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Post date: May 29, 2021 7:48:2 PM
by Anne Holt
Sunrise 1st: 04.46 30th: 04.44
Sunset 1st: 21.27 30th: 21.41
Earliest sunrise: 17th at 04.39
Latest sunset: 24th at 21.42
Day length 1st: 16.40.54 30th: 16.56.58
Longest day: 21st: 17.01.52
21st is the Summer Solstice, when the Sun reaches its most northerly point in the sky and is overhead at local noon along the Tropic of Cancer. It is also the first day of astronomical summer, forecasters are predicting a heatwave around this time - fingers crossed they are right, if we have to have such short nights, at least let us have some warm days.
Partial solar eclipse visible from Manchester: 10th between 10.06 and 12.26. Maximum, 25%, at 11.15. See Highlights for more details.
Astronomical darkness: none
Astro twilight 1st: 23.39 to 02.36 30th: 00.05 to 02.19
21st: 00.10 to 02.10
New Moon: 10th at 11.52
Full Moon: 24th at 19.39 (angular diameter 33’ 01”)
Lunar Apogee: 8th at 03.28 (406228 Km, angular diameter 29’ 24”)
Lunar Perigee: 23rd at 10.59 (359959 Km, angular diameter 33’ 10”)
The June Full Moon is most commonly called the Strawberry Moon, as this is the time when the ripening fruit is gathered. This name was also used by the Algonquin and Ojibwa tribes of N America. Other names given in the Old Farmers Almanac are the Birth Moon, the Blooming Moon, the Egg Laying Moon, the Hatching Moon, the Hot Moon and the Hoer Moon - this one because now is the time when newly sprouting plants need lots of attention.
Celtic names are the Horses Moon and the Mead Moon, it’s the Chinese Lotus Moon, the Neo Pagan’s Planting Moon, the Medieval English Dyan Moon and the Inuit’s Hunting Moon. It was the Colonial American Rose Moon and among the many names used by Indigenous American people were the Cherokee Green Moon, the Choctaw Windy Moon and the Dakota Sioux Moon When the June Berries are Ripe.
Highlights
Astronomers are currently suffering from an excess of light - no astronomical darkness throughout June, and not even a great deal of astro twilight. It begins around midnight and only lasts 3 hours at the start of the month, down to 2 hours around the time of the solstice on 21st.
The upside to this is that there is a chance of seeing some noctilucent clouds, when the Sun is between 6 and 16 degrees below the horizon, 60 to 90 minutes after sunset and before sunrise. As the sky is not completely dark, these wispy silver or blue coloured clouds are best seen away from light polluted towns and cities. The most likely time for spotting some is said to be in the morning nautical twilight, ideally when the Sun is 10 degrees below the horizon.
Jupiter is now higher in the morning sky, reaching 24 degrees by dawn at month end, Saturn is much fainter and a little lower but should also be visible. Venus is an evening object, very low, but very bright, in the twilight sky.
And, if anyone does have radio or radar equipment, June is the best time for daytime meteor showers.
The real highlight this month is the annular solar eclipse on 10th, visible from parts of E Canada, Greenland, Siberia and the North Pole. Because the Moon will be close to apogee at this time, it will appear smaller than average, not big enough to completely cover the Sun’s disc, so a thin ring - known as the Ring of Fire - remains visible round the Moon.
Because it is so far north, the path of annularity crosses many inaccessible, sparsely populated areas with only a 50% chance of cloud free sky. Add to that the current restrictions on travel and it is estimated that no more than 20,000 people will actually witness it.
In the UK we will (weather permitting) see a partial eclipse. From Manchester the Sun will be 25% obscured at the maximum, from London only 20%. Observers up in the Shetland Isles fare better, from there the Moon will cover nearly 40% of the Sun.
Warning: Do not look directly at the Sun, even when it is partly eclipsed. Special eclipse glasses, which cut out most of the light, are available and will enable you to see it safely.
Sunglasses are not dark enough, your eyes could still be damaged.
