24th May 2018
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Stargazing: Time to look out the sun-lounger, wrap up warm and watch a meteor shower

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The skies have had few meteor showers over the past two months but the next two months brings 15. It is time to check the condition of your sun-lounger and collect together all those old clothes in which to wrap up and keep warm.

Full darkness ends on the 20th April but the sky will still be dark enough to watch the planets for several weeks after, with astronomical twilight lasting until 9th May.

In April Full Moon is on the 25th and New Moon is on the 9th. In May the main phases have Full Moon on the 9th and New Moon on the 24th.

Evening – Sunset to 1am

April is a good time to catch the planet Mercury, the planet that orbits closest to the Sun. From the middle of the second week in April, not long after the Sun has set, start looking low down on the west-north-western horizon.

While Mercury is always brightest at the beginning of an evening apparition it is at its closest to the horizon. Over the nights of April it rises higher in the sky. The photographic moment of this apparition comes on the evening of 26th April when a less than two day old Moon is just above Mercury.

The apparition continues on into May with Mercury getting lower in the sky and fainter night after night. If you have never seen Mercury then this is a good showing. If you have seen Mercury before you will want to get out on the spring evenings and have another look.

Saturn is still prominent in the evening sky so do take a look at the ringed planet.

Morning – 1am to sunrise

As Saturn sets in the west in the early morning then the giant planet Jupiter rises. It is low in the sky as seen from Shetland but big enough that the Jovian moons will be visible in binoculars.

April into May is the meteor season so if you have internet access at home, work or the library then a search for meteor showers may bring you to the Association of Lunar and Planetary Observers list of meteor showers. The dates meteors from these collections of dust can be are obviously written here as month/day.

VIRGINIDS 03/01-04/15 DELTA PAVONIDS 03/11-04/16 LIBRIDS 04/15-04/30 LYRID 04/15-04/28 APRIL FIREBALLS 04/22-04-30 PI PUPPIDS 04/15-04/28 ALPHA BOOTIDS 04/14-05/12 MU VIRGINIDS 04/01-05/12 OMEGA CAPRICORNIDS 04/19-05/15 ETA AQUARIDS 04/19-05/28 ALPHA SCORPIIDS 05/01-05/31 BETA CORONA AUST. 04/23-05/30 OMEGA SCORPIIDS 05/23-06/15 ARIETIDS 05/22-07/02

The most numerous of these is the Lyrids and this year the Moon will be just a few days old when it peaks on the 22nd. The stand-by shower is the April Fireballs at the end of the month. I have had several reports of them over the last few years so if the night is warm, find yourself a site away from light pollution, and look up – you may be lucky.

Those wishing to photograph meteors also need luck but with a digital camera capable of several minutes of exposure time all you require is persistence. If a meteor shower is on then point your camera about 45 degrees from the radiant and just take image after image. You do not need a fancy drive just a tripod and a cable release – and a flask of coffee or tea!

Other moving objects in the sky to look out for are satellites and the International Space Station. Those with Internet access should go to the Heavens-Above website where timings can be found.

Something rare was seen in the middle of March this year, a solar halo complex. Why rare? It is not uncommon to see Sun Dogs and the ring around the Sun on which they lie. But the halo we normally see is made up of “common” flat ice crystals; this halo was made up of pyramidal shaped crystals that do not lie so neatly.

Now the normal halo is known as the 22 degree halo as that is its radius but the disorderly pyramidal crystals form a 9 degree halo and then a run of haloes at 18, 20, 22, 23 and 24 degrees. This unusual display shows the 9 degree halo, the Sun Dogs and a fuzz of the other halos.

Now if you want to know more about these haloes and other sky sights then do go to Les Crowley’s Atmospheric Optics website. And thank you to Les for identifying these unusual haloes and making this display one of the Atmospheric Optics pictures of the day (http://www.atoptics.co.uk/fz217.htm) Have a good summer – the column should return in August.

Chris Brown