Dundee Astro - Sky Notes

October 1st    sunrise     7.15 am BST   sunset     6.46 pm BST
October 15th sunrise    7.44 am BST    sunset     6.09 pm BST
October 31st sunrise     7.18 am GMT sunset     4.31 pm GMT

In mid-October, the sky is reasonably dark between 7.30 pm and 6.30 am BST.
The Sun lies in the constellation of Virgo, the Virgin, at the start of October and remains there for almost the entire month; it crosses into Libra, the Scales, on the last day of the month, Friday 31st.
British Summer Time (BST) ends on Sunday 26th October; clocks should be put back one hour to read Greenwich Mean Time (GMT).

The sunrise, sunset and twilight times given here are for Dundee but generally apply across central Scotland.

At the start of October the waxing gibbous Moon is low in the south in the evening twilight. On the night of Sunday 5th the almost full Moon lies just to the upper right of the planet Saturn.
Full Moon falls early on the morning of Tuesday October 7th; the Moon rises in the east shortly before sunset on the 6th, and sets in the west soon after sunrise the following morning. As the Full Moon closest to the autumn equinox, this will therefore be the Harvest Moon for 2025. Although traditionally associated with September, every few years the Harvest Moon occurs in October instead - the last time was in 2020, and the next will be in 2028. At this time of year the waning Moon continues to rise soon after sunset for several nights following Full so will remain visible in the early evening sky.
Last Quarter is on the evening of Monday October 13th; the half-illuminated Moon rises in the north-east shortly after 10.00 pm BST and shines high in the south at dawn. Throughout the night the Moon lies to the upper left of the bright planet Jupiter and below the stars Castor and Pollux in the constellation of Gemini. The waning crescent Moon will then continue to be visible in the morning sky up until Sunday 19th – on that morning the very narrow Moon will appear low in the east at dawn, to the upper right of Venus.
New Moon falls around midday on Tuesday October 21st, and the young crescent Moon may be spotted very low in the south-south-west after sunset from Sunday 26th onwards.
First Quarter is on the evening of Wednesday October 29th, with the half Moon shining low in the south in the evening twilight.

Mercury is in the evening sky during October, setting very soon after the Sun. Although the little planet reaches its greatest elongation from the Sun on the 29th it will remain hidden in the bright evening twilight throughout the month.

Venus rises around two hours ahead of the Sun at the start of October and shines brightly at magnitude
-3.9 low in the east in the brightening dawn twilight. It sinks noticeably lower as the month progresses, however, as it moves back in towards the Sun.

Mars sets around half-an-hour after the Sun and like Mercury will be lost in the bright twilight sky.

Jupiter rises in the north-east at around 11.30 pm BST at the beginning of the month and is coming up shortly before 9.00 pm GMT by the end of October. At magnitude -2.2 it shines high in the south-east at dawn.

Saturn is low in the south-east as the sky grows dark on October evenings, and sits around 30o high in the south by the late evening. Saturn was at opposition in September, but with its famous rings currently aligned almost edge-on to Earth the planet is presently shining at a rather modest magnitude of 0.7.

Uranus lies in western Taurus about 5o to the lower left of the Pleiades, and at magnitude 5.6 is an easy binocular object.

Neptune lies in southern Pisces, around 4o to the upper left of Saturn. Binoculars will show it as a faint ‘star’ of magnitude 7.8.

Comet C/2025 A6 Lemmon is expected to become a bright binocular object during October, and may even be visible to the naked eye at its brightest towards the end of the month and into early November.

Discovered on January 3rd 2025 by the Mount Lemmon Survey telescope in Arizona, Comet Lemmon will pass just under 56 million miles from the Earth on October 21st. It will then reach perihelion – its closest to the Sun – on November 8th at a distance of 49 million miles.

At the start of October the comet is in the northeast to the lower right of the stars of the Plough; it is best seen in the early hours of the morning when it appears at its highest in the sky. However over the following weeks it travels westwards, brightening and appearing higher in the early evening sky. By the second week of the month it should be easily visible in binoculars as it passes below the Plough, with current predictions suggesting it could reach naked eye visibility for several nights around October 31st when it will appear above the western horizon after sunset.

The chart below shows the position of the comet above the western horizon at two-day intervals between Octobr 8th. to November 7th.

The ‘Summer Triangle’ of Deneb, Vega and Altair is still prominent on October evenings, standing high in the south as the sky grows dark. To the lower left of the Triangle is the small but eye-catching diamond shape of Delphinus, the Dolphin.

The orange star Arcturus is now low in the north-west with the kite-shape of Boötes the Herdsman stretching above. The little semi-circle of Corona Borealis, the Northern Crown, sits to the left of Boötes and beyond that is Hercules. The most distinctive part of this rather faint constellation is the central group of four stars commonly known as the ‘Keystone’.

In the south is the zodiacal group of Capricornus the Sea-Goat. To the left of Capricornus is another rather faint zodiacal constellation, Aquarius the Water Carrier; this autumn the planet Saturn appears as an additional bright ‘star’ in eastern Aquarius.

Below Aquarius and low above the south-eastern horizon is the white star Fomalhaut, the most southerly of the first-magnitude stars visible from Britain. Fomalhaut just clears the horizon for a few hours on autumn evenings.

The Great Square of Pegasus, the winged horse, is high in the south-east. This pattern is traditionally shown upside-down on the sky, with the horse’s neck and head leading off to the lower right of the Square; the star Enif marks Pegasus’ nose. The stars of Andromeda run off from the opposite corner of the Square, towards the bright stars of the hero Perseus. Above them are Cassiopeia and Cepheus, Andromeda’s mythological parents.

Low in the north-east are the first of the winter constellations – the V-shaped head of Taurus the Bull and the little cluster of the Pleiades or Seven Sisters, along with Auriga the Charioteer and its bright star Capella.

Centred on the Pole, or North, Star are the circumpolar stars – those that remain above the horizon all night long, all year round. The most famous of these are probably the seven stars that make up the pattern of the Plough or Big Dipper, two of which point the way to the Pole Star.

The Milky Way runs from the north-east past Capella into Perseus and Cassiopeia. It then passes almost overhead through the Summer Triangle and down into the south-west