Beginners - Starting out (see also FAQ page)
There are many good beginners guides to observing on the web, such as this and this. There is even an 'official' guide from the Royal Astronomical Society. You can also find many guides to the types of observing. The truly dedicated (who try hard enough) might even find a local evening class. However, all of these can be a bit 'theoretical', so we at MAS have tried to focus on some of the more practical aspects.
Beginners topics are often covered in our main meetings - see, for example, October 2015 meeting notes on Starting Astrophotography
The BBC2 Stargazing Live web pages
The Stargazing Live web pages hold lots of information useful for beginners. See especially How do telescopes work ? and the SGL guide to telescopes (PDF). You will find further advice below (and there is even a document - 'What telescope should I buy ?' - on our FAQ page) about telescope buying, however one thing we really recommend to 'beginners' is that you attend one of our meetings and get invited to our next observing session (we hold one every 3rd Friday, weather permitting) and 'try out' members telescopes before spending hundreds of £££'s on kit that may not suit you
MAS has held a public event 'in conjunction with' Stargazing Live ever since the series started in 2011 (our event is usually on the Saturday following the broadcast). Reports of how previous events turned out can be found on our Events page (the events are in January of each year).
The Google Sky Map app. is the 'new standard**' in graphical sky constellation 'painting' for Android users. This helps you learn your way around the night sky (members have been known to take a sneaky look at their Tablets before putting a name to even the most obscure objects in the night sky, thereby ensuring their 'expert' reputation). Also recommended is 'Night Sky Tools' (from Smoky Cogs), another free app., which provides a wealth of 'whats happening in the sky now' information for your current location.
**Stellarium, the desktop PC 'standard', is not free for Tablet users but does provide (slightly) more options (it may be possible to control a 'Go-To' telescope (via Bluetooth) from your Tablet using Stellarium, however modern telescopes supporting Bluetooth will come with their own 'app')
What you can expect to see in the night sky
In the suburban sky our eyes (if we are fortunate to have a good pair) will see roughly 1500 stars. This increases to about 5000 in a rural area away from the street lights. See the Campaign for Dark Skies maps or more detailed maps. The Philips Dark Skies map from Amazon is also a good source of more information on finding a darker location.
The easiest way to see more is to use binoculars; chances are, you already have a pair. They are indispensable, easy to carry around and will show you a wide area of sky (about 7 degrees) in more detail; revealing many interesting objects like nebulae, star clusters, comets and the moons of Jupiter.
As soon as you move into a darkened area, your eyes start to become accustomed to the reduced light. Your pupils open up to allow more light in and a chemical process takes place in our eyes to make them more sensitive. It is important to be dark adapted when viewing the night sky whether it be with the naked eye, binoculars or a telescope. The exception is the Moon. This is already bright and seeing it in a telescope will often spoil your dark adaptation. Not to worry though, your dark adaptation will return after 10 minutes, or you can buy filters to cut down the light if its a full moon for instance. Full dark adaptation may take 20 or 30 minutes.
The chemical responsible for enhancing our dark vision is destroyed by white light, but not red light (see diagram). This is why astronomers use red light torches (and why you are likely to hear shouts of "put that light out !" if you wave around a white light torch during an observing session)
The edges of the eye's retina are more sensitive to light and movement, but not to colour. When one looks away, or to the side, a star can appear brighter. This method allows faint stars to become visible when they were not seen by direct vision. Astronomers often look around the field of view to pick up faint stars or objects at the threshold of visibility. There is a good summary in this power point pdf
Warm clothing for winter nights
The stars tend to be 'sharper' during the winter nights (both because of the reduction in Sun 'sky glow' and the cooler air (so less 'thermal distortion') - but don't forget your thermal under-ware, socks and gloves, ski-boots, overcoat & hoody !
You will see binoculars reviewed in magazines and on the internet. Sky and Telescope has a article on the subject. Our Links page list a wide range of equipment suppliers, many of whom sell binoculars.
If you visit a specialist retail supplier (which is convenient, but usually much more expensive than Amazon etc) ask the sales person what he/she recommends for star gazing (often general shop staff will assume you are a bird watcher and try to sell you an expensive 'spotting scope' instead !).
Better, join MAS and attend our observing evenings - there will almost always be some-one with binoculars who will be only to happy to advise (and let you try theirs out first) before buying your own.
Apart from optical and build quality, some other features should be understood. Binoculars are specified by two numbers - eg "7 x 50" etc. The first number is the magnification, the second is the diameter of the front lens, which is called the "objective" or "object glass" (or just "OG" for short). The OG sets the amount of light gathered - and the more light you have, the higher the magnification you will get. Of course the higher the OG, the heavier the Binoculars - and those with an OG of 100 (or more) are a lot more expensive. Of course, higher magnifications also mean smaller fields of view.
