Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during July 2014.

The star Arcturus, in the constellation of Bootes, is setting in the west around midnight. The circlet of stars called Corona Borealis is up to its left, with Hercules higher up still. Continuing around the sky, the bright star Vega appears in Lyra the Lyre. Deneb, in Cygnus the Swan, is up to its left, and the five brightest stars of Cygnus can be seen to form a cross known as the Northern Cross. The lowest and faintest of these, Albireo, is revealed to be a double star of blue and gold colours when observed with a telescope. Coming down through the constellations of Vulpecula and Sagitta, we reach Aquila the Eagle and its bright star, Altair. The three stars of Vega, Deneb and Altair comprise the Summer Triangle. Below this, in the constellations of Serpens Caput, Ophiuchus and Serpens Cauda, Sagittarius is lying in the south. It contains the asterism of the Teapot, which is home to many star clusters and nebulae. The tiny constellation of Delphinus the Dolphin is to the lower left of Cygnus and Lyra.

The Planets

• Jupiter reaches conjunction (behind the Sun in the sky) on the 24th, and so is only visible for the first week of July, low in the west.
• Saturn is in Libra, near the wide double star Alpha Librae. It dims from +0.4 to +0.5 during the month, and reverses direction as its retrograde (westward) motion ends on the 21st. The rings are at 21 degrees to the line of sight, but the planet remains at a low elevation for northern hemisphere observers.
• Mercury appears before dawn, lying to the lower left of Venus for much of the month. It reaches western elongation (furthest from the Sun in the sky) on the 12th, when it has a magnitude of +0.4 and a presents a half-full disc. It appears lower in the east at dawn later in July, but brightens to magnitude -1.4 by month's end.
• Mars lies close to the star Spica, in Virgo, and is just 1.3 degrees away on the 13th. It shrinks from 9.5 to 7.9" in angular diameter during July, and dims from magnitude 0 to +0.4. It is already low in the west at nightfall, but larger surface features, such as Syrtis Major, may be spotted through a telescope.
• Venus rises in the east-north-east at morning twilight, and is 20 degrees above the horizon at sunrise. It decreases in angular size from 12 to 11" over the month as it moves away from the Sun, but the illumination of its gibbous disc increases from 85 to 92 percent over the same period, so its brightness drops only slightly, from magnitude -0.9 to -0.8. Venus is close to Aldebaran, in Taurus, in the first few days of the month.

Highlights

• Saturn is still nice to observe this month. It can be found by following the Plough's handle down past Arcturus to the bright white star Spica, then looking for the slightly brighter, yellower object to its lower left.
• The globular cluster M13 is high in the sky this month. It is two-thirds of the way up the right-hand side of the Keystone asterism in Hercules, appearing as a fuzzy glow in binoculars and a spherical concentration of stars in a telescope. Nearby, the multiple star system Epsilon Lyrae is to the left of Vega in Lyra. It looks like a double star in binoculars, but a telescope shows a pair of doubles, giving rise to the nickname of the Double Double.
• Noctilucent clouds may be observed early in the month. They can be seen in the north during deep twilight and are 80 kilometres above the Earth, allowing them to be illuminated by the already-set Sun while lower clouds are in shadow.
• Mars lies between Spica and a first-quarter Moon in the south-west after sunset on the 5th.
• The two brightest asteroids, Vesta and Ceres, can be found using binoculars after sunset on the 5th and 6th. They are only 10' apart in Virgo and have magnitudes of +7.2 and +8.5 respectively, the former being smaller but also closer and more reflective.
• Saturn and a gibbous Moon are close together an hour after sunset on the 7th.
• Venus is 4.5 degrees to the lower-left of a thin crescent Moon before dawn on the 24th, with Mercury 8 degrees further to the lower-left, near the eastern horizon.