The night sky in May 2015

posted 29 Apr 2015, 11:39 by Pete Collins   [ updated 29 Apr 2015, 11:50 ]
by Anne Holt

Sunset - May 1st 20.36, May 31st 21.24

Constellations


What can we see in the night sky in May?  For those of us who attended the Hay Dark Sky Festival in April, the answer will be not a lot from Manchester compared to what we saw there - with the naked eye, at least. Still, with only the brighter stars visible it makes it easier to recognise the constellation shapes!

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 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


Venus,  in Taurus, mag minus 4.2. Still the brightest thing in the night sky after the moon and quite high up for the earlier part of the night.  Sets about 4 hours after the sun.  At month end it will appear to pass close by Castor and Pollux in Gemini.

Jupiter, in Cancer, mag minus 2. High in the sky as it darkens at the start of the month, but quite low by late May, when it will be setting around midnight.
The apparent gap between Jupiter and Venus is closing, by month end it will be 19 degrees. 

Mercury, in Taurus, is an evening object. At the start of May it is visible, in the twilight, at a magnitude of around minus 0.3 but it will fade rapidly as it approaches greatest eastern elongation on 6th.  On 19th it will be 9.25 degrees to the left of the 3% lit crescent moon, very low in the west, about 30 minutes after sunset but will have dimmed to 2. 7 and be very difficult to spot.  It won't be visible at the end of the month, as it approaches inferior conjunction on 30th.

Saturn, in Scorpio moving into Libra,  mag 0.1. It reaches opposition on 23rd, though it is still very low in the sky.  The rings are tilted by 24.5 degrees and will appear noticably brighter than usual because the particles of which they are made do not cast visible shadows at this time. At midnight on 6th it will be 3.75 degrees west of the waxing gibbous moon.

Neptune, in Aquarius, mag 7.9. Hardly visible this month, rising at 3am by the end of the month but remaining very low in the south east.

Mars and Uranus are not visible.

Meteor showers

The Eta Aquarids,  dust particles from Halley's comet,  are active between April 19th and May 28th,  peaking on the night of May 6th/7th.  Fast moving meteors, many of which leave persistent trails. Because the radiant is below the celestial equator they are more numerous from the southern hemisphere but have a ZHR of 10 to 30 from our latitude.  Best seen just before dawn but, unfortunately, this year the moon will be just past full, so only the brightest will be visible.

The Camelopardalids,  a new shower, are remnants from Comet 209P/Linear, and have a very short peak on May 24th. .  Hundreds of meteors were predicted for May 2014 but it was very disappointing - only a few were seen, so who knows what will happen this year?
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