Saturn, Mars and Jupiter end Scotland’s planetary drought

Alan Pickup

Author: Alan Pickup

The maps show the sky at 01:00 BST on the 1st, midnight on the 16th and 23:00 on the 31st.

Planet-watchers at our latitudes have had little to excite them of late. While observers in the southern hemisphere could watch Saturn and Mars climbing high in their eastern morning sky, those planets struggled to emerge from the twilight that dogs our summer nights.

C41 Mel 25 Hyades Open Cluster Taurus mag. 0.5 (Fran Goodman)

Hyades and Pleiades open clusters in Taurus, Fran Goodman

Things are looking up, though. Not only is the twilight beginning to abate after the Sun turned southwards at the solstice but I can confirm that Scotland’s planetary drought is at an end. We still need to rise very early (or stay up very late) if we wish to see many of them, but those of us who do are rewarded by the sight of Mars as it speeds towards the conspicuous giant planet Jupiter. The convergence occurs in Taurus, with the star Aldebaran and the iconic Pleiades and Hyades star clusters in close attendance.

The Sun sinks 5° southwards during July as Edinburgh’s sunrise/sunset times change from 04:32/22:01 BST on the 1st to 05:16/21:21 on the 31st.

L2 Earthshine Ramsay McIver Canon EOS Ra

Waxing Moon Earthshine, Ramsay McIver

The Moon is a waning crescent in the eastern sky before dawn on the 1st as it stands 8° above and right of Mars which shines at magnitude 1.0 in the constellation Aries. On the 2nd, it lies to Mars’ left and between Mars and the Pleiades. Earthshine becomes more pronounced as the Moon tracks eastwards to lie below-left of the Pleiades and 4° above Jupiter on the 3rd.

New moon comes at midnight BST on the 5th/6th and we might be able to glimpse the very young Moon at nightfall on the 7th when it is the thinnest of slivers, only 4% illuminated and 5° high in the west-north-west forty minutes after sunset. Binoculars may help to show it, and (with luck) also reveal Mercury just 2.2° below it and shining at magnitude -0.1. Mercury may be hard to see again is it moves to 27° east of the Sun in our evening twilight on the 22nd. Venus, even closer to the Sun in the twilight, is also unlikely to be visible, despite its brilliance at magnitude -3.9.

Picking up the Moon’s monthly journey, earthshine is prominent again on the 9th when it stands 4° above-left of Regulus as Leo dives headlong into the west at nightfall. The Moon is at first quarter when it lies to the right of Spica in Virgo low in the south-west on the 14th and it stands just below-left of Antares in Scorpius on the 17th. Full moon occurs on the 21st as it moves from Sagittarius into Capricornus while on the 24th it lies just left of Saturn. The latter rises in the east about thirty minutes before our map times and climbs to stand some 25° in the south-south-east before dawn. Telescopes show it to be 18 arcseconds wide at mid-month, with the rings 42 arcseconds wide but less than 2 arcseconds thick, their north face being tipped at a mere 2° to our view.

After reaching its last quarter in Aries on the 28th, the Moon lies 2° below-left of the Pleiades before dawn on the 30th. It is also 5° above Mars which, in turn, hovers above the V-formation Hyades cluster and Aldebaran.

Noctilucent Clouds taken from Edinburgh, John Briggs

The 31st finds the Moon’s 20% crescent 10° to the left of Mars and 5° above-left of Jupiter, making for an impressive sight as they rise in the north-east during the hour after midnight, and climb to stand around 30° high in the east as the dawn twilight floods the sky. By then, Mars appears as a tiny 6 arcsecond ochre disk through a telescope, dwarfed by the 35 arcseconds of Jupiter. The two sit 9° apart as the month ends and are destined for a close conjunction on 14 August when Mars passes less than a Moon’s breadth above Jupiter.

Our charts show the Plough in the middle of our north-west and Capella in Auriga near its low point in the north. Remember to remain alert for the high-altitude noctilucent clouds I mentioned last time – typically, we see these hanging low down in the northern quarter of the sky, appearing bluish and cirrus-like as they catch the Sun’s light long after our usual clouds are in darkness.

M20 Trifid Nebula, Mark Phillips, ASERO/Murrell telescope

On the opposite side of our sky, low in the south, are the star-rich constellations of Scorpius and Sagittarius and the direction towards the centre of our Milky Way galaxy. There is also a surfeit of nebulae and star clusters, most of them poorly placed for us northern observers given our summer twilight and their low altitude.

The Summer Triangle, formed by Vega in Lyra, Altair in Aquila and Deneb in Cygnus, begins to transit our high meridian at the map times and also carries a wealth of interesting objects. One of the quirkiest is the Coathanger located a third of the way from Altair to Vega. Binoculars show a pattern of stars that resemble an upsides-down coat hanger – a line of stars about three Moon’s breadths long and a “hook” below them. Once thought to be a real star cluster, and called Brocchi’s cluster, we now realise it comprises a chance alignment of stars that lie hundreds of light years apart.

Coathanger using the ASERO/Dalrada telescope, inverted so the “hook” is at the top

To the east of the Triangle is the small and pretty constellation of Delphinus the Dolphin – the ancient Greeks imagined its five brighter stars forming a dolphin’s body and tail. The star called G on our chart is Gamma Delphini which is a glorious double star through a telescope. Its two stars, appearing 9 arcseconds apart with contrasting yellow and blue-green hues, lie 115 light years from us and orbit each other every 3,249 years.

Astronomers puzzled for years about the origins of the names, Sualocin and Rotanev, for the two brighter stars Alpha and Beta, labelled as A and B on our chart. Then the penny dropped that, read backwards, these read Nicolaus Venator which is Latin for the name of the 19th century astronomer who first listed them!

Diary for 2024 July

Times are BST

  • 1st 19h Moon 4° N of Mars
  • 2nd 11h Moon 4° N of Uranus
  • 2nd 17h Moon 0.3° S of Pleiades star cluster
  • 3rd 09h Moon 5° N of Jupiter
  • 5th 06h Earth at aphelion, furthest to Sun (152,099,968 km)
  • 6th 00h New Moon
  • 7th 04h Mercury 0.2° N of Praesepe star cluster
  • 7th 20h Moon 3° N of Mercury
  • 13th 08h Jupiter 5° N of Aldebaran
  • 14th 00h First quarter
  • 14th 03h Moon 0.6° N of Spica
  • 15th 10h Mars 0.6° S of Uranus
  • 17th 21h Moon 0.2° N of Antares
  • 21st 11h Full Moon
  • 22nd 08h Mercury furthest E of Sun (27°)
  • 24th 22h Moon 0.4° N of Saturn
  • 28th 04h Last quarter
  • 29th 18h Moon 4° N of Uranus
  • 29th 23h Moon 0.1° S of Pleiades star cluster
  • 30th 12h Moon 5° N of Mars
  • 31st 01h Moon 5° N of Jupiter

This is an extended version, with added diary, of Alan’s article published in The Scotsman on 29 June 2024, with thanks to the newspaper for permission to republish here.