observers at northern temperate latitudes, Mars remains inconveniently placed for observation during June.
The "Red planet" is currently located in Taurus and shines at magnitude 1.5, towards the lower end of its magnitude range.
Jupiter reaches solar conjunction on June 19th and is therefore positioned too close to the Sun to be observed this month.
Saturn continues to move retrograde in eastern Virgo this month, close to the constellation border with Libra. It's visible towards the east-southeast as soon as it gets dark and remains observable until the early hours of the morning although we're now approaching the tail end of this apparition. Due to its southerly declination, the planet is currently better placed for observation for those located at southern and tropical latitudes rather than the northern hemisphere.
It's now over a month since Saturn passed opposition (April 28th) and subsequently the distance between the planet and the Earth continues to gradually increase. On June 1st, Saturn is located 9.0 AU from Earth, which increases to 9.3 AU by June 30th. As a result, the ringed planet's apparent size slightly decreases from 18.5 to 17.8 arc seconds and its magnitude fades from 0.3 to 0.5 this month.
To the naked eye Saturn appears yellowish. Through a telescope the planets rings are a beautiful sight, visible with just a small instrument and currently wide open. A medium sized telescope of the order of 150mm (6-inch) or 200mm (8-inch) aperture will show a wealth of detail including subtle planet surface details, divisions in the rings as well as up to half a dozen of Saturn's satellites.
The waxing gibbous Moon passes 4 degrees south of Saturn on June 19th.
Uranus is now a morning object in Pisces. As the month progresses the planets visibility steadily improves. For northern hemisphere based observers at the start of June, Uranus is just about visible above the eastern horizon before twilight interferes. By months end Uranus is much higher in the sky, rising about 4 hours before the Sun.
Observers located further south have it even better with Uranus well placed in the morning sky throughout June. At the start of June, the planet rises 4 hours before the Sun and by the end of the month it's visible from about midnight.
The magnitude of the seventh planet from the Sun is 5.9 and it has an apparent diameter of about 3.5 arc seconds. On June 30th, the last quarter Moon passes 4 degrees north of Uranus.
Neptune (mag. 7.9) is a morning object in Aquarius that's positioned only 0.5 degrees north of star sigma (σ) Aqr (mag. 4.8). As the distant planet moves towards opposition in August its period of visibility continues to improve throughout June. Like Uranus, Neptune is better placed for observation from the tropics and southern hemisphere where it rises in late evening by months end.
Solar System Data Table June 2013
|Date||Right Ascension||Declination||Apparent Magnitude||Apparent Size||Illum. (%)||Distance from Earth (AU)||Constellation|
|Sun||5th Jun 2013||04h 51m 57.3s||22d 30m 59.2s||-26.7||31.5'||100||1.015||Taurus|
|Sun||15th Jun 2013||05h 33m 21.6s||23d 17m 46.0s||-26.7||31.5'||100||1.016||Taurus|
|Sun||25th Jun 2013||06h 14m 56.3s||23d 23m 35.7s||-26.7||31.5'||100||1.016||Gemini|
|Mercury||5th Jun 2013||06h 30m 24.9s||25d 17m 13.7s||-0.1||07.0"||54||0.966||Gemini|
|Mercury||15th Jun 2013||07h 18m 26.7s||22d 58m 47.9s||0.6||08.6"||34||0.782||Gemini|
|Mercury||25th Jun 2013||07h 37m 30.7s||19d 57m 51.5s||1.9||10.5"||16||0.641||Gemini|
|Venus||5th Jun 2013||06h 09m 25.7s||24d 24m 56.2s||-3.8||10.3"||95||1.614||Gemini|
|Venus||15th Jun 2013||07h 02m 56.4s||23d 57m 40.6s||-3.8||10.6"||93||1.576||Gemini|
|Venus||25th Jun 2013||07h 55m 25.6s||22d 20m 52.5s||-3.8||10.9"||92||1.532||Gemini|
|Mars||5th Jun 2013||04h 03m 59.0s||20d 52m 51.6s||1.4||03.8"||100||2.467||Taurus|
|Mars||15th Jun 2013||04h 33m 50.3s||22d 11m 05.8s||1.5||03.8"||99||2.465||Taurus|
|Mars||25th Jun 2013||05h 03m 47.1s||23d 08m 13.8s||1.5||03.8"||99||2.459||Taurus|
|Jupiter||5th Jun 2013||05h 38m 11.6s||23d 05m 26.4s||-1.9||32.3"||100||6.109||Taurus|
|Jupiter||15th Jun 2013||05h 48m 08.6s||23d 10m 26.8s||-1.9||32.1"||100||6.133||Taurus|
|Jupiter||25th Jun 2013||05h 58m 07.4s||23d 13m 02.5s||-1.9||32.1"||100||6.136||Taurus|
|Saturn||5th Jun 2013||14h 16m 18.9s||-10d 53m 20.3s||0.3||18.4"||100||9.021||Virgo|
|Saturn||15th Jun 2013||14h 14m 35.7s||-10d 46m 45.5s||0.4||18.2"||100||9.136||Virgo|
|Saturn||25th Jun 2013||14h 13m 25.6s||-10d 43m 16.6s||0.4||17.9"||100||9.270||Virgo|
|Uranus||5th Jun 2013||00h 43m 46.9s||03d 57m 45.4s||5.9||03.4"||100||20.493||Pisces|
|Uranus||15th Jun 2013||00h 44m 51.9s||04d 04m 19.7s||5.9||03.5"||100||20.339||Pisces|
|Uranus||25th Jun 2013||00h 45m 40.8s||04d 09m 10.3s||5.9||03.5"||100||20.175||Pisces|
|Neptune||5th Jun 2013||22h 29m 00.2s||-10d 13m 06.1s||7.9||02.3"||100||29.808||Aquarius|
|Neptune||15th Jun 2013||22h 28m 57.1s||-10d 13m 44.9s||7.9||02.3"||100||29.644||Aquarius|
|Neptune||25th Jun 2013||22h 28m 42.0s||-10d 15m 32.9s||7.9||02.3"||100||29.489||Aquarius|