6 days ago
- Science
- Edinburgh Reporter
The astronomical sky above Edinburgh and Lothian in June
June hosts the annual celebration of all things pagan: the Northern Hemisphere
Summer Solstice.
The Solstice, which occurs on 21 June at 3:42 am, marks the Sun's most northerly
altitude and the beginning of astronomical summer which will last for 93 days 15
hours and 37 minutes. If you were to stand on the Tropic of Cancer, the Sun
would be directly overhead at local noon. In Edinburgh and Lothian, the Sun will
reach 57.5 degrees at 1:14 pm. Due to an effect known as the 'precession of the
equinoxes' the Sun is not in Cancer (The Crab) in modern times but Taurus (The
Bull). This, the longest day of the year, will last 17 hours 36 minutes and 24
seconds and you will cast your shortest shadow of the year. Within a few hours of
the Solstice, though, the Sun leaves Taurus (The Bull) and enters Gemini (The
Twins) and recedes from Earth by 397,520 km over the month. Daylight lengthens
from 17:12 (17.206 hours) on 1 June to 17:31 (17.514 hours) on 30 June so we lose
18 minutes of twilit night time by the end of June.
Since the Sun will be at its shallowest point below the northern horizon in
June, and Edinburgh and Lothian sits in the 50–65 degrees band of latitude, we
have an excellent opportunity to observe polar mesospheric clouds, also known as
noctilucent clouds from the Latin for 'night shining'. Noctilucent clouds form
in the mesosphere around 80 km above the Earth. They are visible after sunset and
before sunrise when the observer is still within twilight but the clouds are
sunlit (from below). Typically they are to be found between north-east and
north-west lying below 15 degrees altitude.
The first quarter Moon shows up on 3 June at 4:41 am in Leo (The Lion). Lunar
apogee (furthest from Earth) occurs on 7 June at 11:37 am and takes the Moon to
405,580 km away from Earth—around 21,180 km further than average—subtending
an angle of 29.5 arc-minutes. This is followed by the full Strawberry Moon which
makes an appearance on 11 June at 8:44 am in Ophiuchus (The Serpent Bearer). The
Moon enters last quarter on 18 June at 8:19 pm in Pisces (The Fishes). Lunar
perigee (closest to Earth) occurs on 23 June at 5:38 am and finds the Moon some
363,160 km away from Earth—around 21,240 km closer than average—subtending
an angle of 32.9 arc-minutes. The new Moon appears on 25 June at 11:32 am in
Auriga (The Charioteer) beginning a new synodic month which will last 29 days,
8 hours and 40 minutes.
Regulus in Leo (The Lion) will be 1.8 degrees south of the first quarter Moon on
2 June at 1:30 am. The Pleiades (M45) in Taurus (The Bull) will be 0.6 degrees
south of the waning crescent Moon on 23 June at 2:59 am.
For the inferior planets: Mercury begins the month in Taurus (The Bull) and ends
in Cancer (The Crab) and approaches Earth by 64,772,840 km. Contrarily, Mercury
decreases in brightness from -2.17 to 0.40 magnitudes over the month as it's
sunlit phase reduces until it reaches dichotomy (half-phase) on 28 June. Venus
begins the month in Pisces (The Fishes) and ends in Taurus (The Bull) and recedes
by 35,575,400 km so decreases in brightness from -4.39 to -4.14 magnitudes over
the month. The 'Morning Star Planet' will reach greatest western elongation on 1
June at 4:30 am and dichotomy (half-phase) later the same day. She reaches
aphelion (farthest from the Sun) on 12 June. On 22 June, Venus will appear below
the waning crescent Moon in the pre-dawn eastern sky.
For the superior planets: Mars remains in Leo (The Lion) all month but recedes
by 34,393,273 km. Consequently, the 'Red Planet' fades in brightness from 1.28
to 1.49 magnitudes over June. At midnight on 16/17 June, Mars will be 0.7
degrees north of Regulus in Leo (The Lion). On 29 June at 11:00 pm, Mars will be
within 0.2 degrees of the waxing crescent Moon, low in the western sky. The
following night, it will be fully occulted by the Moon but this event will be
below our horizon. Jupiter begins June in Taurus (The Bull) and ends in Gemini
(The Twins). The 'Gas Giant' recedes by 9,528,863.7 km and diminishes in
brightness from -1.91 to -1.89 magnitudes. Jupiter reaches (solar) conjunction
on 24 June and is lost to us for observing. Earth and Jupiter will be farthest
apart for the year on 26 June.
Saturn remains in Pisces (The Fishes) all month but comes closer by 73,493,246
km. The 'Ringed Planet' increases in brightness from 1.08 to 0.96 magnitudes.
On 19 June at 3:47 am, Saturn will be 3.4 degrees south of the waning crescent
Moon and reaches western quadrature on 22 June. Uranus remains in Taurus (The
Bull) all month but comes closer by 33,228,276 km. Neptune remains in Pisces
(The Fishes) all month and comes closer by 74,218,490 km. The 'Blue Planet'
reaches western quadrature on 23 June.
The Blaze Star, the recurrent nova T CrB in Corona Borealis (The Northern
Crown), should continue to be monitored for it's much-anticipated brightening
as the constellation is highly visible during evening and night hours all
month.
At the time of our sky map, some constellations visible are Draco (The Dragon)
at zenith, Perseus (The Hero) in the north, Cygnus (The Swan) in the east, Leo
(The Lion) in the west, and Serpens Caput (The Snake's Head) in the south. The
ecliptic hosts Sagittarius (The Archer), Ophiuchus (The Serpent Bearer),
Scorpio (The Scorpion), Libra (The Scales), Virgo (The Maiden), Leo (The Lion)
and Cancer (The Crab).
We also see 2 bright star triangles in the June sky: The 'Spring Triangle' of
Arcturus in Bootes (The Herdsman), Denebola in Leo (The Lion) and Spica in
Virgo (The Maiden) in the south and the 'Summer Triangle'—Deneb in Cygnus
(The Swan), Vega in Lyra (The Lyre) and Altair in Aquila (The Eagle)—in the
east. Circumpolar constellations—always above the horizon at the latitude of
Edinburgh and Lothian—include Ursa Minor (The Little Bear), Ursa Major (The
Great Bear), Camelopardalis (The Giraffe) and Cepheus (The King).
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