Outstanding Jupiter in closest opposition for 47 years

Indeed, while the nights are growing longer and before the cold of winter sets in, this is perhaps the best time of the year for any novice stargazer to take their first steps.

Our star charts depict the sky while facing north and south at the times given. The semicircular border of each chart represents the line that stretches overhead from east to west, while the lower straight borders mark the horizon.

Overhead, the zenith, is at the top of each semicircle and the bright star closest to the zenith at our map times is Deneb in Cygnus the Swan. Once upon a time, these charts were printed so that the starry detail was in white against a black background, but our current "negative" scheme (black stars against a white sky) makes the detail stand out better. Of course, you'll be hard pressed to spot the labels or the constellation-lines in the real sky!

If we watch the sky for any length of time, we soon realise that the stars appear to move as the Earth turns on its axis. Those in the south drift from east to west, while those in the north turn counterclockwise about the star Polaris, the Pole Star that just happens to lie overhead to the Earth's North Pole. Find Polaris by extending a line upwards through the two right-hand stars, the Pointers, of the Plough, which is distinctive in our north-western evening sky at present.

Although Deneb is the closest star to the zenith at our map times, it is the brighter Vega in Lyra which stands closer to overhead at nightfall.

Together with Altair in Aquila, in the middle of our southern sky, these form the "asterism" called the Summer Triangle. Asterisms are unofficial star patterns that come in all shapes and sizes; some, such as the Triangle, take in several constellations, while others are too small and compact to be seen without a telescope. The diffuse band of the Milky Way flows through the Summer Triangle as it arches overhead at our map times from the south-west to the north-east, though its countless distant stars may well be swamped by light pollution for many of us.

Another asterism, this of not-so-bright stars, is the Square of Pegasus, which climbs in the east during the evening. South of the Square, and outshining every star, is the giant planet Jupiter, which comes to opposition on the 21st when it stands opposite the Sun in the sky at its closest and brightest.

Indeed, Jupiter comes within 591.5 million km, marginally closer than at any opposition since 1963, and is conspicuous and unmistakable as it climbs from low in the east as the sky darkens to pass due south and 32 high as seen from Edinburgh three hours later.

Jupiter is magnitude -2.9 and its huge gaseous globe, 142,984 km wide, appears 50 arcseconds across through a small telescope. This is 1/36th as wide as the full Moon, but easily large enough for its interesting cloud bands to be seen. Another flash in those clouds, probably the fireball caused by the impact of a small asteroid or comet, was observed and videoed by amateur astronomers on 20 August, suggesting that such collisions are less rare than was thought.

Binoculars are all we need to spot the four main moons of Jupiter, lined up to either side of the disk, while binoculars will also show the planet Uranus in the same field of view. In fact, Uranus is 2,300 million km beyond Jupiter and shines at magnitude 5.7, close to the naked-eye brightness limit.

A decent telescope shows its 51,118 km globe as a tiny blue-green disk only 4 arcseconds wide. As both Jupiter and Uranus creep westwards at different rates against the stars of Pisces, their relative positions change - Uranus lies 1.7 west (right) of Jupiter tonight, 0.8 north-north-west of Jupiter on the 18th and 1.4 north-east of Jupiter on the 30th. Remember that 1 corresponds to two Moon-widths.

The Sun moves almost 12 southwards during September to cross the celestial equator at 04:09 BST on the 23rd, the moment of the autumnal equinox. Sunrise/sunset times for Edinburgh change from 06:17/20:08 BST on the 1st to 07:13/18:51 on the 30th, while nautical twilight shrinks in duration from 89 to 80 minutes. The Moon is at last quarter tomorrow, new on the 8th, at first quarter on the 15th, and full (the Harvest

Moon) when it is close to Jupiter on the 23rd.

Mercury passes around the Sun's near side on Friday and then moves to stand 18 west of the Sun on the 19th during its best morning appearance of the year. Between the 13th and the month's end, it rises more than 80 minutes before the Sun and stands 7 to 10 high and almost due east thirty minutes before sunrise. The small innermost planet brightens from magnitude 1.1 to -1.1 during this spell, becoming an easy naked eye object if our eastern horizon is clear.

We should probably forget about the other naked-eye planets. Venus, brilliant at magnitude -4.4, is only 4 above Edinburgh's west-south-western horizon at sunset on the 1st, but sets with the Sun later in the month. Mars and Saturn are not far away in the sky, but much too faint at magnitudes 1.5 and 1.0 to be seen in our bright twilight.