Eye on the Night Sky over Whitby

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Planetary Skylights

Mars stubbornly lingers in the evening sky above the WSW horizon and doesn’t actually set until after 7pm.

Telescopically, it’s a case of ‘move along, nothing to see’, the disc being very small, but at least you can point it out to friends. The moon lies close by on the 24th & 25th.

Jupiter is now rising well before midnight, a conspicuous presence across in the east by 9.30pm at the start of December and 8pm at the end, by which time it is well placed for observation.

Telescopically, Jupiter is a wonderful spectacle with its attendant major moons and ‘banded’ disk, a real Christmas treat. After midnight, Jupiter will be riding high to the south.

The king of the planets actually resides just ahead of the ‘sickle asterism’ in Leo and not far from Regulus, its chief star. The moon lies near Jupiter and Regulus on the 9th.

During the last week of December first brilliant Venus and then elusive Mercury crawl up into the evening sky. Look for them low to the WSW horizon 45 minutes after sunset.

Both will be better placed as we head into the New Year.

Finally Saturn returns to the early morning sky by mid December and is visible low to the ESE by 6.30am.

The moon passes close by on the 19th and 20th. An early morning Christmas treat.

Meteor activity reaches a peak at this time of year and given clear skies the chance of spotting a shooting star or two should be quite high.

Considered now to be the most prolific annual meteor shower, the Geminids are active from December 7-16, reaching a peak on December 14.

Unlike the majority of meteor showers, which are associated with comet debris, Geminids stem from debris shed by a strange object that may be a dead comet or small asteroid called Phaethon.

This object passes within 10 million miles of the Sun and over time has deposited material over great swathes of the inner solar system. However it is only within the last 100 years that Geminid activity has increased to the levels recorded today with Earth passing through a much denser debris strand, a situation that will only last another 100 years.

The shower radiant lies close to Castor, the upper most of the ‘twin’ stars in Gemini visible in the east by 9pm. Under ideal conditions the Zenith Hourly Rate (ZHR) can reach well over 100, however observed rates are always substantially lower than this, so expect around 40 per hour during the early morning hours of the 14th.

Really bright Geminids can sometimes appear green or orange in hue.

Later in the month the Ursids (active Dec 17-25) peak on Dec 22/23 with hourly rates of 8-12 normal. Occasionally Ursids produce strong outbursts. The radiant lies close to the Great Bear.

The Sun reaches its lowest position in the sky on December 21 this year; the date of the winter solstice, by which time the Sun arcs little more than 12 degrees above S horizon at local noon from our latitude.

With the northern hemisphere tilted away from the Sun, useful daylight then amounts to just 7 ½ hrs, the shortest day. Latest sunrise and earliest sunset do not however occur on the 21st.

The Sun rises latest near the end of December (27 or 28) and sets earliest mid-month (15 or 16).

Astronomically speaking the winter solstice also marks the first day of winter in the northern hemisphere, but in a few weeks, daylight will once again start to lengthen in duration.

Now that is cause for celebration! What shall we call it ... mmm!

It’s been quite a while since a robotic lander mission caused such huge interest, even excitement amongst the general public, but the fortunes of Philae at comet 67P certainly did just that.

This was a drama played out over 300 million miles away with Up’s and Down’s a plenty, (certainly Philae experienced a few) and left us on the edge of our seats with Philae near the edge of somewhere (mission controllers still are not sure exactly) Approximately 8o% of the scientific program was completed, the results of which are still being analysed.

What we do know is that Philae is now in hibernation mode, starved of sunlight to power the solar panels. Perhaps, as the comet heads into the inner solar system its orientation will alter, allowing sunlight to illuminate the location of Philae’s final resting place. We shall see in the coming months.

I have a hunch the ride is not yet over!

The winter night sky is to my mind of nature’s the finest vistas. An observer is treated to an array of brilliant stars and imposing constellations, rich in mythology and observational interest, whether using binoculars, a telescope or just the naked eye.

Located at the heart of this glittering tableau stands the mighty hunter, Orion, which strides majestically across the southern aspect of the sky.

Its main pattern is quite distinct; a sloping line of three stars set in the midst of a larger rectangle bounded by four others.

Two of these stars, in opposing corners are real super luminaries’. Searing blue/white Rigel illuminates the bottom right of the rectangle and is perhaps 60 – 70,000 times more luminous than our Sun.

Opposite Rigel, in the “red corner” (top left) lies Betelgeuse, a red super-giant star nearing the end of its evolution, its deep orange hue a clear indication of its age and cooler temperature.

Betelgeuse has ballooned to gargantuan proportions, over 400 million miles in diameter. Put another way, if Betelgeuse were at the heart of our solar system it would extend out beyond the orbit of Mars.

Of the naked eye stars visible in the night sky, Betelgeuse is possibly the strongest candidate to end its days as a supernova, tearing itself apart in a cataclysmic explosion that will light up our sky for weeks on end, hopefully sooner than later.

A few million years in the future Rigel will also follow suit.

Situated a little way below the three stars marking Orion’s belt is one of the heavens great show piece objects. Seen clearly as a misty smudge through binoculars, the Orion nebula is the nearest region of stellar birth around 1,200 light years distant.

Within this nebula, denser clouds of gas and dust are squeezed by gravity to form proto-stars, which ‘switch on’ once the core reaches a critical temperature allowing nuclear fusion to commence. A star is born.

Telescopically the nebula is quite breathtaking, a swirl of nebulous cloud at the heart of which reside the Trapezium stars, the four “bully boys” of this stellar crèche little more than 10 million years old.

Bearing down on Orion to his upper right is Taurus the Bull, whose eye is marked by fiery hued Aldebaran in the ‘V’ shaped Hyades star cluster, although it is not a true member.

A little further west, the Pleiades star cluster (Seven Sisters) is a beautiful sight in binoculars or low power eyepiece. Riding high to the south and above Taurus are the stars of the charioteer - Auriga, highlighted by bright Capella, located almost overhead.

Upper left of Orion stand the Twins of Gemini, marked by the two conspicuous stars, Castor and Pollux. Castor, the most northerly of the pair, is slightly fainter than twin brother Pollux which shines with a pale amber lustre. Although Castor appears solitary, in reality it is a multiple system of which the brightest two components may be separated in a modest scope, given stable atmospheric conditions.

Two hunting dogs, Canis Major and Canis Minor, accompany Orion, dutifully following their master across the heavens. Canis Major is overwhelmed by the sparkling presence of Sirius, the brightest star in the entire night sky.

The lesser dog, Canis Minor is also distinguished by a conspicuous star- Procyon, located left of Orion and below Gemini. The prominence of both stars is down to proximity; 8.6 and 11 light years respectively.

The dog’s quarry, the timid celestial hare of Lepus, may be traced crouching below Orion and above the southern horizon. Forever separating master and greater dog from the lesser one, look for the faint glow of the winter Milky Way which passes down to the left of Orion.

No matter whether you are an experienced observer, or perhaps have just acquired a pair of binoculars or a telescope, the jewels of Orion and his retinue are a joy to explore time and time again.

Wrap up well, find somewhere dark and enjoy.

Open nights at Bruce Observatory this month are December 7, 14, and 21 and 28, from 7pm. clouds permitting. Ring Mark beforehand if unsure, on 605516.

For more information visit www.whitby-astrononers.com