The night sky in June 2017

posted 31 May 2017, 09:37 by Pete Collins
by Anne Holt

Sunrise:    1st     04.46      30th      04.44
Sunset:     1st     21.27      30th      21.41

Astronomical darkness:   none

Full Moon      9th   at  14.09
New Moon   24th   at   03.33

The Summer Solstice, when the Sun reaches its northernmost point in the sky, is on 21st at 05.24.  This is also the longest day, at 17hrs 01min 48sec (9hrs and 33 minutes longer than the shortest in December). Earliest sunrise is 04.39 on 17th,  latest sunset is a week later - 21.41 on 24th

Highlights

More light evenings, not much use for astronomers, though during the last week the nights do begin to draw in - by a few seconds each day. 
Saturn is at its best for the year, we still have 3 faint comets around, and there are a couple 'highlights' which can't be seen: daytime meteor showers and a new moon close to perigee - a new Supermoon.  The full moon this month occurs when the Moon is almost at it's furthest from us, known as a Micromoon.
And there's still a chance of seeing some noctilucent clouds, wispy electric blue clouds, low in the west after sunset and in the east before sunrise - if you happen to be in a dark sky area with a clear horizon. There are some bright late evening passes of the International Space Station for the first 4 days of June, then that's it for evening passes until late July.

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 - it's to the right of, and a bit below, the slightly brighter Saturn.

Planets

Mercury:  in Aries, moving into Taurus on 4th, mag -0.3. A morning object for most of June, but appears too close to the sun to be easily seen.  On 1st it rises at 04.08, only just over half an hour before sunrise. It reaches superior conjunction on 21st and moves into Gemini the following day. Still hardly visible as it becomes an evening object, despite having brightened slightly to mag -1.0.  On 30th it sets 45 minutes afer the sun.

Venus:  in Pisces, mag -4.4. Becoming more prominent in the pre dawn sky,  on 1st it rises almost 90 minutes before the sun.  Reaches greatest western elongaton on 3rd, but it's position then improves as the angle of the ecliptic to the horizon is increasing, so the planet is higher in the sky just before sunrise, despite the decrease in it's apparent distance from the sun. It briefly passes through Cetus on 10th, then into Aries, and into Taurus on 29th.  On 30th it rises at 02.27,  2 hours 17 mins before the sun.

Mars: in Taurus.mag 1.7. Appears very close to the sun throughout June, so not visible.  Sets about 90 minutes before sunset on 1st, so not bright enough to be easily seen in the twilight.  By 30th it sets only 33 minutes after sunset.

Jupiter:  in Virgo, mag -2.2. Now past its best for this year but still prominent in the early part of the night.  Reachs its highest point in the sky before sunset, setting at 03.10 on 1st.  In the early hours of 3rd the 74% waxing moon passes close by - separated by only 1.4 degrees at 02.20.  At the start of June it is retrograde but on 10th it goes back to prograde motion (moving eastwards against the background stars).  For an explanation of this see   earthsky.org/space/what-is-retrograde-motion    By month end it sets at 01.10 and will have dimmed to mag -2.0.

Saturn:  in Ophiuchus, mag 0.1. Now at it's best for this year and visible all night, but, unfortunately, still low in the sky - maximum 15 degrees above the southern horizon.  On 10th, at 01.00 it is just 2 degrees south of the full moon.  The rings now appear wide open, at their best since 2003, and, on a couple of nights either side of opposition on 15th, will appear much brighter than usual. This is because the direct sunlight on the individual particles making up the rings means that the shadows are not visible.  This is known as the Seeliger effect.

Uranus:  in Pisces, mag 5.9. A morning object, barely visible in the dawn sky in early June: on 1st it rises only 90 minutes before the sun. On 3rd it is 1.75 degrees from Venus at 03.30 - unfortunately this is only a few minutes after they rise.  By month end it rises at 01.18 and might be visible in binoculars in the early hours.

Neptune:  in Aquarius, mag 7.9. Rises a few minutes after 2am on 1st and soon after midnight on 30th. Should be visible in amateur telescopes as a small blue disc in the later part of the month.  Retrograde motion from 17th.

Meteor Showers

No major showers in June.  The Antihelion source, with a radiant moving through Ophiuchus and Sagittarius, is active early in the month and again towards the end,  ZHR 3-4.

June Bootids,  June 22nd to July 2nd, peak 27th.  ZHR is extremely variable - has been known to occasionally reach 100 but often none at all are seen. This is because the orbit of the parent comet, 7P/Pons - Winnecke has altered and it is now further from that of Earth.  A good display happens when we cross a dust cloud on the previous orbit. This is not predicted to happen this year.

June Lyrids:   Peak  15th/16th. A  ZHR of 8 - 10 has been reported in the past but there has been no activity in recent years.  Parent comet not known but probably another whose orbit has shifted.

There are also a few daytime showers, only detectable using radar or radio telescopes.  They were first seen in 1947 at Jodrell Bank, when a team including Prof (later Sir) Bernard Lovell was studying cosmic rays. The major one of these is the daytime Arieds, active May 22nd to July 7th, peak June 7th,  ZHR up to 30.  The radiant is 30 degrees from the sun and a few meteors have been observed visually around this time, in the pre dawn sky.
We also have the Zeta Perseids, peak 9th, and the Beta Taurids, on 25th.

Comets

The three faint comets are still around. 

V2/Johnson is predicted to remain at peak brightness of around 6.7 during the first week of June, however the waxing gibbous moon will interfere during this time.  Starts the month in Bootes, passing about 5 degrees east of Arcturus on 5th and 6th.  On 15th it crosses into Virgo.

71P/Clark is a telescopic object, mag around 11.8.  On 1st, at 01.00,  it passes 2 degrees east of Antares as it moves southwards.

41P Tuttle-Giacobini- Kresak is still moving southwards between Aquila and Ophiuchus.  By the end of June it will be a little to the north west of the mid point between Altair and Saturn.
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