The night sky in June 2018

posted 31 May 2018, 12:13 by Pete Collins   [ updated 29 Jun 2018, 13:21 ]
by Anne Holt

Sunrise      1st:  04.47        30th:   04.43
Sunset       1st:  21.27        30th:   21.41

Earliest sunrise  17th at 04.39.    Latest sunset 24th at 21.42 
The Summer Solstice, when the Sun reaches its highest point in the sky, is on Thursday 21st at 11.07.  This is also the longest day - 9hrs 33 minutes longer than at the Winter Solstice.

Astronomical darkness:  none

New Moon:  13th at 20.43     Full Moon:  28th at 05.53
June's full Moon is known as the Strawberry Moon, because it's the time when wild strawberries begin to ripen.   Alternative names are the Rose Moon or Mead Moon.
The Moon is at perigee  (closest point in its orbit to Earth) on 15th, and at apogee (furthest point) on 2nd and again on 30th. 

Highlights

We still have far too much light this month.  Not only do we have no astronomical darkness in June, we have very little astronomical twilight, when the sun is between 12 and 18 degrees below the horizon - about 3 hours in early June, falling to 2 for the second half of the month.  Saturn is at opposition on 27th, so at its best for the year, though still very low in the sky.  Mars is brightening rapidly but Jupiter is now beginning to fade, and sets soon after 2am by month end.  And, of course, Venus is still dominating the sky in the west after sunset, setting around midnight throughout the month.  Finally, we are now in the season for noctilucent clouds.  These blue tinged, wispy clouds may be see low in the NE 90 mins to 2 hours before Sunrise, and in the NW a similar time after Sunset.  They are made up of ice crystals about 50 miles up - so high that they catch the light of the Sun while it is below the horizon.

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 -1.7. Not easily seen this month.  On 1st it rises only 19 minutes before the Sun, when the sky is too bright for it to be visible.  It reaches Superior Conjunction, when it is on the far side of its orbit from the Earth, on 5th, after which it becomes an evening object.  It moves into Gemini on 14th but is still not visible, despite having brightened to mag -2.4, as it is only 2 degrees above the Western horizon at dusk. It then moves into Cancer on 28th and on 30th it sets 81 minutes after Sunset, at 23.02.  It will have faded to mag -0.3 and still be too low to be seen:  only 3 degrees above the horizon as the sky begins to darken.

Venus:  in Gemini,  mag -4.0. Still shining very brightly in the late evening Western sky.  On 1st it sets at 00.15 and is 16 degrees above the horizon as the sky darkens around 22.00. On 10th and 11th it will form a line with Castor and Pollux, very low in the NW as the sky begins to darken, with Venus the lowest and about 100 times brighter than the twins.  Try looking a few minutes either side of 23.00, when the sky will be in nautical twilight and the brightest stars can be seen. The trio should be visible from a dark sky site with a low NW horizon - provided that there's no skyglow from nearby towns spoiling the view.  Venus moves into Cancer on 13th, when it will be 15 degrees above the horizon at 22.00, and on 16th the 3 day old Moon passes a little over 2 degrees South of Venus.  They are at their closest at 14.13 but should still be close enough to be in the same binocular field of view, 14 degrees above the horizon, at around 22.15. It moves into Leo on 30th, when it sets at 23.42.  It will be slightly lower in the sky, 12 degrees at 22.10, but slightly brighter at mag -4.1.

Mars: in Capricorn mag -1.2. On 1st it rises at 01.10 and reaches 13 degrees in the South as dawn begins to break.  It brightens rapidly during the month and also appears to be getting larger as it gets closer to us. From 28th it appears to change direction and move Westwards against the background stars.  This is known as retrograde motion and occurs when Earth overtakes an outer planet, in the same way that a moving vehicle may appear to be going backwards to people in a car overtaking it. By 30th it rises at 23.37 and reaches its highest point, 13 degrees in the South, at 03.27.  It will then be at mag -2.1, almost as bright as Jupiter - and much more colourful to the naked eye.  However it is still below the celestial equator, so much better seen from further South.

Jupiter:  in Libra,  mag -2.5. Now past its best for this year.  On 1st it reaches its highest point, 21 degrees above the Southern horizon, at 23.30 and sets at 04.20, just under half an hour before Sunrise.  Like Mars it is now retrograde, but unlike Mars it is now beginning to fade.  On 30th it culminates 20 minutes before Sunset and should be visible 20 degrees above the Southern horizon at around 22.00, before setting at 02.02   By this time it will have faded slightly to mag -2.3.   

