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Mercury reaches superior conjunction on the far side of the Sun on June 6th. The fast moving planet then moves rapidly out from the Sun to become an early evening object, visible low down above the western horizon, during the second half of the month. It subsequently improves in altitude each evening, although fading in brightness at the same time. However from northern temperate locations, Mercury has to battle against the bright evening twilight and therefore best glimpsed towards the end of month. On June 15th, the planet shines at magnitude -1.2 but by months end it will have dropped to magnitude -0.2. Mercury then sets up to 90 minutes after the Sun. Much brighter Venus, is located in the same region of sky, although considerably higher above the horizon.

On June 25th, Mercury passes 5 degrees south of Pollux (mag. +1.1). At magnitude +0.4, Mercury will be the brighter of the pair.


Venus continues to illuminate the western sky after sunset. The brilliant "evening star" is visible as soon as it's dark enough and dominates the view. Brighter than all other planets, Venus continues to increase in brightness, improving from magnitude -3.9 to -4.1 as the month progresses. During this time, its angular size increases slightly from 13 to 15 arc seconds. Venus begins June in Gemini, close to Pollux (mag. +1.1), before moving into Cancer on the June 11th. Later on June 19th and 20th, it passes near to M44, also know as the Praesepe or Beehive Cluster. Throughout the month the planet sets between 2.5 to 3 hours after the Sun.

On June 16th, the thin waxing crescent Moon passes a couple of degrees south of Venus, providing pleasant early evening viewing.

Venus and the crescent Moon, as seen from mid-latitude northern locations, just after sunset on June 16, 2018 (credit:- freestarcharts)


Mars, in Capricornus, brightens quite dramatically this month as it heads towards its much anticipated opposition in July. The red planet starts the month at magnitude -1.2, but by months end it will have more than doubled in brightness to magnitude -2.1. During the same time period, its apparent size improves from 15 to 21 arc seconds. With a small telescope, it's now possible to spot details, such as Syrtis Major, on its pink surface. Since Capricornus is a faint constellation with no stars above 3rd magnitude, Mars dominates this region of sky.

From northern temperate locations, the planet rises about midnight at the start of the month, improving by about 90 minutes at months end. Further south, Mars is superbly placed for observation. For example, from Sydney, Australia it rises just prior to 9:00pm at the onset of June, but by months end is visible from 7:15pm. During the night as it passes the meridian, Mars reaches a peak altitude of some 78 degrees above the northern horizon.

On June 3rd, the waning gibbous Moon passes 3 degrees north of Mars. On June 28th, Mars reaches its first stationary point, which signals the beginning of this year's opposition period. The planet then commences retrograde motion.

Mars and Saturn during June 2018 (credit:- freestarcharts)

Mars and Saturn during June 2018 - pdf format (credit:- freestarcharts)


Jupiter is now a month past opposition and remains a stunning object moving retrograde in Libra. As soon as it's dark enough, the gas giant is visible towards the east and remains so until the early hours of the morning. Jupiter starts the month at mag. -2.5 with an apparent diameter of 44 arc seconds. By months end it has faded slightly to mag. -2.3 and shrunk to 41 arc seconds.

When viewed through a telescope a wealth of Jovian cloud details are visible including bands, twists, knots and storms. Also easily visible, but not always at the same time, are the four bright Galilean moons: Io, Europa, Ganymede and Callisto.

A lovely pairing occurs on the night of June 23rd when the waxing gibbous Moon passes four degrees north of Jupiter.

Jupiter during June 2018 (credit:- freestarcharts)

Jupiter during June 2018 - pdf format (credit:- freestarcharts)


Saturn, mag. 0.0, reaches opposition in Sagittarius on June 27th. This month, the sixth planet from the Sun, is at its best for the year and practically visible all night long. With a declination of -22 degrees, Saturn is much better placed from southern and tropical locations. It appears higher in the sky and has a longer visibility period than from northern temperate latitudes.

At opposition, Saturn is 9.049 AU (1,354 million kilometres or 841 million miles) from Earth. Even a small telescope will show its most famous feature, the spectacular ring system. Also easily visible is Titan, the largest and brightest moon, which at 8th magnitude can be spotted with binoculars. Small scopes reveal other moons including Rhea, Tethys and Dione. In total, Saturn's disk spans 18.4 arc seconds in diameter.