Small size is one of the best attributes of binoculars - but don't buy binoculars with an OG less than 40mm (whilst fine for bird-watching in daylight, they won't gather enough light for star gazing) ! As a 'general rule' the best choices for night use will be 7 or 8 x40, 8x50 or perhaps 10 x50 or x60 (which is pushing it a bit). Sizes greater than 10x50 will usually too heavy for easy viewing and need to be supported by a tripod (or other device) - it's very hard to hold heavy binoculars steady, especially if the magnification is above about 8.
The view through any pair of binoculars will be improved if supported to minimise shake. A tripod mounting bracket is a common solution. Improvement can be made by using a parallelogram mount such as on this link by Graham Wood, or maybe purchased. Some other examples of binocular mounts here.
The exit pupil (given in mm) is sometimes found in the specification for binoculars. This is simply OG size divided by magnification and usually does not exceed 7mm and is typically 4 or 5mm. The exit pupil should be matched to your own dark adapted pupil size. The maximum size of the pupil decreases with the age (image licensed under a Creative Commons Attribution 3.0 License) of the observer (and is even worse for those with age related illnesses, such as diabetes). So 10x50 or 15x80 are fine for most people. Some wonderfully views of the Milky Way can be had with say 8 x 50s from the darkness of mid-Wales, moors and National parks.
This value essentially indicates 'how close' your eye has to be to the eyepiece glass to see anything. For those wearing glasses, the 'longer' the eye relief the better (many quality binoculars have rubber 'eye caps' that can be 'folded down' for those with spectacles)
NB. Don't confuse the exit pupil or eye relief specification with the actual diameter of the eyepiece, although you will quickly discover that cheap binoculars with inferior optics have much smaller eyepiece lens diameter than any with decent optics. The smaller the eyepiece diameter, the harder it is to actually 'line up' your eye to actually see anything
Moving on to telescopes
The move from binocular to telescope is a leap in performance. A history of the telescope can be found here. With a telescope comes many advantages:
1) Variable (and higher) magnifications, allowing the observer to see planets as disks and detail on the disk,
2) greater light gathering ability - allowing much fainter objects to be seen - such as the Orion, the Dumbbell and Crab nebulae, fainter stars in the Hercules cluster, and external galaxies like the Whirlpool. Telescopes also come in a variety of "configurations" to match your interests. So what about choosing a telescope ?
Choosing a telescope
Like binoculars, there are many factors to consider before a purchase. If you join an astronomy group there will be opportunities to look through and use different types of telescope at no cost ! Here is a link to some of the terms used. Amateurs still make their own telescopes, and there are groups who specialise in this activity. Telescopes fall into 5 basic categories:
1) Glass element at the front (Objective): Refractor (Achromat and Apochromat(APO))
2) Glass and mirror (Catadioptric) : Cassegrain, Maksutov, Schmidt Newtonian, Ritchey Chretien
3) Mirrors only: Newtonian reflector.
4) Mirrors with relay lenses: Some short tube Newtonian
( 5) Although 'not a telescope', a modern digital camera with a long or zoom lens can be mounted on driven ('EQ') mount. Often the resulting 'live view' can even be fed to a computer display ! )
Mounts for telescopes
Telescopes are mounted so you can follow ('track') the stars as they move across your field of view. Modern mounts are motorised and most come with controls that allow the user to 'select' the direction in which the telescope is 'aimed' (this is known as a 'goto' function). The two types of mount 'head' are:
1) Alt-azimuth or 'fork' mount = essentially the same as a camera tripod mount
2) Equatorial or 'EQ' mount (aka German or "GEM" mount) = a mount head that is 'tipped up' so it can be aligned with the Earths axis
To follow ('track') the stars, an alt-azimuth mount has to be moved simultaneously in both axis. This is quite difficult to do manually, and whilst it's easy enough with a motorised mount, if you want to take long exposure photos you will need to 'covert' it to EQ operation by fitting a 'wedge' (which can be quite expensive) - otherwise your photo will suffer from 'field rotation' distortion.
The EQ mount (once it has be correctly be aligned with the earths axis), only has to be driven in one axis to track the stars.
All telescope mounts (except the Dobsonian = see later) have some sort of slow motion control that allows you to adjust the tracking. Examples are:
1) Manual tracking only.
2) A simple 'sidereal' drive motor (EQ mounts only need one, Alt-azimuth two)
3) Motors with a hand controller or computer for 'GoTo' operation
'GoTo' operation is now common on even the cheaper mounts and, when the telescope has been properly aligned, allows you to select an object from a menu on the hand controller. The controller them moves the telescope to point at the selected object (hence 'GoTo').
