December Skylights
Jupiter and Saturn are once again the main attraction this month, coming together in a stunning close conjunction before they slip below the horizon after their ten-month long apparition.
Over the course of the year Jupiter has edged ever closer to Saturn and starts December just over 2 degrees ahead of Saturn. You will locate them low to the SW, around 4.30–5pm. Jupiter is still conspicuous, Saturn, residing to the upper left, is not quite so. By mid-month the pair are separated by just over half a degree and are joined by a crescent moon on the 17th, making for a fine sight. As the two planets drop closer to the SW horizon, the separation diminishes still further, and by the 21st it is a miniscule 0.06 degrees, or just 6 arc minutes.
To the eye, Jupiter and Saturn will appear almost as one, with Saturn being somewhat overwhelmed by Jupiter. Binoculars will show them side by side, whilst larger binoculars hint at the view through a telescope. And what a view! Even with a very modest telescope at medium to high power, both planets will fit nicely in the same field of view making for a truly spectacular sight. They appear almost as close the following evening, so a second chance beckons. Through a telescope, look for the banding on Jupiter, the Galilean moons, and even the great red spot (visible on the 20th). Saturn has the wonderful ring system, with Titan, its largest moon, visible as a speck nearby. Do not however expect to see sharp detail: with both nearing the horizon, ‘seeing’ will be rather poor – ‘a bit wobbly’. Observe as soon as twilight drops, 4.15pm onwards.
Do make the most of any opportunity to view this stunning spectacle – naked eye, binoculars or with a telescope – a fitting finale to the observing year and one which won’t be repeated until November 2040.
Mars, although still very conspicuous to the naked eye, diminishes considerably in brightness and apparent diameter during December. The good news for observers is that Mars is already riding high to the south by 7pm, clear of the ‘unsteady seeing’ above the horizon. From 6th–13th the large, dark, fin-shaped surface detail of Syrtis Major will be presented towards us and should be noticeable with medium/high power magnification in average sized telescopes (4-inch). The moon lies below Mars on the 13th.
In the dawn sky after a fine morning apparition, Mercury is a difficult object to spot at the start of December: very low to the horizon, due SE, around 7.30am. Use binoculars to ‘pull’ it out of the twilight. By the 5th it is lost. Also in the SE, but somewhat higher and very much brighter, Venus remains a conspicuous object to the naked eye. It is slowing sinking back towards the rim, being joined by a waning crescent moon on the 12th. View around 7.30am.
December Meteors
Meteor activity reaches a peak at this time of year and given clear skies the chance of spotting a shooting star is reasonably high. Considered to be the most prolific annual meteor shower, the Geminids are active 7–16 December, reaching a peak this year in the morning hours of the 14th. Geminid debris stems from a small asteroid called Phaethon which, over time, has deposited material over great swathes of the inner solar system. Brighter Geminids regularly produce long luminous trails, sometimes green or orange in hue. The shower radiant lies close to Castor, in Gemini, visible in the east by 6pm. Under ideal conditions the Zenith Hourly Rate (ZHR) can exceed 100 plus; however, observed rates are always lower. With no moon to hamper this year, conditions (weather aside) will be ideal and numbers should be around the 40–60 mark in the early morning hours of the 14th and perhaps half this pre-midnight on the 13th.
The Ursids are active 17–25 December with maximum occurring on 22nd/23rd. Rates of 8–12 are normal, but occasionally Ursids produce strong outbursts.
The Winter Solstice
The Winter Solstice falls on 21 December this year, when the Sun reaches its lowest position in the sky (just over 12 degrees above S horizon at local noon). The tilt of the northern hemisphere away from the Sun has now reached its maximum and useful daylight amounts to just 7½ hours – the shortest day. Latest sunrise and earliest sunset, however, do not occur on this date. The Sun rises latest around the 28th and sets earliest mid-month. Astronomically speaking the winter solstice marks the first day of winter in the northern hemisphere, but hey, this is Britain, so expect a heat wave!
A ’Scope is not just for Christmas!
With Christmas fast approaching you may be considering investing in some type of ‘optical aid’ for someone who has an interest in the night sky, or perhaps you yourself are hoping to purchase an item of astro’ equipment, but are unsure on just what. Here then, are a few thoughts, ideas and tips, which may be of assistance.
