Stargazing with Torbay Astronomical Society: A winter sky full of bright stars 

Torbay Weekly

Winter has always been a popular season for beginning an interest in astronomy and stargazing.

The long, dark nights offer plenty of opportunity for early evening observing and the nights that are clear tend to be crisp and clear with a clean, still atmosphere affording the most ideal conditions for seeing.

It also helps that many of the brightest stars we ever see from the northern hemisphere are on display throughout the night at this time of year.

Looking almost due south by 8pm, we can see the unmistakeable hourglass shape of Orion rising as the night goes on.

Look for the three stars in his belt as a guide.

Above and below are two stars fanned out wider than the belt itself.

If you flick your glance from the brightest at bottom right to the second brightest at upper left, you should be able to see indications that they are different colours.

The top left star is Betelgeuse, a red giant, and the bottom right star is Rigel a blue super-giant.

Hanging down from the belt are three fainter stars known as the sword; the middle one of these is not a star at all, but the brightest nebula or stellar gas cloud, visible from the Earth and is known as the Great Orion Nebula or M42; well worth a look with good binoculars or a small telescope.

The bright stars of Orion can be used as a signpost to identify other bright stars in the winter sky.

Imagine the line of Orion’s belt continuing upwards and to the right and it will bring you to another bright star at the head of a faint, but fairly large, 'V'-shaped cluster.

This is Aldebaran, the 'eye of the bull' and the cluster is called the Hyades and represents the head of Taurus.

Continue this line further and you come to another faint smudge; a close group of stars called the Pleiades or Seven Sisters.

Being able to see seven stars in this cluster is a test of good eyesight but in even a small telescope you can see up to 200 stars.

Follow the line of Orion’s belt back down and behind the constellation to the left and you will come to the bright star Sirius, the 'Dog Star' in the constellation of Canis Major.

This star is actually the brightest ever seen in the northern hemisphere but is always low in the sky, so it seems to twinkle and sparkle different colours.

This is purely an effect caused by the Earth’s atmosphere as we look through denser layers of air near the horizon.

Observations of this star enabled the ancient Egyptians to predict the annual flooding of the Nile.

Now imagine a line extending along the top of Orion from right to left and beyond.

This leads to another bright star called Procyon which is in the constellation of the little dog, Canis Minor.

Another imaginary line, this time from Rigel at bottom right, through Betelgeuse at top left and beyond leads you to two stars of similar brightness.

These are known as Castor and Pollux, the Twins and the box shape of stars hanging below them is Gemini.

One more imaginary line from Rigel at bottom right up through the star at top right (this star is called Bellatrix) and carried on about three times the length of Orion will bring you to a very bright star called Capella.

This star is in the constellation of Auriga - roughly an inverted pentagon.

Many clusters are contained within this shape and is worth sweeping with binoculars or a small telescope.

The Star Chart

The sky will look like the chart on January 7 at 9pm and again on January 21 at 8pm. And four minutes earlier on each successive night e.g. 8.56 on January 8.

To use the chart hold it above your head while facing south so that you can look directly from the chart to the sky.

Skynotes

Please note all times given in this article are in GMT and as the clocks have changed that is the current time.

Sun: At the start of the month there is just eight hours of daylight but as January progresses the length of day will increase by 1 hour and 15 minutes.

Mercury: Mercury is visible in the evenings seen in the background constellation of Sagittarius. The best time to see Mercury will be on January 7 when it is at Greatest Eastern Elongation - farthest distance from the Sun from our point of view - and will set 100 minutes after the Sun.

Venus: Venus reaches Inferior Conjunction - so lies between the Earth and the Sun - on January 9, so is not visible until the second half of this month when it will appear in the morning sky 60 minutes before sunrise and two hours before the Sun at the end of the month.

Mars: Mars is now a morning object seen against the background stars of Ophiuchus. It is now quite faint and difficult to observe.

Jupiter: Jupiter now lies very low in the south west and is no longer easily observed.

Saturn: The ringed planet is now seen in the evening twilight and is not readily observable.

Uranus and Neptune: Uranus is visible all night long and is seen against the background stars of Aries and close to the Pleiades star cluster. At magnitude 5.8 it is visible in binoculars. Look for a tiny greenish disc compared to the pinpoints which are the stars. Neptune is seen against the background stars of Aquarius - below the asterism known as the Square of Pegasus. At magnitude 7.8 it will require large binoculars or a small telescope to find it. Neptune displays a smaller and truly blue disc compared to that of Uranus although it will appear only as a bluish star to most small instruments

Meteor shower: The only meteor shower this month occurs from January 1 to 6. The meteors seem to radiate from a point near the end of the handle of the Plough but is known as the Quadrantids meteor shower as it is named after a now defunct constellation, Quadrans Muralis.

Comet: Comet Leonard is predicted to be the brightest comet of 2021. The comet may reach a peak of activity and brightness when it arrives at its closest point to the Sun (perihelion) on January 2. The comet can be found low in the south west and should be visible to the naked eye.

The New Moon occurs on January 2 with First Quarter on January 9, Full Moon then follows on January 17 and Last Quarter on January 25.

Data supplied by Simon Harding, Observations Secretary Torbay Astronomical Society

Diary Dates

The next meetings of the Torbay Astronomical Society, complying with the current Covid regulations, will be held at Torquay Boys' Grammar School on January 6.

An observational evening will be held in Room PL4 and the observatory, weather permitting, when members will be delighted to provide views of the objects discussed in this article.

In the event of bad weather, short talks and videos will be presented alongside informal discussion and an opportunity to get to know the society.

And on January 20, Martin Lunn will present a talk entitled 'A Very British Meteorite'.

Visitors and prospective members are especially welcome.

Talks will also be available online via Zoom.  For details, contact the TAS secretary on astrosecretary@gmail.com

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