May graces us with a new comet, a New Supermoon, a Full Micromoon and the Eta Aquarids meteor shower seeded by Halley’s comet.
After 5 May, the sky never darkens beyond nautical twilight all month long.
The Sun leaves Aries (The Ram) on 13 May at 11:52 pm and enters Taurus (The
Bull) and recedes from Earth by 966,174 km over the month. Daylight lengthens
from 15:24 (15.395 hours) on 1 May to 17:10 (17.165 hours) on 31 May so we lose
1 hour and 46 minutes of night time by the end of May. After 5 May, we never
attain astronomical twilight or darker as the Sun is always above the -18
degrees boundary (so never dips below it).
The first quarter Moon shows up on 4 May at 2:52 pm in Cancer (The Crab). Lunar
apogee (furthest from Earth) occurs on 11 May at 1:34 am and takes the Moon to
406,256 km away from Earth—around 21,856 km further than average—subtending
an angle of 29.4 arc-minutes. This is followed by the full Flower Moon which
makes an appearance on 12 May at 5:56 pm in Libra (The Scales). It is also a
‘Full Micromoon’. The Moon enters last quarter on 20 May at 12:59 pm in
Aquarius (The Water Bearer). Lunar perigee (closest to Earth) occurs on 26 May
at 2:28 am and finds the Moon some 359,013 km away from Earth—around 25,387
km closer than average—subtending an angle of 33.3 arc-minutes. The new Moon
appears on 27 May at 4:02 am in Taurus (The Bull) beginning a new synodic month
which will last 29 days, 7 hours and 29 minutes. The new Moon is also a ‘New
Supermoon’.
Pollux in Gemini (The Twins) will be 2.1 degrees north of the waxing crescent
Moon in the early hours of 3 May. Antares in Scorpio (The Scorpion) will be
0.3 degrees north of the waning gibbous Moon before sunrise on 14 May.
For the inferior planets: Mercury begins the month in Pisces (The Fishes) and
ends in Taurus (The Bull) and recedes by 48,648,853 km. Contrarily, the ‘Swift
Planet’ increases in brightness from 0.15 to -2.17 magnitudes over the month.
Mercury is lost behind the Sun on 29 May when it is furthest from Earth and
reaches superior conjunction the following day. He is closest to the Sun on the
last day of the month. Venus remains in Pisces (The Fishes) all month but
recedes by 36,100,539 km. Venus decreases in brightness from -4.72 to -4.39
magnitudes over the month but is still with us as the glorious ‘Morning Star
Planet’.
For the superior planets: Mars begins the month in Cancer (The Crab) and ends
in Leo (The Lion) but recedes by 40,892,375 km. The ‘Red Planet’ decreases in
brightness from 0.94 to 1.28 magnitudes over the month. Planet spotters will
have little difficulty in seeing Mars but, if you need a hint, on 3 May the
Roman god of war will be 2.1 degrees south of the waxing crescent Moon in Cancer
(The Crab). Jupiter remains in Taurus (The Bull) all month and recedes by
36,842,985 km. The ‘Gas Giant’ fades in brightness from -1.98 to -1.91
magnitudes over May.
Saturn remains in Pisces (The Fishes) all month but comes closer by 63,816,018
km and, so, increases in brightness from 1.17 to 1.08 magnitudes. Uranus
remains in Taurus (The Bull) all month and recedes by 2,005,930 km. The ‘Ice
Giant’ reaches Solar conjunction on 17 May and is lost to us. Uranus is
furthest from the Earth, all year, on 18 May. Neptune remains in Pisces (The
Fishes) all month but comes closer by 62,526,245 km.
There are 2 meteor showers in the May sky for Edinburgh and Lothian. The strong
Eta Aquarids (031 ETA), radiant from Aquarius (The Water Bearer), began last
month and are active until 28 May. They peak on 6 May with up to 50 meteors per
hour. The radiant rises around 3 am on 6 May so the shower, with a ZHR=50, will
be visible for 90 minutes—the waxing gibbous Moon illuminated to 71%
notwithstanding—before sunrise spoils the show. These are one of only 2
meteor showers seeded by the world’s most famous comet: 1P/Halley. The very
weak Eta Lyrids (145 ELY), radiant from Lyra (The Lyre), are active between
3–14 May and peak on 10 May with barely 3 meteors per hour. This shower is
associated with comet C/1983 H1 IRAS-Araki-Alcock. They are very hard to see
and the almost full Moon won’t help. They will be radiant from an area between
Vega and Deneb: two of the bright stars in the ‘Summer Triangle’.
A new comet was discovered, serendipitously, last month by the NASA’s Solar and
Heliospheric Observatory (SOHO) satellite. Since the instrument used in the
discovery was SWAN, it was dubbed SWAN25F but it’s correct designation is now
C/2025 F2 (SWAN). SWAN—or to give it it’s full name the Solar Wind
Anisotropies instrument—maps hydrogen, specifically Lyman-alpha radiation, in
the solar wind and the sudden brightening may be attributed to an outburst at
these wavelengths. It may be visible to the naked eye, but certainly visible
with a telescope or binoculars, after sunset during the first week of the month
near the Pleiades (M45) in Taurus (The Bull) but will fade quickly.
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 Ursa Major (The
Greater Bear) at zenith, Cepheus (The King) in the north, Hercules (Hercules)
in the east, Gemini (The Twins) in the west, and Corvus (The Crow) in the
south. The ecliptic hosts Libra (The Scales), Virgo (The Maiden), Leo (The
Lion), Cancer (the Crab), Gemini (The Twins) and Taurus (The Bull).
If you wish to have a late night, around midnight mid-month, try seeking out
some prominent Messier objects visible on our sky map. These will need a
telescope or binoculars but M82 (Cigar Galaxy), M101 (Pinwheel Galaxy) and M51
(Whirlpool Galaxy) will all be close to zenith and M87 (Virgo A), in the south,
will be at a reasonable airmass. M44 (Beehive Cluster also known as Praesepe)
and M67 (Golden Eye Cluster) will be in the west, near Mars.
We also see 3 bright star triangles in the May sky. The ‘Spring Triangle’ of
Arcturus in Bootes (The Herdsman), Denebola in Leo (The Lion) and Spica in
Virgo (The Maiden) is south-east. The ‘Winter Triangle’—Procyon in Canis
Minor (The Lesser Dog), Sirius in Canis Major (The Greater Dog) and Betelgeuse
in Orion (The Hunter)—sets early in the west and after midnight the ‘Summer
Triangle’—Deneb in Cygnus (The Swan), Vega in Lyra (The Lyre) and Altair in
Aquila (The Eagle)—rises in the east. Circumpolar constellations—always
above the horizon at the latitude of Edinburgh and Lothian—include Draco (The
Dragon), Perseus (The Hero), Cassiopeia (The Seated Queen) and Camelopardalis
(The Giraffe).
Founding Editor of The Edinburgh Reporter.
Edinburgh-born multimedia journalist and iPhoneographer.