Saturn:  in Sagittarius, mag 0.2. On 1st it rises at 23.10 and culminates at 03.03, 14 degrees above the Southern horizon.  Also on this day it will be slightly less than 1 degree South of the 94% lit Moon soon after midnight.  It reaches opposition on 27th, still very low in the sky, only 14 degrees at 01.13 when it is at its highest.  However it is well worth seeing through a scope, especially from a site with a low, clear, unpolluted Southern horizon, as the rings will be a spectacular sight for a few days either side of opposition.  They appear much brighter because of something known as the Seeliger effect: when the Sun shines directly on to the rings the shadows cast by the individual component particles are directly behind them and can't be seen, rather than being seen to the side, thus dimming the rings.  Also they are currently wide open, angled at 26 degrees to the line of sight.  The bad news is that, because Saturn moves so slowly across the sky, the next few oppositions will also be when the planet is very low.  It is improving, though, in 2022 it will be at 20 degrees, almost as high as Jupiter is now.  It then gets better quite quickly and in 2028 will be in Aries, highest point 49 degrees - so be patient. The full Moon passes close to the planet near the end of the month, about 1 degree to the North on the night of 27/28th.  On 30th it culminates at 01.00 and sets at 04.49, a few minutes after Sunrise.

Uranus:  in Pisces, mag 5.9. Very difficult to see this month.  On 1st it rises at 03.18, about 90 minutes before the Sun, but the sky will be too light for it to be seen.  Rises at 01.26 on 30th, 3hrs 17 minutes before Sunrise, as the sky begins to brighten, so won't be visible to the naked eye, even under ideal conditions.  Might be spotted, very low down, with binoculars or a scope from a site with a good Eastern horizon but be very careful - keep an eye on the time and stop well before Sunrise.

Neptune:  in Aquarius,  mag 7.9. On 1st it rises at 02.11 but the sky is beginning to brighten at this time.  On 30th it rises 4hrs 26 minutes before the Sun, while the sky is quite dark - or as dark as it gets at this time of year - but will only reach an altitude of 9 degrees in the South as the sky brightens.   As before, take great care when using scopes before sunrise.

June isn't a very good time for trying to spot, or image, dwarf planets because they are mostly very faint and the sky never gets properly dark.

Haumea, in Bootes at mag 17.4 might be a reasonable imaging target, especially in the early part of the month, when it will be about 50 degrees above the SW horizon around midnight.

Makemake, in Coma Berenices mag 17.0 could possibly be found in early and late June.  On 1st it is 50 degrees above the SW horizon around midnight.  This falls to 27 degrees by 01.00 on 18th, then it becomes very hard to find as the sky is too bright.  Might be visible for a few minutes during the last few days, about 26 degrees in the West, around 1am.

Pluto, Eris and Ceres are all very low and very difficult to find in the less than perfect darkness.

Asteroid Vesta reaches opposition on 19th, in Sagittarius.  At mag 5.3 it is theoretically a naked eye object from a dark sky site but, in practice, is unlikely to be visible as it is very low in the sky - about 15 degrees at its highest.  And, if that wasn't enough, it is currently in an area of the sky where the Milky Way is rather bright.

For more information on the exact positions of planets, dwarf planets etc, see
Dwarf planets are shown under 'asteroids'.
Another useful site is https://theskylive.com


Meteor Showers

No major showers this month, and not much in the way of minor ones either.

June Lyrids, peak 15/16th.  A ZHR of 8 -10 has been reported in the past but there has been no activity in recent years.

June Bootids:  June 22nd to July 2nd, peak 22nd, ZHR variable - has occasionally been as high as 100 but, again, is often zero. The orbit of the parent comet 7P Pons/Winnecke has altered and does not now come as close to Earth as it did in the past. We only get a good display when we pass through a dust cloud on the former orbit.

The antihelion source is active in early and late June though the radiant is very low, in Sagittarius, so they are better seen from further South.

There are several daytime showers in April. These can only be detected using radar or radio telescopes and were first discovered in 1947 by a team including Prof (later Sir) Bernard Lovell, who were studying cosmic rays.   Among these are the daytime Arietids which peak on June 7th, ZHR up to 30.  A few meteors have been observed visually just before dawn around the peak.

Comets

Still nothing brighter than mag 10.   PanSTARRS (2016M1), currently mag 10 and 48P/Johnson, currently mag 13, are said to be brightening - though probably not by much.

Giacobini-Zinner, in Cygnus, reaches perihelion in June.  Now mag 15 but is expected to brighten over the next few months, maybe reaching mag 6.

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