The September night sky

Graphic: Paddy Allen

The month of our autumnal equinox opens with an annular or “ring” solar eclipse on 1 September which is visible along a path that sweeps across Southern Central Africa from Gabon to Madagascar. The surrounding area, where a partial solar eclipse is seen, does not extend as far north as Europe.

A second eclipse occurs on the 16th when the Moon passes through the southern edge of the Earth’s shadow. The resulting penumbral lunar eclipse is already underway as the Harvest Moon rises in the E for western Europe on that evening.

The Moon first touches the shadow at 17:55 BST while still below Britain’s horizon and reaches greatest eclipse at 19:54, 30 minutes or so after moonrise. All but the southern 9% of the lunar disc then lies within the penumbra, but little darkening may be obvious except near its upper edge, closest to the shadow’s dark central umbra. The Moon exits the penumbra at 21:54.

Jupiter remains hidden in the Sun’s glare, but Venus is brilliant in the evening twilight, albeit only 6° high in the W at sunset at present, and no higher in the SW by month’s end.

Easier to spy is the triangle of Mars, Saturn and the star Antares in Scorpius which stands low in the SSW as darkness falls and after Venus sets.

Antares, the dimmest of the three, stands below Saturn while Mars, the brightest, lies to their E (left) and speeds 18° away during the month to approach the lid of the Teapot of Sagittarius, just setting in the SW at our map times. Mars dims from mag -0.3 to 0.1 while Saturn is mag 0.5.

The slender young Moon lies 3° above-left of Venus on the 3rd, and is close to first quarter when it stands a similar distance above-right of Saturn on the 8th and 7° above Mars on the 9th.

Mercury emerges from the Sun’s far side to begin its best morning apparition of 2016 late in the month. Between the 24th to 30th, it brightens from mag 0.5 to -0.6 and rises more than 95 minutes before the Sun to stand 8° or more above the E horizon forty minutes before sunrise. Catch it 1.9° to the left of the very slim earthlit Moon on the 29^th.