Night Sky Guide for June 2018

The summer of 2018 in the northern hemisphere will officially begin on June 21 with June Solstice at 09:54 UTC. On this day, Earth's North Pole will be tilted toward the Sun, which will have reached its northernmost position in the sky and will be directly over the Tropic of Cancer at 23.44 degrees north latitude. In the southern hemisphere, the Sun is above the horizon for less time than on any other day of the year and astronomers define this day to be the first day of winter.

The Moon will be located on the same side of the Earth as the Sun on June 14 – New Moon – and will not be visible in the night sky. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.

The Moon will reach its full phase at 04:54 UTC on June 28.

• June 2 – M13 well placed for observation. The Hercules globular cluster (M13, NGC 6205) will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +36°27', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 33°S. At magnitude 5.8, M13 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• June 3 – Close approach of the Moon and Mars – 10:56 UTC. The Moon, 19 days old, and Mars will make a close approach, passing within 3°07' of each other. The Moon will be at mag -12.3, and Mars at mag -1.3, both in the constellation Capricornus. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars. At around the same time, the two objects will also share the same right ascension – called a conjunction.

• June 3 – Conjunction of the Moon and Mars – 12:01 UTC. The Moon and Mars will share the same right ascension, with the Moon passing 3°09' to the north of Mars. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -12.3, and Mars at mag -1.3, both in the constellation Capricornus. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• June 3 – M12 well placed for observation. The globular cluster M12 (NGC 6218) in Ophiuchus will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -01°56', it is visible across much of the world; it can be seen at latitudes between 68°N and 71°S. At magnitude 6.1, M12 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• June 5 – M10 well placed for observation. The globular cluster M10 (NGC 6254) in Ophiuchus will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -04°05', it is visible across much of the world; it can be seen at latitudes between 65°N and 74°S. At magnitude 5.0, M10 is too faint to be seen with the naked eye from any but the very darkest sites but is visible through a pair of binoculars or a small telescope.

• June 6 – Mercury at superior solar conjunction – 01:50 UTC. Mercury will pass very close to the Sun in the sky as its orbit carries it around the far side of the solar system from the Earth. This occurs once in every synodic cycle of the planet (116 days) and marks the end of Mercury's apparition in the morning sky and its transition to become an evening object over the next few weeks. At closest approach, Mercury will appear at a separation of only 0°44' from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare. Mercury will also pass apogee – the time when it is most distant from the Earth – at around the same time, since it will lie exactly opposite to the Earth in the Solar System. It will move to a distance of 1.32 AU from the Earth, making it appear small and very distant. If it could be observed, it would measure 5.1 arcsec in diameter, whilst appearing completely illuminated.

• June 10 – M92 well placed for observation. The globular cluster M92 (NGC 6341) in Hercules will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +43°08', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 26°S. At magnitude 6.5, M92 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• June 13 – New Moon – 19:45 UTC. The Moon will be located on the same side of the Earth as the Sun and will not be visible in the night sky. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.

• June 15 – NGC 6388 well placed for observation. Across much of the world, the globular cluster NGC 6388 in Scorpius will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -44°44', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 25°N. At magnitude 6.9, NGC6388 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• June 16 – Close approach of the Moon and Venus – 12:40 UTC. The Moon, 3 days old, and Venus will make a close approach, passing within 2°18' of each other. The Moon will be at mag -10.3, and Venus at mag -4.0, both in the constellation Cancer. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars. At around the same time, the two objects will also share the same right ascension – called a conjunction.

• June 16 –  Conjunction of the Moon and Venus – 13:13 UTC. The Moon and Venus will share the same right ascension, with the Moon passing 2°20' to the south of Venus. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -10.3, and Venus at mag -4.0, both in the constellation Cancer. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• June 16 – Close approach of the Moon and M44 – 19:50 UTC. The Moon and M44 will make a close approach, passing within 1°10' of each other. The Moon will be at mag -10.5, and M44 at mag 3.1, both in the constellation Cancer. The pair will be too widely separated to fit within the field of view of a telescope but will be visible through a pair of binoculars.

