It's late summer and astronomically dark skies return to Northumberland for the first time since May. Here's a map of the sky for August showing the moon, stars and planets in the evening sky.
Arcturus and Vega are the first stars to appear after sunset; they are the brightest stars in the northern hemisphere of the sky. Arcturus is a shade brighter than Vega and has an orange hue compared to the pure white of Vega. As the twilight goes on the constellations between those two bright markers - Corona Borealis and Hercules will eventually appear.
The Milky Way runs from northeast to southwest in the sky and is particularly striking as it passes overhead through Cygnus. The three stars marking the Summer Triangle (Vega, Deneb and Altair) are embedded in the Milky Way's faint band of light. Evenings in the second half of August will provide the best chance of seeing the Milky Way before the moon rises. The best views of the Milky Way are obtained with binoculars; try sweeping south from Deneb in Cygnus and south towards Aquila. So many rich fields of stars and star clusters are visible!
Vega is the brightest star in the constellation Lyra (photo, below left). Aside from Vega the four main stars form tiny parallelogram almost overhead at this time of year. There are rich pickings for binoculars and telescopes. At the upper left of the parallelogram is Delta Lyrae (below, middle) - a colourful scattering of stars for binoculars and small telescopes. The most celebrated object in the constellations is the Ring Nebula (M57 - below right) located almost exactly on the line between the two southernmost stars of the parallelogram. Telescopes are needed to see this tiny ring of light and huge telescopes are needed to see the stellar remnant at its centre. There is so much to see in Lyra; I didn't even mention the Double Double - a real test of eyesight and optics!
The huge but fairly obscure pattern of Ophiuchus, the Serpent Bearer, occupies the southern part of the sky. The brightest star in the pattern is 2nd magnitude Rasalhague. Ophiuchus is home to around a dozen bright globular clusters including the Messier objects M10, M12, M14, M19, M62 and M109. The centre of the Milky Way, with its dramatic star fields and curtains of dust spill into the constellation from neighbouring Sagittarius. Unfortunately, this region just skirts the southern horizon in Northumberland and the view is dimmed significantly by the atmosphere. Just above the southwest horizon you might glimpse orange star Antares, the brightest star in Scorpius.
The eastern sky by contrast is quite barren of bright stars. The traditional northern autumn constellations of Pegasus (the winged horse), Andromeda and Perseus are rising in the east during late evening.
Mars and Saturn are visible in the western sky for a short time after sunset. The first quarter moon will be roughly mid-way between the two planets on the evening of August 3rd. Mars and Saturn are roughly equal brightness (magnitudes +0.5 and +0.6 respectively) but Mars has a definite burnt orange colour compared to Saturn's creamy white.
The ice giants Uranus and Neptune are observable later in the evening. Neptune appears as a dim 8th magnitude star in the constellation Aquarius. Larger telescopes at moderate magnification show the pale blue disk of Neptune. The planet Uranus shines like a 6th magnitude star in the constellation Pisces. You might be glimpse the planet with the naked eye from dark sites but binoculars will show it easily.
In the morning sky the planets Venus and Jupiter are converging for a conjunction on August 18th among the stars of Cancer, the Crab. Venus (magnitude -3.9) is much the brighter of the two planets (Jupiter, mag. -1.8). The best time to view from Northumberland will be around 4.30am. Look low towards the eastern horizon to catch the pair.
The full moon on August 10th occurs within hours of lunar perigee (closest point in lunar orbit to the Earth). Such full moons are invariably described in the press as Supermoons. The full moon of August is the biggest and brightest of the year.
If deepsky astronomy is your thing, then the moon will be out of the way on evenings in the second half of August.
The Perseid meteor shower reaches a peak on the night of August 12th-13th. Moonlight will strongly interfere with observed rates this year; only the brightest Perseids will be visible. The best time to observe is during the early hours of August 13th.
The brightest comet during August is expected to be C/2014 E2 Jacques. Comet Jacques is a morning sky object and August will see it moving rapidly north from Auriga, through Perseus, Cassiopeia and into Cepheus. Small telescopes will be enough to detect it. The presence of moonlight around the middle of the month will make observation difficult. The chart below shows the position of the comet during August (with the magnitude shown).
A complete list of currently observable comets can be found here.
Dr Adrian Jannetta
Guitar strummin' explorer of the universe. Mild mannered maths teacher by day and astronomer by night.