Choosing a telescope is dictated by your needs and circumstance and in what order you place the following criteria :
|very portable||visual||photo||DSO||planets||wide FOV||EQ / GoTo||Alt-Az / GoTo||under £500|
|3-4" refractor goto||Y||Y||Y||Y||Y|
|6" F/5 Newtonian||Y||Y||Y||Y||Y||Y||Y|
|8-10" F/4 Schmidt||Y||Y||Y||Y||Y|
|DSLR+zoom lens on GEM||Y||Y||Y||Y||(can be)|
visual - best for visual observing
photo - suitable for imaging
DSO - suitable for observing Deep Sky Objects (galaxies etc)
planets - suitable for observing the moon & planets, as well as star clusters & bright nebulae
wide FOV - Field Of View exceeding 2-3 degrees
under £500 - good choice for those on a low budget
The eyepiece magnifies the detail in the image formed by the lens or mirror. It's likely you will want to buy additional eyepieces at some point. The magnification is controlled by the focal length of the eyepiece: M = F/f, where M the magnification = is F, the focal length of the telescope, divided by f, the focal length of the eyepiece. For typical telescope focal lengths (1m = 1000mm) the 'most used' eyepiece will be between 20 and 40mm (i.e. magnifications between 50x and 25x). Only with a sturdy mount and good tracking will magnifications above 100x be used
A new telescope will come with at least one eyepiece - typically of 20 or 25mm focal length - or a 'kit' containing a second eyepiece and a 'Barlow' and perhaps some other bits (like a moon filter). Cheaper telescopes will advertise their maximum 'Magnification' - which, of course, depends on the eyepiece - and to back up their outrageous claims the second eyepiece supplied will have focal length of 5mm or so. Cheap designs with such a tiny exit pupil and almost zero eye relief will prove impossible to use in practice (and is a common reason for beginners to become disillusioned with their first telescope)
However modern telescopes all have decent mirrors and there is an extensive range of eyepiece types and suppliers to choose from. They are offered in two draw-tube sizes: 1.25" and 2". Modern telescopes will have a 2" draw-tube and come with a 2"-1.25" step down ring, so can be used with both sizes of eyepiece. Older (second-hand) telescopes may be 1.25" (31.7mm) only. A 2" eyepiece typically has more 'eye relief' and is much easier to see through (i.e. much easier to 'line up' with your pupil). Whilst the focuser and draw tube on older simple Newtonian reflectors can often be upgraded, the 1.25" fitting is adequate in most circumstances, especially for the beginner (who will not want to pay 3 or 4x the price for a 2" eyepiece when the 1.25" equivalent will 'do the job'). Modern eyepiece designs types are:
TYPES: Plossl, Wide Angle, Ultra Wide Angle, Konig, Radian, Panoptic, Nagler.
MAKES: Teleview, Meade, Celestron, and a number of others.
A Barlow is used to increase the focal length of the telescope - typically by x2 - and so increase the magnification of any eyepiece it is used with. This is very useful if you have a few eyepieces and want to extend their magnification range. Barlows are also used to project larger images onto web cams. The results thus obtained imaging the planets and the Moon can be stunning. Whilst the 'normal' Barlow provides x2 magnification (with x2.5 and x3 also being 'common'), at the top end is the Powermate (x5). Of course, this "King of Barlows" also comes at a "King's Ransom" price (although you may get lucky and find one on eBay for less than £250 !)
As well as allowing higher magnification, increasing the focal length also makes the focus 'more forgiving' = however the downside is that the brightness of the image is more than halved (for a x2 Barlow) and thus imaging exposure times are doubled (which makes your 'tracking' even more vital). Any chromatic aberration present is also magnified
Filters can reduce light pollution and enhance contrast on faint objects. They can be used on the Moon to gut down glare, and coloured filters will bring out detail on planet, or reduce colour fringing.
For more on Filters, see our FAQ page
Scale in the sky
Your hand held at arm length is a good way to estimate angles on the sky. The diagram right illustrates how to judge the angle between stars in the Plough (Great Bear, Ursa Major) and hence any other area of the sky. The width of a finger tip is about 1 degree and should cover the Moon completely - try it.
The sky is measured in degrees. A full circle is 360 degrees. From horizon to zenith ( strait up) is 90 degrees. Your binoculars show only a 7 degree portion roughly, but it is useful to know more exactly because it will depend on the magnification you have.
Some scale markers can be found in the sky:
For Moon 0.5 degrees (deg), Andromeda galaxy 1deg, Orion's belt 2.5 deg, Caster to Polux 4.5 deg, the pointer stars in the Great Bear 5.5 deg, the sides of the Great Square of Pegasus 14 to16 deg.
The Solar System to scale
It's very hard to show the Solar System to scale. To fit the whole Solar System into your living room the Sun in the middle would be only 2/3rd mm in size (and Earth would be invisible, at less than 2/10,000 ths of an inch !). If you make the Earth a more visible 1" (25mm) marble, then the Sun is 2.8m (9ft) across, Jupiter a football (12" = 1 foot, about 305mm) and the whole Solar System (the orbit of Neptune) is 7 miles (about 19km) across !