If you have a limited budget, binoculars are an ideal gift, providing a portable means of enjoying both the beauty of the heavens and our terrestrial surroundings. When choosing a pair of binoculars intended primarily for astronomical purposes, especially for a younger person, look for an eyepiece to objective ratio of roughly 7, matching the diameter of the eye pupil, such as 7 x 50 or 8 x 56 binoculars. This ratio becomes less critical for terrestrial viewing or for anyone over 40. I would avoid zoom type binoculars, which may seem excellent value but compromise on optical quality unless you fork out serious money. Binoculars that employ BAK 4 prisms have multi-coated surfaces, though be wary of models with garish coloured optics.
Expect to pay around £35–£50 for an adequate pair of typical 7 or 10 x 50 binoculars and £60–£150 for something more refined. Larger models, such as 11 x 80, 20 x 100 etc, start from around £120 upwards and will require a tripod to observe satisfactorily. Image stabilising binoculars are actually pretty good – but expensive (several hundred pounds). When purchasing from a shop (may be difficult this year) try before you buy. Focus should be smooth, the image sharp to the edge and they should be comfortable in the hand.
If you are looking to invest in a telescope the choice can seem quite bewildering. Ask yourself a few questions. Who is the scope for, and if it is intended purely for astronomical purposes how serious are they? Is portability an issue? And what is the budget? Of the different types of scope, bear in mind that a reflecting telescope (one that employs mirrors) is solely used for astronomical purposes and is of little use for terrestrial viewing. Reflector telescopes have the eyepiece and focuser positioned near the top end of the tube, in line with the secondary mirror, which is housed just inside the open end of the tube.
A refractor (with objective lenses) may be used for terrestrial viewing as well as astronomical, however in pure astronomical instruments the image is flipped so that writing looks reversed. Refractors have the focus and eyepiece at one end of the tube and an unobstructed lens at the other, creating a sealed system. Catadioptrics such as the Cassagrain design are also a sealed system with the eyepiece holder on the rear of the tube assembly, but use a combination of mirrors and lenses to fold the optical light path. Catadioptric are compact and portable, but more expensive. Many instruments above £500 often employ GOTO tracking to facilitate locating objects, locking on and tracking at the touch of a button . . . normally several, actually. These mounts are highly useful, but can be temperamental sometimes.
A ‘beginners’ or child’s 60–75mm refractor can be purchased for as little as £70–£100, a basic entry level 114mm reflector for £120. Half decent quality 80–90mm refractors start from £150, and £280 plus will buy you a 100mm refractor. More robust 110mm (4½-inch) and 150mm (6-inch) reflecting scopes start from £180. The most cost-effective type of astronomical scope is the Dobsonian reflector; they are simple to set up and use and can be picked up for as little as £180 for a 150mm (6-inch) aperture – an excellent buy. Catadioptrics (90mm) start at £260, but expect to pay above £1,000 for anything over 200mm (8-inch). Steer clear of small and apparently cheap GOTO instruments; from my experience they have severe limitations.
Refractors, reflectors (excluding Dobsonian’s) and Cassagrains, are usually married to an azimuth or equatorial mount. If you are looking for something simple, azimuth mounts are good for refractors. Steer clear of small aperture reflecting instruments on feeble looking equatorial mounts . . . spend a few more pounds and get a Dobsonian. A wobbly mount renders even the best optical system useless.
You will find these sites useful: www.opticalvision.co.uk / www.rothervalleyptics.com / www.astroshop.eu . . . or for somewhere more local (Northallerton): www.grovers.biz
Remember, ‘a scope is not just for Christmas’. Actually, looking around the astro retail scene, it looks as though many suppliers are experiencing difficulty in getting stock in, so be patient. This year, that scope may be in time for Easter!
If you require further guidance please contact spanton33@talktalk.net. Also visit www.whitby-astronomers.com
Have a great ‘winter solstice festival’ . . . as good as Covid restrictions allow!
Mark Dawson,
Whitby and District Astronomical Society
WDAS usually meets in room H1, Caedmon College, Normanby campus (Whitby College). New members most welcome.
www.whitby-astronomers.com
.
