Mercury passed through superior conjunction during the second half of last month. The fast-moving planet reappears at the beginning of this month, low down towards the west after sunset. It remains visible throughout June, reaching its highest altitude above the horizon at greatest elongation east on June 23rd. During the visibility period Mercury dims in brightness. On June 1st, it shines at magnitude -1.1. By June 15th, it has reduced to magnitude -0.1 and by month end magnitude +0.9. Its angular size increases from 5.5 to 9.2 arc seconds during June.
On June 18th, Mercury passes just 1/5 of a degree north of fainter Mars (mag. +1.8). It's worth comparing the colour similarity of the two planets.
Venus, mag. -3.8, remains a morning object throughout June. However, the planet is now closing in on superior conjunction, which it attains in August. From southern locations, Venus rises 90 minutes before the Sun on the first day of the month. However, by month's end it rises only 50 minutes before the Sun. For northern based observers, the visibility period is even shorter.
On June 1st, the waning crescent Moon passes 3 degrees south of Venus.
Mars remains visible as an early evening object in western twilight throughout June, although from mid-latitude northern locations it will become increasingly difficult to spot during the second half of the month. The Red planet sets about 2 hours after the Sun at month's start, reducing to about an hour or less by month's end. Mars is long past its best and shines at only magnitude +1.8 with an apparent diameter of less than 4 arc seconds. Initially found in Gemini, it moves into Cancer on June 28th.
On June 5th, the waxing crescent Moon passes a couple of degrees south of the Moon. As previously mentioned, Mercury passes close by Mars on the 18th.
The highlight of the month occurs on June 10th, when Jupiter reaches opposition. On this day, the gas giant will be located 4.284 AU (approx. 641 million kilometres or 398 million miles) from Earth. Jupiter is currently moving retrograde in Ophiuchus. At magnitude -2.6 it's unmistakable and easily brighter than any nighttime star. Jupiter's apparent size is about 46 arc seconds. This month, the planet is visible all night long, rising in the east at sunset, reaching its highest point in the sky around midnight before setting in the west at sunrise. Due to its southerly declination, Jupiter is much better placed from observers located at southern and equatorial latitudes.
Popular 7x50 or 10x50 binoculars reveal Jupiter as a very small pale disk. Also visible are the large Galilean moons (Io, Europa, Ganymede and Callisto), which continuously change position as they orbit the planet. Through small scopes, details such as the great equatorial belts and shadow transits of the moons can be observed. Larger scopes reveal the "Great Red Spot" and other cloud details.
On June 16th, the almost full Moon passes a couple of degrees north of Jupiter.
Saturn, moving retrograde in Sagittarius, is now well placed for observation. From temperate southern latitudes, the magnificent ringed planet rises before 8pm at the beginning of June and a full two hours earlier by month's end. Like Jupiter, Saturn is currently better seen from southern rather than northern locations. From northern temperate locations, the planet can be seen up to 3 hours later.
When seen through a telescope, Saturn is a stunning sight. A small 80mm (3.1-inch) refractor easily reveals the ring system, which is currently wide open at a tilt of 25 degrees to the line of sight. A 150mm (6-inch) or 200mm (8-inch) reflector shows a wealth of details, such as planetary cloud formations, ring divisions and up to half a dozen satellites. During the month, the magnitude of Saturn increases marginally from +0.2 to +0.1 with its apparent diameter improving slightly from 18.0 to 18.4 arc seconds.
Uranus, mag. +5.9, is located in Aries. For northern temperate observers, at the beginning of the month the planet should be visible with binoculars and small scopes, above the eastern horizon, an hour or so before sunrise. By months end it rises over three hours before the Sun. Observers located further south have it better with Uranus visible for considerably longer.
The waning crescent Moon passes 5 degrees south of Uranus on June 27th.
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 25 degrees south of the Great Square of Pegasus. The planet is positioned a couple of degrees northwest of star phi Aquarii (φ Aqr - mag. +4.2).
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 21st, Neptune reaches its first stationary point, which signals the beginning of this year's opposition period. The planet then commences retrograde motion. Later, on June 24th, the waning gibbous Moon passes 4 degrees south of Neptune.
Solar System Data Table - June 2019
|Date||Right Ascension||Declination||Mag.||App. Size||Illum. (%)||Dist. (AU)||Constellation|
|Sun||Jun 01||04h 33m 22.6s||21d 56m 39.8s||-26.7||31.5'||100||1.014||Taurus|
|Sun||Jun 15||05h 31m 09.7s||23d 16m 16.6s||-26.7||31.5'||100||1.016||Taurus|
|Sun||Jun 30||06h 33m 29.4s||23d 12m 48.1s||-26.7||31.5'||100||1.017||Gemini|
|Mercury||Jun 01||05h 26m 00.3s||25d 00m 07.8s||-1.1||5.5"||87||1.231||Taurus|
|Mercury||Jun 15||07h 12m 08.0s||24d 12m 38.2s||-0.1||6.8"||56||0.983||Gemini|
|Mercury||Jun 30||08h 15m 30.5s||19d 05m 56.1s||0.9||9.2"||29||0.732||Cancer|
|Venus||Jun 01||03h 11m 18.2s||16d 29m 11.4s||-3.8||10.5"||94||1.588||Aries|
|Venus||Jun 15||04h 21m 08.7s||20d 39m 56.2s||-3.8||10.2"||96||1.638||Taurus|
|Venus||Jun 30||05h 39m 29.6s||23d 07m 35.3s||-3.9||9.9"||98||1.680||Taurus|
|Mars||Jun 01||06h 43m 42.3s||24d 12m 59.4s||1.8||3.9"||98||2.428||Gemini|
|Mars||Jun 15||07h 22m 39.5s||23d 15m 47.9s||1.8||3.8"||98||2.497||Gemini|
|Mars||Jun 30||08h 03m 25.1s||21d 37m 02.4s||1.8||3.7"||99||2.560||Cancer|
|Jupiter||Jun 01||17h 18m 30.7s||-22d 29m 30.3s||-2.6||45.8"||100||4.302||Ophiuchus|
|Jupiter||Jun 15||17h 10m 51.5s||-22d 22m 50.1s||-2.6||46.0"||100||4.285||Ophiuchus|
|Jupiter||Jun 30||17h 03m 02.0s||-22d 15m 10.3s||-2.6||45.5"||100||4.330||Ophiuchus|
|Saturn||Jun 01||19h 23m 59.6s||-21d 39m 53.6s||0.2||18.0"||100||9.249||Sagittarius|
|Saturn||Jun 15||19h 20m 40.6s||-21d 47m 19.7s||0.1||18.2"||100||9.124||Sagittarius|
|Saturn||Jun 30||19h 16m 19.9s||-21d 56m 36.9s||0.1||18.4"||100||9.047||Sagittarius|
|Uranus||Jun 01||02h 09m 13.5s||12d 31m 33.5s||5.9||3.4"||100||20.660||Aries|
|Uranus||Jun 15||02h 11m 42.2s||12d 44m 19.3s||5.9||3.4"||100||20.503||Aries|
|Uranus||Jun 30||02h 13m 54.2s||12d 55m 28.2s||5.8||3.5"||100||20.297||Aries|
|Neptune||Jun 01||23h 18m 42.2s||-05d 31m 56.1s||7.9||2.3"||100||30.067||Aquarius|
|Neptune||Jun 15||23h 19m 05.6s||-05d 30m 06.7s||7.9||2.3"||100||29.832||Aquarius|
|Neptune||Jun 30||23h 19m 04.5s||-05d 30m 55.4s||7.9||2.3"||100||29.585||Aquarius|