18th October 2018
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Stargazing: Halfway through dark sky season

, by , in Features

THE LAST month of the year, the month in which the skies start to get lighter as the sun starts its journey north in the sky. We are half way through the dark sky season in Shetland. The winter solstice is at four minutes past midday on the 21st.

Full moon is on the 12th and the New moon is on the 27th.

Sunset – 10pm

The Moon will be out of the way from the 16th to 31st.

After the sun sets look low down to west of south and you should see the planet Venus and slightly lower and further west the planet Jupiter. Being that low to the horizon with the light travelling through a lot of the earth’s atmosphere you will not have great views but you should be able to see the phase of Venus and the moons of Jupiter with the aid of binoculars.

If you want to try and find the planet Uranus then looking due south, with the aid of binoculars and a map, around 6pm is a good time. Neptune is really a bit too low for easy viewing.

10pm-2am

The Moon will be out of the way from the 1st to 6th and 20th to 31st. Around midnight Saturn rises in the east.

Whether with the naked eye or any size of optical instrument, to me, the grandest constellation is in the southeast and moving round to the south at midnight – Orion. Look at the nebula M42 at the tip of “The Sword”. Fuzzy to the naked eye but in photographs, even for normal cameras, it is magnificent.

2am-sunrise

The Moon will be out of the way from the 1st to 8th and 22nd to 31st.

Saturn is due south at around 6am. A small telescope may show the rings whose plane is presently quite flat so they may not be too easy to see at all.

Due to the eccentric nature of the earth’s orbit the latest sunrise is not on the day of the solstice. To the nearest minute the latest sunrise is at 9:09am and occurs on the mornings of the 22nd to 31st inclusive.

Similarly with the earliest sunset that can be found at four minutes to three o’clock on the afternoons of the 14th to 18th.

As for which day has the least daylight, that is somewhere between the 20th and 23rd with the difference being in the seconds rather than minutes each day.

Working out the times of sunrise and sunset are a useful application of orbital mechanics and if you have an interest in maths you could probably find out how to do it for yourself rather than use a computer program like myself.

If you really do enjoy mathe­matics then your skill could take you in the direction of an amateur satellite hunter, Kevin Fetter, from America. He is reported on the SpaceWeather website for imaging a tool bag that was let go of by an astronaut working on the Inter­national Space Station. He managed to video the tool bag from earth! Not only that but the website has a tracking service that gives visible satellite fly-bys. So to see the Space Station use the Heavens Above website and for other objects, including orbiting tool bags, use the SpaceWeather site.

Much of the information about forthcoming events in the sky can now be found on the internet so if you have any ideas how those who do not have internet access can get this information then please tell me – the sky is for everyone, not just those with a computer.

Unfortunately the sky was not clear last month for the Leonid meteor shower as reports are that it brightened up around dawn on the 17th. Hopefully it will be clear for this month’s Geminids as they are the year’s most constant meteor shower.

Most meteor showers are associated with a comet but in 1983 a new asteroid was found and later seen to have the same orbit as the Geminid Meteors. Orbital mech­anics were used to show that the asteroid 3200 Phaethon was the parent body of the dust of the meteor shower.

The Geminids peak on the morning of the 13th with up to 20 meteors an hour but activity can be seen from the 7th to the 16th at a rate of one meteor per hour. The problem though will be the Moon as it is full on the 12th and the next night is sitting right in the middle of Gemini! If the sky permits then look in the direction of the Pleiades and hopefully you will see the odd bright meteor.

The SpaceWeather website is quite good at forecasting auroras a few days in advance. As you read this the previous few nights may have had a good display. But do not rely on the internet, if the sky is partially clear then go out and look as not all displays of the Northern Lights are predicable.

Being dark for nearly 18 hours each night in December gives plenty of time if the clouds clear to look at the sky. Spend time just getting to know the constellations and then use binoculars to search out the “fuzz-balls” that are the Messier objects – so named because Charles Messier catalogued them in the late 18th century as objects that may be confused with a comet.

Have a wonderful Christmas and hopefully with clear skies.

Chris Brown