The Evening Sky in August 2017

Download a PDF containing this chart, additional charts for specific areas of the sky and descriptions of interesting objects visible at this time of year.

The Evening Sky in August 2017

Three naked-eye planets are visible in the early evening sky for most of the month. Jupiter is northwest of overhead, the brightest 'star' in the sky. Saturn is northeast of overhead, the brightest 'star' in its part of the sky but fainter than Jupiter. Above Saturn is orange Antares. Mercury is low in the west, above the sunset point, for the first half of the month before disappearing in the twilight.

Bright stars are widely scattered over the sky. Vega on the north skyline is balanced by Canopus low in the south. Orange Arcturus is in the northwest, twinkling red and green as it sets. The Southern Cross, Crux, and the Pointers are midway down the southwest sky. The Milky Way spans the sky from northeast to southwest.

Jupiter, high in the west and golden-coloured, sets steadily earlier through the month: at 11 pm at the start of August and after 9 pm at the end. Saturn, cream-coloured, stays in the sky most of the night, setting in the southwest in the morning hours. Jupiter and Saturn are both well placed for evening viewing in a telescope. Any small telescope will show the four 'Galilean' moons of Jupiter, though not every night as the moons can disappear behind Jupiter or hide in its shadow. Saturn's ring is visible in any telescope magnifying 20x or more. Jupiter is 890 million km away and Saturn 1400 million km away mid-month. The Moon appears close to Saturn on the 3rd and passes Jupiter on the 25th and 26th.

Mercury (not shown on the chart) ends its evening sky appearance as it passes between the Earth and the Sun. It sets before 8 pm at the beginning of the month, the brightest 'star' in the lower western sky. By the 20th it is setting before 7 pm, an hour after the Sun, and fading. It disappears soon after.

Midway down the southwest sky are 'The Pointers ', Beta and Alpha Centauri. They point down and rightward to Crux the Southern Cross. Alpha Centauri is the third brightest star and the closest of the naked eye stars, 4.3 light years* away. Beta Centauri, like most of the stars in Crux, is a blue-giant star hundreds of light years away and thousands of times brighter than the sun.

Antares marks the body of the Scorpion. The Scorpion's tail hooks around the zenith like a back-to-front question mark. Antares and the tail make the 'fish-hook of Maui' in Maori star lore. Antares is a red giant star: 600 light years away and 19 000 times brighter than the sun. Below or right of the Scorpion's tail is 'the teapot' made by the brightest stars of Sagittarius. It is upside down in our southern hemisphere view.

The Milky Way is brightest and broadest overhead in Scorpius and Sagittarius. In a dark sky it can be traced down past the Pointers and Crux into the southwest. To the northeast it passes Altair, meeting the skyline right of Vega. The Milky Way is our edgewise view of the galaxy, the pancake of billions of stars of which the sun is just one. The thick hub of the galaxy, 30 000 light years away, is in Sagittarius. The actual centre is hidden by dust clouds in space. The nearer dust clouds appear as gaps and slots in the Milky Way. Binoculars show many clusters of stars and some glowing gas clouds in the Milky Way.

The Large and Small Clouds of Magellan LMC and SMC look like two misty patches of light low in the south, easily seen by eye on a dark moonless night. They are galaxies like our Milky Way but much smaller. The LMC is about 160 000 light years away; the SMC about 200 000 light years away.

Brilliant Venus rises in the northeast after 5 a.m. all month. It is bright enough to cast shadows in dark locations. The Moon is above Venus at dawn on the 19th. By mid-morning the two will be due north and level, with Venus on the right. Once the Moon is found, one can then see the planet in daylight by eye.

The Moon grazes the Earth's shadow on the morning of the 8th. The top of the Moon will begin to darken around 5 a.m. By 6:20 the top quarter of the Moon will be in shadow. Moonset is soon after.

A total solar eclipse crosses the United States on the 22nd NZST. Nothing is seen from New Zealand.

*A light year (l.y.) is the distance that light travels in one year: nearly 10 million million km or 1013 km. Sunlight takes eight minutes to get here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes four years to reach the nearest star, Alpha Centauri.

Newsletter editor:

Alan Gilmore Phone: 03 680 6817
P.O. Box 57 Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Lake Tekapo 7945
New Zealand