Over the course of the year Jupiter has edged ever closer to Saturn and starts December just over 2 degrees ahead of Saturn. You will locate them low to the SW, around 4.30–5pm. Jupiter is still conspicuous, Saturn, residing to the upper left, is not quite so. By mid-month the pair are separated by just over half a degree and are joined by a crescent moon on the 17th, making for a fine sight. As the two planets drop closer to the SW horizon, the separation diminishes still further, and by the 21st it is a miniscule 0.06 degrees, or just 6 arc minutes.
To the eye, Jupiter and Saturn will appear almost as one, with Saturn being somewhat overwhelmed by Jupiter. Binoculars will show them side by side, whilst larger binoculars hint at the view through a telescope. And what a view! Even with a very modest telescope at medium to high power, both planets will fit nicely in the same field of view making for a truly spectacular sight. They appear almost as close the following evening, so a second chance beckons. Through a telescope, look for the banding on Jupiter, the Galilean moons, and even the great red spot (visible on the 20th). Saturn has the wonderful ring system, with Titan, its largest moon, visible as a speck nearby. Do not however expect to see sharp detail: with both nearing the horizon, ‘seeing’ will be rather poor – ‘a bit wobbly’. Observe as soon as twilight drops, 4.15pm onwards.
Do make the most of any opportunity to view this stunning spectacle – naked eye, binoculars or with a telescope – a fitting finale to the observing year and one which won’t be repeated until November 2040.
Mars, although still very conspicuous to the naked eye, diminishes considerably in brightness and apparent diameter during December. The good news for observers is that Mars is already riding high to the south by 7pm, clear of the ‘unsteady seeing’ above the horizon. From 6th–13th the large, dark, fin-shaped surface detail of Syrtis Major will be presented towards us and should be noticeable with medium/high power magnification in average sized telescopes (4-inch). The moon lies below Mars on the 13th.
In the dawn sky after a fine morning apparition, Mercury is a difficult object to spot at the start of December: very low to the horizon, due SE, around 7.30am. Use binoculars to ‘pull’ it out of the twilight. By the 5th it is lost. Also in the SE, but somewhat higher and very much brighter, Venus remains a conspicuous object to the naked eye. It is slowing sinking back towards the rim, being joined by a waning crescent moon on the 12th. View around 7.30am.
December Meteors
Meteor activity reaches a peak at this time of year and given clear skies the chance of spotting a shooting star is reasonably high. Considered to be the most prolific annual meteor shower, the Geminids are active 7–16 December, reaching a peak this year in the morning hours of the 14th. Geminid debris stems from a small asteroid called Phaethon which, over time, has deposited material over great swathes of the inner solar system. Brighter Geminids regularly produce long luminous trails, sometimes green or orange in hue. The shower radiant lies close to Castor, in Gemini, visible in the east by 6pm. Under ideal conditions the Zenith Hourly Rate (ZHR) can exceed 100 plus; however, observed rates are always lower. With no moon to hamper this year, conditions (weather aside) will be ideal and numbers should be around the 40–60 mark in the early morning hours of the 14th and perhaps half this pre-midnight on the 13th.
The Ursids are active 17–25 December with maximum occurring on 22nd/23rd. Rates of 8–12 are normal, but occasionally Ursids produce strong outbursts.
The Winter Solstice
The Winter Solstice falls on 21 December this year, when the Sun reaches its lowest position in the sky (just over 12 degrees above S horizon at local noon). The tilt of the northern hemisphere away from the Sun has now reached its maximum and useful daylight amounts to just 7½ hours – the shortest day. Latest sunrise and earliest sunset, however, do not occur on this date. The Sun rises latest around the 28th and sets earliest mid-month. Astronomically speaking the winter solstice marks the first day of winter in the northern hemisphere, but hey, this is Britain, so expect a heat wave!
A ’Scope is not just for Christmas!
With Christmas fast approaching you may be considering investing in some type of ‘optical aid’ for someone who has an interest in the night sky, or perhaps you yourself are hoping to purchase an item of astro’ equipment, but are unsure on just what. Here then, are a few thoughts, ideas and tips, which may be of assistance.
