The Planets this Month - June 2016

Mercury

Mercury reaches greatest elongation on June 5th when it's positioned 24.2 degrees west of the Sun. Despite this at northern latitudes the angle of the ecliptic is unfavourable and the planet will be challenging to spot low down above the eastern horizon. However it's a different story from the Southern Hemisphere where elusive Mercury puts on a respectable morning show for the first three weeks of the month. During week one it rises more than two hours before the Sun and can be seen 10 degrees above the east-northeastern horizon an hour before sunrise. After that Mercury slips back towards the Sun until it's finally lost to the bright twilight during the last week of June. It should be noted that the planet gains in brightness from mag. +0.8 to -1.0 during the visibility period.

On June 3rd, the thin waning crescent Moon passes 0.7 degrees south of Mercury (mag. +0.5) with an occultation visible from southern Africa and Madagascar (9:47 UT).

Venus

Venus reaches superior conjunction on June 6th. Since the planet is currently located on the far side of the Sun it's not suitably placed for observation. Indeed from June 5th to June 7th, Venus passes directly behind the Sun as seen from Earth. This "occultation" lasts some 46 hours and for its duration no Earth based instrument will be able to detect the planet.

At conjunction Venus and the Earth are separated by 1.74 AU (260 million kilometers or 161 million miles).

Mars

Mars is just past opposition and remains well situated for observation throughout June. The "Red planet" is visible after sunset and remains so until the early hours of the morning. It's better placed from tropical and southern latitudes where it appears higher in the sky and has a longer visibility period than at mid-northern latitudes. Although still shining brightly it does fade from mag. -2.0 to -1.4 as the month progresses.

Mars starts the month moving retrograde among the faint stars of Libra. On the last day of June it reaches its second stationary point, which is often regarded as the end of the opposition period, thereafter direct motion is once again resumed.

The apparent size of the planet decreases from 18.6 to 16.5 arc seconds this month but remains large enough that major surface details such as the Polar Cap and Syrtis Major are visible even with a small scope. On initial observation the surface may appear bland but with patience it's possible to tease out subtle details. Also don't be afraid to push up the magnification, Mars will take it.

The surrounding region of sky also contains Saturn (mag. 0.0) about 15 degrees east of Mars and first magnitude red supergiant star Antares (α Sco - mag. +1.0) approx. 15 degrees to the southeast. Of the three objects Mars is the brightest followed by Saturn then Antares.

On June 17th the waxing gibbous Moon passes 7 degrees north of Mars.

Mars and Saturn during June 2016 - pdf format (credit:- freestarcharts)

Jupiter

Although now fading Jupiter remains visible as a brilliant evening object towards the west as soon as it's dark enough. However the planet's visibility is reducing and by June 30th it sets before midnight from northern temperate latitudes and slightly earlier for those living further south. During the month, Jupiter continues its direct eastwards motion among the faint stars of Leo, some way south of the main constellation pattern.

As the month progresses, Jupiter fades from mag. -2.0 to -1.9 with its apparent size decreasing from 37 to 34 arc seconds. On June 11th the waxing crescent Moon passes 1.5 degrees south of Jupiter offering a nice early evening pairing.

Jupiter during June 2016 - pdf format (credit:- freestarcharts)

Saturn

Saturn, mag. 0.0, reaches opposition in Ophiuchus on June 3rd. The famous "Ringed planet" is visible all night long and at its best for the year. With a declination of -20.5 degrees it's much better placed from southern and tropical locations where it appears higher in the sky and has a longer visibility period than from northern temperate latitudes.

At opposition, Saturn is located 9.015 AU (1349 million kilometres or 838 million miles) from Earth. Even a small telescope will show its most famous feature, the spectacular rings. Also visible is the largest and brightest moon of Saturn, eighth magnitude Titan which can be seen with binoculars. Small scopes will also show additional moons including Rhea, Tethys and Dione.

A good opportunity exists this month to spot bizarre moon Iapetus. This world is famous for its "two-tone" colouration with one side being much darker in colour than the other. As a result when Iapetus is positioned on the western side of Saturn (when viewed from Earth) it appears brighter than from the opposite side. This happens on June 22nd with Iapetus peaking at mag. +10.1 and easily within the range of small scopes.

Before that on June 19th, the full Moon passes 3 degrees north of Saturn.

Uranus

Uranus, mag. +5.9, is now a morning object in Pisces. For northern temperate observers the planet is swamped by the bright early morning twilight sky for most of June. Nevertheless, towards the end of the month it can be seen with binoculars and small scopes above the eastern horizon an hour or so before sunrise.

Observers located further south have it much better with Uranus well placed in the morning sky throughout June. At the beginning of the month it rises some 4 hours before the Sun improving to before midnight by months end.

On June 1st and 28th, the waning crescent Moon passes a couple of degrees south of Uranus.

Uranus during June 2016 - pdf format (credit:- freestarcharts)

Neptune

Neptune shines at mag. +7.9 and is now well placed for observation in Aquarius. By months end the most distant planet rises around midnight from northern temperate latitudes but much earlier for those located further south. It's positioned about 30 degrees south of the Great Square of Pegasus. Locating Neptune is easy at the moment since star lambda Aqr (λ Aqr - mag. +3.7) is just 0.5 degrees northwest of the planet. Neptune is the only planet that's not visible to the naked eye but it can be readily seen with binoculars and small telescopes.

On June 14th, Neptune reaches its first stationary point signaling the beginning of this year's opposition period. The planet then commences retrograde motion. Later on the 26th the waning gibbous Moon passes close by Neptune with an occultation visible from central and Northern Europe (0 UT).

Neptune during June 2016 - pdf format (credit:- freestarcharts)

Solar System Data Table June 2016