The night sky in May 2019

posted 29 Apr 2019, 12:44 by Pete Collins   [ updated 29 Apr 2019, 13:33 ]
by Anne Holt

Sunrise      1st:  05.35        31st:  04.48
Sunset       1st:  20.38        31st:  21.25

Astronomical darkness   1st:  23.25  to  02.46     31st:  none

New Moon:  4th at 23.54       Full Moon:  18th at 22.11

Lunar perigee:  13th at 21.54  (369015km)
Lunar apogee:  26th at 13.28  (404133km)

This full Moon is a Blue Moon, if we use the original definition of the third full Moon in a season having 4.  The other definition, the second full Moon in a calendar month,  was actually an error in a 1946 article in Sky and Telescope magazine. The wrong definition is now more widely used - probably because it's so much more obvious.
May full Moon is known as the Flower Moon, because of all the blossoms around at this time.  Other names are the Corn Planting Moon and the Old English/Anglo Saxon Milk Moon.

Highlights

Still struggling to find any, unfortunately we have more light than highs - just 3 hrs 21 minutes of astro darkness on the night of the 1st, diminishing rapidly until mid month then we have none at all until the end of July.  The only reasonable meteor shower has a radiant so low that it favours observers in the southern hemisphere and all the planets are either very low in the sky or appear close to the Sun.  And, even though April is known for its showers, in Manchester, May averages slightly more rainfall.

Constellations

As the sky darkens at the start of the month Lyra and Cygnus are rising in the north east, followed a couple of hours later by Aquila.  In the later part of the night the Summer Triangle formed by Vega, Deneb and Altair, the brightest star in each of these three constellations, should be easily visible. By the end of the month Aquila will be above the horizon by around 11pm. The brightest part of the Milky Way visible to us in the UK runs through the Summer Triangle and down through Scutum and Sagittarius.

The Plough is still very high in the sky for most of the night, standing on its handle, so Cassiopeia, the W shaped 'Lady in the Chair',  on the opposite side of the Pole Star is very low down in the north.

Bootes, the herdsman, is now riding high although only Arcturus, the brightest star in the celestial northern hemisphere, is above magnitude 2, so its kite asterism may not be easily visible in our light polluted skies. Arcturus is easy to find though - just follow the arc of the Plough's handle down to the south until you come to Arcturus.  Carry on the arc a bit further and you come to the star Spica, the brightest star in Virgo.

At this time of year when you look up to the south you are looking out of the plane of our Milky Way galaxy instead of along it like you do in winter and summer, so there aren't many bright stars, open star clusters and nebulae. However, if you've got a telescope this is a good time of year to hunt down globular clusters like M13, the Great Globular Cluster in Hercules, and faint galaxies like the many galaxies lying in the bowl of Virgo and into Coma Berenices.

Planets

Mercury:  in Pisces,  mag -0.4.
Not easy to see this month.  On 1st it rises only 20 minutes before the Sun and is still 3 degrees below the horizon as the sky brightens.  It is only 7.5 degrees to the east of Venus but, unlike Venus, Mercury is too faint to spot in the dawn sky.  It moves into Aries on 9th, when it will have brightened to mag -0.8, and Taurus on 19th when it is at mag -2.0 but not visible as its apparent separation from the Sun is only 3 degrees.  It reaches superior conjunction on 21st then becomes an evening object.  On the 31st it is at mag -1.2 and sets at 22.31, over an hour after Sunset but only 4 degrees above the horizon as the sky begins to darken.

Venus:  in Pisces, mag -3.9.
Still a morning object but very low.  On 1st it rises at 04.58, only 37 minutes before the Sun and is on the horizon as the sky brightens.  It might be visible from a site with a very flat, unobstructed eastern horizon.  On 2nd the 6% Moon passes just over 3.5 degrees south of the planet in daylight at 12.41. They remain quite close for much of the day and might be visible to the naked eye - if you know where to look.
As always DO NOT try using binoculars or a telescope to find them, they appear much too close to the Sun for this to be done without risking permanent blindness.
It moves into Aries on 17th and on 31st rises at 04.04, still below the horizon as the sky begins to brighten.

Mars:  in Taurus, mag 1.6.
On 1st it is 19 degrees above the western horizon as the sky darkens around 21.45, setting at 00.26.   On 7th it appears almost midway between the 2 stars marking the horns of the bull and, on the following night, the 9% Moon passes south of the planet, closest at 01.21 when they are separated by less than 4 degrees.  It moves into Gemini on 16th, when it will have faded slighty to mag 1.7.  After several months of setting at around the same time, because its eastern motion counteracted the apparent movement of the celestial sphere westwards, it is now setting earlier - 00.13 on this night - and is much lower in the sky as it gets dark, only 12 degrees in the west. On 31st it is even lower and fainter - mag 1.8 and 6 degrees above the horizon at dusk, setting at 23.51. 

Jupiter:  in Ophiuchus, mag -2.5.
Still a morning object, very bright but very low.  Rises soon after midnight on 1st, reaching 7 degrees in the SE by 02.00 and 13 degrees in the south by 04.05.  On 20th the 94% Moon is just under 4 degrees east of the planet in the early hours.  By 31st it rises at 22.03, is at 7 degrees in the SE by 23.30 and culminates at 01.55, still only 13 degrees above the southern horizon.  It will then be at mag -2.6.