If you have a limited budget, binoculars are an ideal gift, providing a portable means of enjoying both the beauty of the heavens and our terrestrial surroundings. When choosing a pair of binoculars intended primarily for astronomical purposes, especially for a younger person, look for an eyepiece to objective ratio of roughly 7, matching the diameter of the eye pupil, such as 7 x 50 or 8 x 56 binoculars. This ratio becomes less critical for terrestrial viewing or for anyone over 40. I would avoid zoom type binoculars, which may seem excellent value but compromise on optical quality unless you fork out serious money. Binoculars that employ BAK 4 prisms have multi-coated surfaces, though be wary of models with garish coloured optics.
Expect to pay around £35–£50 for an adequate pair of typical 7 or 10 x 50 binoculars and £60–£150 for something more refined. Larger models, such as 11 x 80, 20 x 100 etc, start from around £120 upwards and will require a tripod to observe satisfactorily. Image stabilising binoculars are actually pretty good – but expensive (several hundred pounds). When purchasing from a shop (may be difficult this year) try before you buy. Focus should be smooth, the image sharp to the edge and they should be comfortable in the hand.
If you are looking to invest in a telescope the choice can seem quite bewildering. Ask yourself a few questions. Who is the scope for, and if it is intended purely for astronomical purposes how serious are they? Is portability an issue? And what is the budget? Of the different types of scope, bear in mind that a reflecting telescope (one that employs mirrors) is solely used for astronomical purposes and is of little use for terrestrial viewing. Reflector telescopes have the eyepiece and focuser positioned near the top end of the tube, in line with the secondary mirror, which is housed just inside the open end of the tube.
A refractor (with objective lenses) may be used for terrestrial viewing as well as astronomical, however in pure astronomical instruments the image is flipped so that writing looks reversed. Refractors have the focus and eyepiece at one end of the tube and an unobstructed lens at the other, creating a sealed system. Catadioptrics such as the Cassagrain design are also a sealed system with the eyepiece holder on the rear of the tube assembly, but use a combination of mirrors and lenses to fold the optical light path. Catadioptric are compact and portable, but more expensive. Many instruments above £500 often employ GOTO tracking to facilitate locating objects, locking on and tracking at the touch of a button . . . normally several, actually. These mounts are highly useful, but can be temperamental sometimes.
A ‘beginners’ or child’s 60–75mm refractor can be purchased for as little as £70–£100, a basic entry level 114mm reflector for £120. Half decent quality 80–90mm refractors start from £150, and £280 plus will buy you a 100mm refractor. More robust 110mm (4½-inch) and 150mm (6-inch) reflecting scopes start from £180. The most cost-effective type of astronomical scope is the Dobsonian reflector; they are simple to set up and use and can be picked up for as little as £180 for a 150mm (6-inch) aperture – an excellent buy. Catadioptrics (90mm) start at £260, but expect to pay above £1,000 for anything over 200mm (8-inch). Steer clear of small and apparently cheap GOTO instruments; from my experience they have severe limitations.
Refractors, reflectors (excluding Dobsonian’s) and Cassagrains, are usually married to an azimuth or equatorial mount. If you are looking for something simple, azimuth mounts are good for refractors. Steer clear of small aperture reflecting instruments on feeble looking equatorial mounts . . . spend a few more pounds and get a Dobsonian. A wobbly mount renders even the best optical system useless.
You will find these sites useful: www.opticalvision.co.uk / www.rothervalleyptics.com / www.astroshop.eu . . . or for somewhere more local (Northallerton): www.grovers.biz
Remember, ‘a scope is not just for Christmas’. Actually, looking around the astro retail scene, it looks as though many suppliers are experiencing difficulty in getting stock in, so be patient. This year, that scope may be in time for Easter!
If you require further guidance please contact spanton33@talktalk.net. Also visit www.whitby-astronomers.com
Have a great ‘winter solstice festival’ . . . as good as Covid restrictions allow!
Mark Dawson,
Whitby and District Astronomical Society
WDAS usually meets in room H1, Caedmon College, Normanby campus (Whitby College). New members most welcome.
www.whitby-astronomers.com
.
