The Night Sky This Month: June 2015

Alpine Valley
The Alpine Valley shot by the Lunar Reconnaissance Orbiter. Credit: NASA/GSFC/Arizona State University, Virtual Moon Atlas.

The month of June offers stargazers excellent viewing with binoculars and telescopes of all apertures, as well as also presenting opportunities for naked eye planetary observations. One of the most spectacular sights during June is the race between two planets, Venus and Jupiter, which is always special since it demonstrates their motions within the solar system more clearly than almost anything else, but more about that in a moment.

Mercury

Mercury attains maximum elongation west of the Sun on June 24, and at magnitude +0.5, and a phase of approximately 35% illumination, should be visible in binoculars slightly above the horizon in the north east shortly before dawn. However, June is not the best month for observing Mercury, and care must be taken to use suitable filters on all viewing equipment to avoid eye injuries should the Sun suddenly come into view.

Mars

Mars is at superior conjunction on June 14, which means that it will be shielded by the Sun, and thus not visible for the entire month of June.

Venus and Jupiter

Throughout June, Venus will race through the sky from Cancer to Leo to approach Jupiter, that will also be traversing the constellation of Leo in the direction of Regulus. Of note is the fact that on June 30, the planets will be within 21 arc minutes of one other, with Jupiter almost completely illuminated.  Venus will however only be visible as a crescent, with only 34% of its disc illuminated. The pair will dominate the area low on the horizon in the west-northwest for about an hour before setting at around 23:30 GMT. On June 12-13, Venus will also be passing closely by M44 (Beehive Cluster) in Cancer just after sunset.

Saturn

The ringed planet will be visible shortly after sunset on June 28, close to the waxing gibbous Moon. The Moon will be 88% illuminated, with a separation from Saturn of about 10 when both set at about 01:30 GMT the next morning. Find Saturn in Libra by following the handle of the Plough towards Arcturus, then down towards 1st magnitude Spica in Virgo. Saturn will appear as a fat, yellow star marginally brighter than Spica, which is white. Telescopes of modest aperture, as well as mounted binoculars will show Titan, the planet’s most luminous moon while instruments of 6-8 inches aperture at magnifications of about 200 will show the ring system in rich detail, provided the seeing is good.

The Moon

On June 25 and 26, the Moon offers a spectacular view of the Alpine Valley, which is a cleft across the Appenine mountain chain, which in turn forms the edge of the Mare Imbrium. Even telescopes of modest aperture will reveal this 7 mile-wide and 79 mile-long valley in stunning detail, although the rille that runs almost the length of the valley can be challenging to view in small instruments. The following two nights offer views of Plato, a dark crater, as well as the young Copernicus crater. Phases of the moon during July are as follows: New Moon (16th), First Quarter (24th), Full moon (2nd), Last Quarter (9th)

Noctilucent CloudsNoctilucent Clouds

June will offer several occasions to see these “clouds that shine at night”. These clouds are also known as “polar mesospheric clouds”, and are not visible during the day because of their great height, occurring anywhere from 45-50 miles above sea level. The only time to see them is during deep twilight when the Sun illuminates them from below the horizon, while the rest of the atmosphere is in deep shadow.  Interestingly, this type of cloud is one of the least understood phenomena in the atmosphere, and it is widely thought that their increasing occurrence and density may be a visible manifestation of the effects of climate change. Look for these nebulous clouds in the north after sunset.

Deep Sky Objects

Two particularly beautiful binocular objects during June are M13 (a globular cluster) in Hercules, and two orbiting binary systems in Lyra. To find M13, look two-thirds up the right hand leg of the asterism that makes up the “keystone” in Hercules. M13 is without doubt the prettiest globular star cluster in the entire Northern sky. The other object can be found just left of Vega, in the constellation of Lyra. Viewed through binoculars however, Epsilon Lyrae appears to be a run of the mill binary system, but a telescope resolves the object as two binary star systems orbiting each other, from whence the name Double-Double, as it is also known.

The Lyrid Meteor Shower

The Lyrids reach their peak on 15/16 June after dark, with a frequency of about 8 meteors p/h coming from the direction of Vega. The relative paucity of meteors is compensated for by the young Moon, which makes it possible to the see the few meteors that might be visible. There is some doubt whether the Lyrids still exist as legitimate meteor shower because of the rapid decline in meteor numbers after the 1960’s, but if the seeing is good, it might be worth the trouble to see if any still exist.

Observing in June

The few examples of easily viewable objects during June represents only a very small sample of what can be viewed, but unstable atmospheric conditions in many parts of the country during summer can seriously hamper seeing conditions. Nevertheless, any opportunity to observe the heavens is a good opportunity, so get out there, and observe!