You can download a short (5 minutes) film of a "7 mile scale solar system" being set up in the Nevada desert from one of the links below (or view the whole video on-line at YouTube)
In the '7 mile Solar System', the orbit of Neptune is scaled so it's 3.5 miles from the Sun. On the same scale, the distance from Proxima Centauri (the next nearest Star to the Sun) - itself of scale size about 1.2m exercise ball - would be about 31,000 miles, just short of 4 times the diameter of the Earth (about 8,000 miles) i.e. about 1/8th the distance to the Moon ...
Due to MAS site security restrictions, the following movies are unlikely to play in your browser. Right click and 'save link as' instead - HD720 (.mp4) version - DVD (.mpg) version
To build your own 'Scale Solar System', you can use an on-line tool to calculate the sizes
Identifying what you see
Sweeping the sky with binoculars on a warm August night is probably one of the delights of owning a pair of binoculars or a wide field low power telescope. How would you identify a misty blob or cluster ?
Well you really need to know the basic star patterns in relation to a map, and the only way to do this is take an atlas with you and a red torch to read it by. (Red light does not effect dark adaptation). First keep your head pointing in the same direction of the object but lower the binoculars so that you can see the whole area of sky. Raise the binoculars again to confirm the location of the object. Go to the star atlas and identify the area and the object or sketch the star pattern in a log book.
Of course the Google Sky Map app., running on a Tablet or 'smart phone', can also help you identify whats in the night sky :-)
Stars maps and log books
A planisphere (eg Philips) enables you 'dial in' the exact view of the sky and shows all the constellations above your horizon and their direction. You can even make your own planisphere (if the link doesn't work, the two PDF layout files are copied here: bottom part, and top part.
For binocular users, a book devoted to the subject with star maps would be recommended. There are other options e.g. Norton's Star Atlas, Collins wild guide "Night Sky" and many others.
The Google Sky Map app. for tablets and smart phones users will 'paint' the constellations over a star map of the sky in the direction you are holding the tablet etc. NB. all 'direction sensing' apps. use the built in compass - this is easily 'fooled' by the stupid magnetic clasps found on many fancy expensive 'up market' leather tablet cases (iPad users please note) :-)
A log book records important information which you might otherwise forget: Date, Time, Location, Instrument, field of view, direction in the sky, description, weather conditions.
For those who no longer use paper and pen, the Night Sky Tools app. for android tablets and smart phones not only has extensive lists of 'whats in the sky tonight' but also has an 'Observation Log' option that allows you to enter details 'in the field'
Estimating star brightness
How bright was it? I asked, "As bright as the Moon" was the answer. That was the description of a Leonid meteor which exploded on the night of November 16/17 1998. A meteor brighter or as bright as Venus is called a "fireball" and much brighter events could be described as a "bolide". The SPA describes these terms here. Apart from the Sun and Moon, the planets Venus, Jupiter and Mars rank as the brightest objects - oh and of course the occasional "Great Comet" such as West (1976) Hale-Bopp (1997) and 2006P1 McNaught (2007) which was recently judged "as bright as Jupiter".
The magnitude scale
At the other end of the scale are stars that are just visible to the naked eye. Hipparchus in 120 BC put the brightness of stars into six groups, 1 to 6. (One being the brightest). However the notion of "1st magnitude stars" also includes stars like Sirius, which on the modern scale (Pogson) is magnitude -1.5. But this star is exceptional and all the brightest stars fall into the range -0.7 to +1.6. So including Venus the naked eye range of brightness is -4 to +6. In practical terms it useful to remember that a difference of 5 magnitudes is a difference of 100 in brightness, and that one magnitude is a 2.5 x difference. When estimating the brightness of objects, it usual to compare with a nearby star, and then go and find out the magnitude of the star from a chart, book, or sky software. For more on Star Brightness, see the FAQ page
Time in space (UTC)
All times for astronomical events are given in UTC = "Universal Coordinated Time".
Note. If the time in the UTC box above is not automatically updating each second, it's because you have Java-Script 'turned off'. If you don't want to enable Java-Script for this page, 'Refresh' the page instead
To within a second or so, UTC is the same as GMT - to convert from UTC to UK 'local time', all we have to do is ADD AN HOUR during the summer (for British Summer Time).
To discover the times of some future events, check out Time & Date.com
FAQ page topics from members
The FAQ page has a list of common topics, frequently asked questions and 'hints & tips' gathered from members over the years. Much of the material has been taken from topics presented at our past meetings and the collection covers most of the more common Questions that people ask when first starting out in Astronomy
(Note - you need to use the eMail address you 'registered' when you joined as a Member before the maidenhead-astro mail server will accept mail from you = this is the only way to prevent us drowning in spam)