Constellations
The Plough asterism in Ursa Major is still prominent, being overhead for much of the night, leaving Cassiopeia on the opposite side of the Pole Star, low in the northern sky. The Summer Triangle, consisting of Vega, Deneb and Altair, is now getting higher in the late evening, though Altair, in Aquila, is still quite low in the early part of the night. The beautiful double star Albireo, at the head of Cygnus the swan, is very well placed for observing. The Milky Way is now visible from dark sky sites, running across the sky through the Summer Triangle, passing almost overhead in the early hours. The bright orange red Arcturus is shining brightly high in the SW and, if you manage to find some dark skies not obscured by cloud, you should be able to see the rest of the kite shaped Bootes, with the semicircle of stars forming Corona Borealis just to the east of it. Another red giant, Antares in Scorpio is now visible low on the southern horizon.
Planets
Mercury: in Taurus, mag 3.0
Very difficult to see this month as it appears so close to the Sun. On 1st they both set around the same time and appear separated by 13 degrees. Mercury is at aphelion on 10th, 0.47AU from the Sun, separated by only 3 degrees and down to mag 6.1. The following day it reaches inferior conjunction, passing south of the Sun. On 30th, now at mag 1.0, it is still below the horizon as the sky brightens, rising at 03.47, about an hour before sunrise.
Venus: in Taurus, mag -3.9
An evening object but very low in the sky after sunset. Despite its low altitude, because it is so bright, it should be visible to observers with a low, clear NW horizon. On 1st it is at 5 degrees as the sky darkens, setting at 00.53. It moves into Gemini on 3rd and on 12th at 06.30 the very thin crescent Moon is only 42’ from the planet. The pair are separated by 5 degrees after sunset on 11th but the Moon is lower than Venus and only 1% lit so is unlikely to be visible. On 12th the Moon, now at 4%, is higher and to the left, separated by about 6 degrees. Venus sets at 23.10, the Moon at 23.50. It is at perihelion on this day, at a distance of 0.72AU. It moves into Cancer on 26th, still only 6 degrees at dusk, and is no higher on 30th when it sets at 23.10.
Mars: in Gemini, mag 1.7
Now low in the WNW at dusk. On 1st it is only 10 degrees as the sky darkens, setting at 00.35. It moves into Cancer on 9th, when it is only 6 degrees in the twilight. On 13th the 13% Moon passes 2 degrees 48’ directly north at 20.52. They are slightly closer, 2 degrees 46’, at 22.11 in civil twilight, when Mars will be 14 degrees above the horizon but too faint to be seen in the still bright sky. It will be down to 5 degrees when the sky darkens, setting at 00.06. From 22nd to 24th it passes through the Beehive Cluster very low in the WNW soon after sunset. On 30th, now at mag 1.8, it is on the horizon at dusk, setting at 23.21.
Jupiter: in Aquarius, mag - 2.5
Now becoming very prominent in the morning sky. On 1st the 54% Moon passes 4 degrees 21’ to the south at 12.56. The pair should be visible, separated by 7 degrees, at 03.00, down to 7 degrees by dawn when the planet will have reached 17 degrees. It begins retrograde motion (appearing to move from east to west) on 20th, when it rises soon after midnight and reaches 22 degrees in the SE by dawn. On 28th it is again close to the Moon, which is now at 76% and passes 4 degrees 27’ to the south at 19.41, on the morning of 29th they are separated by 5 degrees. On 30th Jupiter rises at 23.56, becomes visible around 1am and reaches 24 degrees in the SE by dawn.
Saturn: in Capricorn, mag 0.6
Slightly lower and much fainter than Jupiter but should be visible in the morning sky. On 1st it rises at 02.12, high enough to be seen by 3am and reaching 15 degrees in the SE as the sky brightens a little before 4am. On 27th the 87% Moon passes 4 degrees 01’ to the south at 10.26. On this day the planet should be visible from 01.00, when the Moon is 8 degrees to the SW, until dawn breaks at around 4am, with Saturn at 18 degrees in the SW. On 30th it rises at 23.14 and is high from 01.00, and visible until the sky gets too light at around 03.45. The planet’s north pole is currently tilted towards us by 18.3 degrees, so the rings show well when viewed through a scope.
Uranus: in Aries, mag 5.9
Not visible this month. On 1st it is still 11 degrees below the horizon as the sky begins to brighten, rising at 03.38, just over an hour before the Sun. On 30th it rises at 01.46 in astro twilight but is still very low when dawn breaks.