On June 1st and 28th, the full Moon passes 2 degrees north of Saturn.

Saturn as imaged by the Cassini space probe (credit:- NASA/JPL-Caltech/SSI)


Uranus, mag. +5.9, is located in Aries. For northern temperate observers, the planet is lost to the bright twilight during the first half of the month, but by months end rises over three hours before the Sun. Observers located further south have it better with Uranus visible throughout June. At the end of the month, from such locations, it rises a few hours after midnight.

The waning crescent Moon passes 5 degrees south of Uranus on June 10th.

Uranus during June 2018 (credit:- freestarcharts)

Uranus during June 2018 - pdf format (credit:- freestarcharts)


Neptune, mag. +7.9, is in Aquarius. By months end the distant planet rises a couple of hours after midnight from northern temperate latitudes and before midnight for those located further south. Neptune is located about 30 degrees south and slightly west of the centre of the Great Square of Pegasus. It can be found about a quarter of the way along an imaginary line connecting phi Aquarii (φ Aqr - mag. +4.2) with lambda Aquarii (λ Aqr - mag. +3.7). Although the distance ice giant is the only planet that's not visible to the naked eye, it can easily be seen with binoculars and small telescopes.

On June 6th, the last quarter Moon passes 2 degrees south of Neptune. Later on June 19th, Neptune reaches its first stationary point, which signals the beginning of this year's opposition period. The planet then commences retrograde motion.

Neptune during June 2018 (credit:- freestarcharts)

Neptune during June 2018 - pdf format (credit:- freestarcharts)

Solar System Data Table - June 2018

 DateRight AscensionDeclinationMag.App. SizeIllum. (%)Dist. (AU)Constellation
SunJun 0104h 34m 24.1s21d 58m 47.3s-26.731.5'1001.014Taurus
SunJun 1505h 32m 12.3s23d 16m 58.7s-26.731.5'1001.016Taurus
SunJun 3006h 34m 32.2s23d 11m 58.3s-26.731.5'1001.017Gemini
MercuryJun 0104h 08m 09.0s20d 48m 44.8s-1.75.2"971.305Taurus
MercuryJun 1506h 18m 49.5s25d 09m 40.1s-1.25.3"911.266Gemini
MercuryJun 3008h 13m 56.9s21d 23m 09.8s-0.26.5"631.040Cancer
VenusJun 0107h 04m 10.3s24d 31m 26.2s-3.913.1"801.271Gemini
VenusJun 1508h 14m 51.6s21d 53m 56.9s-4.014.2"761.177Cancer
VenusJun 3009h 25m 23.7s17d 03m 33.7s-4.115.6"701.068Leo
MarsJun 0120h 32m 49.4s-21d 46m 51.2s-1.215.3"910.612Capricornus
MarsJun 1520h 46m 20.7s-21d 55m 28.9s-1.617.8"930.526Capricornus
MarsJun 3020h 50m 55.3s-22d 46m 58.7s-2.120.7"960.453Capricornus
JupiterJun 0114h 52m 57.7s-15d 16m 05.9s-2.544.1"1004.468Libra
JupiterJun 1514h 47m 51.7s-14d 56m 32.9s-2.443.0"1004.580Libra
JupiterJun 3014h 44m 36.4s-14d 45m 41.4s-2.341.5"994.746Libra
SaturnJun 0118h 32m 11.0s-22d 21m 01.9s0.218.2"1009.153Sagittarius
SaturnJun 1518h 28m 10.2s-22d 24m 37.8s0.118.3"1009.073Sagittarius
SaturnJun 3018h 23m 26.8s-22d 28m 40.1s0.018.4"1009.050Sagittarius
UranusJun 0101h 54m 35.9s11d 10m 44.8s5.93.4"10020.656Aries
UranusJun 1501h 56m 55.8s11d 23m 17.9s5.93.4"10020.488Aries
UranusJun 3001h 58m 56.7s11d 33m 58.0s5.83.5"10020.271Aries
NeptuneJun 0123h 10m 30.0s-06d 20m 10.8s7.92.3"10030.030Aquarius
NeptuneJun 1523h 10m 49.2s-06d 18m 48.1s7.92.3"10029.794Aquarius
NeptuneJun 3023h 10m 43.4s-06d 20m 04.2s7.92.3"10029.550Aquarius