June brings our summer solstice on the 21st and sees Jupiter remain as the stand-out object in a night sky that is blighted by persistent twilight at our latitudes. The latter is so severe over northern Britain that it swamps all but the brighter stars and planets. Those bright stars include Vega in Lyra which is high in the E by our map times as the Summer Triangle it forms with Altair in Aquila and Deneb in Cygnus returns to prominence.
The Sun follows a shallow arc below our N horizon overnight, the geometry allowing views of noctilucent clouds, or NLCs, whose silvery-blue tracery may gleam low down between the NW after nightfall and NE before dawn. NLCs, formed by ice crystals coalescing around dust particles, float near 82km in altitude where they reflect sunlight after our normal clouds are in darkness.
Jupiter is now unmistakable in the SSW at nightfall but shifts rather lower into the WSW by our map times and sets in the W two hours later. As it dims a shade between mag -2.2 and -2.0, its slow westerly progress against the stars of Virgo reverses at a stationary point on the 10th when it lies 3° SE of the double star Porrima. Shrinking in width from 41 to 37 arcsec, it stands near the Moon on the 3rd and 30th.
Saturn lies below the full Moon on the 9th/10th and comes to opposition on the 15th when it is directly opposite the Sun at a distance of 1,353m km. Prominent at mag 0.0 in Ophiuchus, it stands 16° left of Antares in Scorpius but only 10° to 15° high in the S at our map times. Its disc spans 18 arcsec, with bands of cloud that are a pale imitation of those of Jupiter. The unrivalled rings, though, stretch for 41 arcsec and are wide open with their N face tipped 27° towards us.
The night ends with Venus blazing in our E morning twilight as it reaches its furthest W of the Sun on the 3rd and dims only slightly from mag -4.3 to -4.1 during June. Its altitude almost due E at sunrise improves from 8° to 18° this month and by the end of the period it rises more than two hours before the Sun. Look for it to the left of the waning Moon on the 20th when a telescope shows it to be 20 arcsec wide and 58% illuminated. Both Mercury and Mars stay hidden in the Sun’s glare.
June diary
1st 14h First quarter
3rd 13h Venus furthest W of Sun (46°)
4th 01h Moon 2.3° N of Jupiter
9th 14h Full moon
10th 02h Moon 3° N of Saturn; 06h Jupiter stationary
15th 11h Saturn at opposition
17th 13h Last quarter
20th 22h Moon 2.4° S of Venus
21st 05:25 Summer solstice; 15h Mercury in superior conjunction
24th 04h New moon
28th 02h Moon 0.03° S of Regulus
Times are BST