• June 16 – M6 well placed for observation. Across much of the world, the butterfly open star cluster (M6, NGC 6405) in Scorpius will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -32°15', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 37°N. At magnitude 4.2, M6 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

• June 18 – IC4665 well placed for observation. The open star cluster IC 4665 in Ophiuchus will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +05°38', it is visible across much of the world; it can be seen at latitudes between 75°N and 64°S. At magnitude 4.2, IC4665 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

• June 20 – Close approach of Venus and M44 – 10:41 UTC. Venus and M44 will make a close approach, passing within 0°42' of each other. Venus will be at mag -4.0, and M44 at mag 3.1, both in the constellation Cancer. The pair will be a little too widely separated to fit comfortably within the field of view of a telescope but will be visible through a pair of binoculars.

• June 20 – M7 well placed for observation. Across much of the world, the Ptolemy cluster (M7, NGC 6475) in Scorpius will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -34°47', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 35°N. At magnitude 3.3, M7 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

• June 21 – June Solstice – 09:54 UTC. The North Pole of the Earth will be tilted toward the Sun, which will have reached its northernmost position in the sky and will be directly over the Tropic of Cancer at 23.44 degrees north latitude. This is the day of the year when the Sun's annual passage through the constellations of the zodiac carries it to its most northerly point in the sky. On this day, the Sun is above the horizon for the longer than on any other day of the year in the northern hemisphere. This is counted by astronomers to be the first day of summer. In the southern hemisphere, the Sun is above the horizon for less time than on any other day of the year and astronomers define this day to be the first day of winter.

• June 23 – Conjunction of the Moon and Jupiter – 18:47 UTC. The Moon and Jupiter will share the same right ascension, with the Moon passing 4°13' to the north of Jupiter. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -12.3, and Jupiter at mag -2.4, both in the constellation Libra. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• June 23 – Close approach of the Moon and Jupiter – 21:17 UTC. The Moon and Jupiter will make a close approach, passing within 4°01' of each other.

• June 23 – NGC well placed for observation. Across much of the world, the open star cluster NGC 6530, close to the lagoon nebula (M8) in Sagittarius will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -24°21', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 45°N. At magnitude 4.6, NGC6530 is too faint to be seen with the naked eye from any but the very darkest sites but is visible through a pair of binoculars or a small telescope.

• June 23 – NGC 6541 well placed for observation. Across much of the world, the globular cluster NGC 6541 in Corona Australis will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -43°42', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 26°N. At magnitude 7.3, NGC6541 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• June 27 – Saturn at opposition – 13:15 UTC. Saturn will be well placed for observation, in the constellation Sagittarius. It will be visible for much of the night, reaching its highest point in the sky at around midnight local time. It will be brighter than any other time of the year and will be visible all night long. This is the best time to view and photograph Saturn and its moons. A medium-sized or larger telescope will allow you to see Saturn's rings and a few of its brightest moons.

• June 27 – Conjunction of the Moon and Saturn – 03:43 UTC. The Moon, 15 days old, and Saturn will share the same right ascension, with the Moon passing 1°46' to the north of Saturn. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -12.5, and Saturn at mag 0.0, both in the constellation Sagittarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• June 27 – Close approach of the Moon and Saturn – 03:51 UTC. The Moon and Saturn will make a close approach, passing within 1°46' of each other. 

• June 28 – Full Moon – 04:54 UTC. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This full moon was known by early Native American tribes as the Full Strawberry Moon because it signaled the time of year to gather ripening fruit. It also coincides with the peak of the strawberry harvesting season. This moon has also been known as the Full Rose Moon and the Full Honey Moon.

• June 27 – NGC 663 well placed for observation. The open star cluster NGC 6633 in Ophiuchus will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +06°30', it is visible across much of the world; it can be seen at latitudes between 76°N and 63°S. At magnitude 4.6, NGC6633 is too faint to be seen with the naked eye from any but the very darkest sites but is visible through a pair of binoculars or a small telescope.

Video courtesy Hubble Space Telescope

Sources: In The Sky by Dominic Ford, NASA, The Watchers

Featured image credit: TW