Saturn:  in Sagittarius, mag 0.5.
Another low morning object.  Rises on 1st at 02.05 and only gets to 12 degrees in the south as the sky brightens.  On the night of 22nd/23rd the 82% Moon passes the planet. They are closest while they are still below the horizon but should be visible in the pre-dawn sky, when they are separated by about 2 degrees.  On 31st it rises a few minutes after midnight and reaches 14 degrees in the south by dawn.

Uranus:  in Aries, mag 5.9.
Not visible this month. On 1st it rises only 10 minutes before the Sun and appears separated from it by 7 degrees.  By 31st it rises over an hour before Sunrise but is still well below the horizon when the sky begins to brighten.

Neptune:  in Aquarius, mag 7.9.
Its position is improving slightly but not yet enough to make it observable.  On 1st it rises at 04.17 but is 5 degrees below the horizon as dawn breaks. By 31st it rises at 02.19 but still doesn't quite clear the horizon before the sky brightens.

Dwarf Planets

Ceres: in Ophiuchus, mag 7.6.
The nearest and brightest of the dwarf planets is the only one which orbits in the Asteroid Belt, rather than the much more distant Kuiper Belt.  However it is very low throughout May but might possibly be visible through a small scope from a site with a low southern horizon.  On 1st it rises at 22.53 and culminates, 19 degrees in the south, at 03.21.  It reaches opposition on the morning of 29th when it culminates at 01.08, slightly lower at 18 degrees but brighter at mag 7.0.  It moves into Scorpio on 30th and ends the month rising at 20.33 and culminating at 00.58, still no higher than 18 degrees.

The other dwarf planets are much too faint and too distant to be anything other than photographic targets - and that only for very experienced  astrophotographers.

Pluto: in Sagittarius, mag 14.7.
Still too low to be successfully imaged, reaching a maximum altitude of 14 degrees in the south.

Eris: in Cetus, mag 18.8.
The cause of Pluto's demotion (sorry, that should say reclassification), appropriately named after the goddess of discord, is below the horizon during the hours of darkness this month.

Haumea:  in Bootes, mag 17.3.
On 1st it is at an altitude of 43 degrees in the SE as the sky darkens, culminating at 00.50.  By 31st it should be visible a few minutes before midnight, at an altitude of 51 degrees in the SW,  and remains well positioned for a couple of hours after midnight.

Makemake:  in Coma Berenices, mag 17.1.
On 1st it should be a good photographic target from about 22.15 when it is 43 degrees above the SE horizon, reaching its highest point just over an hour later. On 31st it culminates soon after sunset, and is at 53 degrees in the south west around midnight.

A few small asteroids reach opposition in May, all in Libra.  They are all between mag 9 and 10 so should be visible in amateur scopes.

11th;   8 Flora,  mag 9.7, reaches 26 degrees in the south at 01.19

14th:  11 Parthenope,  mag 9.5, reaches 25 degrees at 01.15

20th;  20 Massalia, mag 9.7, reaches 17 degrees at 00.46

For exact positions of these, and all Solar System objects at any time see
And, for information on major planets

Meteor Showers

The main shower this month, the eta Aquarids, is much better seen from the southern hemisphere.  It is active between April 19th and May 28th, peak on the night of 5th/6th, ZHR 40 but far fewer from our latitude as the radiant is so low in the sky - it doesn't get above the horizon until just before dawn on that day.  The shower is said to show enhanced activity for about a week either side of the peak and the IMO says that there could be a couple of lesser peaks this year, one on 4th from 04.00 to 10.00 and the other on 6th between 12.00 and 20.00 - neither of which are likely to be much use to us.  These are swift moving meteors, parent comet the most famous of all - Halley.  The good news is that there is no Moon interference this year so, if you have clear skies,an unobstructed eastern horizon and a reliable alarm clock,, it might be worth looking between 01.30 and 03.30 on the morning of 6th.

Eta Lyrids:  active May 3rd to 14th, peak May 9th,  ZHR 3  (though some sources say it could be as high as 7).  These meteors, originating from debris left by comet C/1983H1 IRAS-Araki-Alcock, are best seen between 2am and dawn.

Alpha Scorpiids, active 20th April to19th May, peak 13th (or maybe 15th) ZHR 5.  Another one better seen from further south as the radiant is very low in our sky.  These are faint meteors, derived from asteroid 2004 BZ74.

The antihelion source may produce a few meteors in May, particularly towards the end of the month  The radiant moves through the northern part of Scorpio into southern Ophiuchus during May.  ZHR 2 - 4.

And there are a few daytime showers this month.  these can only be detected using radio or radar.  If anyone here does happen to have the right equipment for this,  full details can be found on the International Meteor Organisation website:

Comets

46P/Wirtanen and 38P/Stephan-Oterma are both still around and both still above the horizon for most of the night. They are in roughly the same area of the sky, moving between Leo and Leo Minor, however they are now very faint.  Wirtanen is expected to end the month around mag 16, Stephan-Oterma at 14.  

And finally
The big news last month was the first photograph of a black hole - or to be more accurate the first photo of the radiation surrounding a black hole.  Now is a good time to ty to spot its host galaxy, M87, a large elliptical located in Virgo.  It is situated between Virgo and Leo (lies on the line between between epsilon Virginis and beta Leonis, aka Denebola). It has an apparent magnitude of around 8 (sources vary as usual) and is classified as E1, meaning it isn't far off circular.  It is about 53.5 million light years from Earth and contains trillions of stars.  Of course, no scope can see the black hole, amateur scopes won't even be able to pick out the huge jets which emanate from it,  but the galaxy itself should be easy to find. 
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