Neptune: in Aquarius, mag 7.9
On 1st it is still just below the horizon at dawn, rising at 02.21. It begins retrograde motion on 25th, when it reaches 5 degrees in a fairly dark sky. On 30th it rises at 00.30 and only gets to 10 degrees before the sky brightens.
Dwarf Planets
Ceres: in Cetus, mag 9.3
The closest of the dwarf planets, and the only one which is really accessible to the average amateur astronomer, is not visible this month as it is still below the horizon at dawn.
Pluto: in Sagittarius, mag 15
Still too low for imaging, despite rising at 00.38 on 1st and 22.43 on 30th. It is currently quite far south and, because it takes so long to orbit the Sun, it moves very slowly around the sky and, for Manchester observers, won’t get up to 20 degrees for another 40 years.
Haumea: in Bootes, mag 17.4
Best placed for imaging in early June. On 1st it is at 50 degrees in the west as the sky darkens around midnight, remaining high throughout astro twilight. By 30th it is only at 32 degrees as the sky fades before 1am, down to 23 degrees by dawn.
Makemake: in Coma Berenices, mag 17.2
On 1st it is at 49 degrees in the SW as the sky fades around midnight, remaining reasonably high until dawn. On 30th it is at 27 degrees in the west at 00.40 and only high enough for imaging for about half an hour.
Eris: in Cetus, mag 18.8
Still below the horizon at dawn throughout June.
Asteroids
3 Juno: in Ophiuchus, mag 10.1
Reaches opposition on 6th, when it rises at 19.42 and culminates, 32 degrees in the south, at 01.22. High enough for imaging from 00.17 until dawn.
30 Urania: also in Ophiuchus, mag 11.1
Opposition on 14th. Much lower than Juno, despite being in the same constellation. Culminates at 01.17 but only reaches 10 degrees in the south.
Comets
Still nothing spectacular - or even fairly reasonable.
18P/Finlay is at perihelion on 18th, predicted mag 8.7, but is below the horizon during the hours of darkness for UK observers.
C/2020 T2 (Palomar) in Bootes, mag 10.1
Fainter but better positioned. On 1st it is high in the sky from midnight, reaching 52 degrees in the SW before the sky brightens. By the end of June it is only high for a very short time, 23 degrees in the west from 00.40 to 00.54.
Meteor Showers
Nothing spectacular this month, we have a few showers which may (or may not) provide a few meteors.
June Bootids: active June 22nd to July 2nd, peak June 27th.
ZHR given as variable - could be anything from zero to 30, very occasionally more - in 1998 a peak of around 100 was observed. Peak activity predicted for 11am on 27th. The radiant is circumpolar, highest at 22.00 so the shower is best seen after midnight when the sky is reasonably dark. They are very slow moving, long lasting meteors, parent comet 7P/Pons-Winnecke. The gibbous Moon will interfere, rising just before midnight on 27th.
June Lyrids: active 10th to 21st, peak 15th/16th ZHR 8.
This shower was first detected in 1966 and was active for a few years but hasn’t shown much activity recently. They were medium paced, mainly faint, blue coloured meteors with a few brighter ones which left trails. This shower isn’t mentioned in this year’s IMO calendar.
Beta Taurids: active June 5th to July 18th, peak June 28th, ZHR weak.
Again, not in the IMO calendar. This shower is notable only because the 1908 Tunguska meteor is thought to be associated with it.
Antihelion Source (ANT) active in early and late June, however the radiant, in Sagittarius, is very low. ZHR 2 to 4.
There is still some daytime activity - meteors detectable with radio or radar equipment.
Daytime Arietids: active May 14th to June 24th, peak June 7th, ZHR 30
The radiant of these is only 30 degrees west of the Sun, however a few meteors might be spotted visually in the morning twilight of 7th. Better seen from further south, where the sky is a little darker.
Zeta Perseids: active May 20th to July 5th, peak 9th or 13th (?)
This shower was first detected in 1947 by radio astronomers working at Jodrell Bank. Parent comet 2P/Encke
Credits
Most of the solar system information given here is from:
More information, exact co-ordinates and finder charts of all solar system objects can be found on this site.
Also quite useful is https://theskylive.com
https://www.imo.net/resources/calendar/
https://www.timeanddate.com
Other information is from various internet sources, including NASA, Britannica, Space Facts, Universe Today and, when all else fails,Wikipedia.
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