3 December 2014

Binocular stargazing

Taking a closer look at the stars

[Warning: NEVER, EVER look at the sun directly, either with Binoculars or without. Doing so can cause permenant blindness!]



One thing about looking at the constellations is that you can already see many of them with your eyes. Certainly, for the brightest northern constellations, like Orion, Taurus, Gemini, or asterisms such as the Big Dipper (part of Ursa Major)...you can easily see them on a clear night. Even in the city you can see many of the brightest stars, but it's not that many compared to how many are visible in good darkness.

But once you start looking, and finding out more about the constellations and objects you're studying at the time, you might realise you'd like to better see if, for example, you can actually see a particular binary as two separate stars (ie you can 'resolve' them). Or perhaps you can see Orion's Nebula, where it is, but you know there are other features you'd like to see a little clearer...for instance the Trapezium - four bright stars in the centre of Orion's Nebula. And there are some stars and constellations that just aren't very clear at all without a little help for your eyes.

The first thing you might think you need is a telescope. It's what you associate with stars and stargazing. But, actually, to start with at least, what may actually be better for you is a pair of binoculars!


Binocular stargazing and bird watching



The great thing about stargazing is that you can pick the level you'd like to take it. For someone just learning about the constellations and where they are, learning how to use a telescope might not be the ideal thing. The good thing is that you don't need to. Many people have binoculars hanging around the house...maybe for bird watching, or taking to the races, or simply looking at boats out at sea... try those first!

Binoculars or telescope?

  • You might already have some, or can borrow some from a friend or neighbour (or, if you really want to buy, they tend to be much cheaper than telescopes.
  • They are easy to carry around, light.
  • They are quick to take out and put away - you don't have to set them up (unless you go for a larger/heavier pair that needs a tripod/mount)
  • You might be used to using them, and it feels more natural to look through two eyes than squint through one.
  • It is easier to find the celestial object you're looking for with two eyes than one
  • With two eyes, you can check out a larger field of view and be sure where you're looking.
  • What you see is the right way up and the right way round. You don't have to re-learn where everything is upside down (or sometimes back-to-front) as you would with a telescope.
  • Even professional astronomers keep a pair of binoculars to hand to help them spot something fast (especially good for meteor-watching).
  • Depending on the magnification and 'field of view', you can spot many of the main nebulas and celestial objects...it's a good starting point to taking observations up a notch.


Checking out your binoculars for stargazing





If you are going to buy binoculars for your nightly jaunts to get lost in the stars, you probably won't need more than a basic pair. Most are labelled with two numbers with a 'multiply' or 'x' in between eg '7 x 35'


Magnification (or power)


The first of the two numbers is simply the magnification. How much bigger is it than without? So, in the example of '7 x 35' the '7' means what you can see through the binoculars looks 7 times bigger (It's magnified by 7 times). To start with, it isn't necessary to have a higher magnification than this...you'll see a whole lot more than without!


Diameter of big end lens = aperture

The second of the two numbers (in this example '35') basically tells you how big the large end of your binoculars are in mm. My example here would be 35 mm...a perfect size for a child or someone who can't hold too big a weight. If you haven't already got binoculars, a good size would be about '50' for this number, as that will give you a wider field of view, but not be so heavy they are difficult to hold up and look in the sky.
Many an enthusiastic person thinking they want as big as number as possible has ended up with arms aching so much from holding the  binoculars up that they've had to give up that night, or then go out and buy a stand (mount) for them! If you're looking for hours, then you have to find a middle-road between the 'best possible' and the practical aspects of actually holding something in the air for a long time.

Buying binoculars for stargazing

If you haven't got binoculars you can beg or borrow already, then a good article to read about what to look for, and how to choose one, can be found in Sky &Telescope. I was pleased to see the writer, Ed Ting, held the same view as myself, that lower power binoculars are not only adequate, but often desirable, not only for how heavy they are, but also because, beyond a certain point (eg magnification of 8 to 10) it becomes a lot harder to see any difference in the quality of your view! He also shows some good pics of the parts of the binoculars and how they work.
EarthSky recommend this YouTube video to assist you buying binoculars:(https://www.youtube.com/watch?v=PN4KFT-QLck)

Best Books on Binocular Stargazing

There are quite a few astronomy books available for naked-eye and binocular stargazing. Here are a few I picked off the shelf at Amazon. If I were choosing a book though, I would probably go to my local bookstore and at least flick through a few first - what might suit one person might not suit another. Each person likes different things. Some like more and bigger pictures, others like lots of description of what they might find. You could always go online afterwards and see if you could get a better deal:

Equipment to take Stargazing

  • The thing about books on astronomy is that you tend to have to study them before you go out. However, if you do intend to take one out with you, make sure your torch has a red light*! [For good uninterrupted viewing, I have one of those little keyring LED lights with a red plastic sweet wrapper (such as are sometimes wrapped around certain boxed chocolates) and kept on by an elastic band.]

*This is because, every time you look at a white light, it fires up the colour sensitive 'cone' cells on the retina, especially in the site of the fovea at centre of the eye. So, afterwards, when you turn your torch back off and look up into the sky, you'll find you've lost your night vision and can't see as many stars. Then it takes about 10 to 15 minutes to allow the  more sensitive 'rod' cells to kick in and give you back your night vision again

  • Anything you need to keep warm eg. coat, hat, gloves, scarf and a darn good blanket if you're sitting or lying down! Because you're so still, you can get cold pretty quickly, and end up going home shivering and fed up.
  • Anything you need for comfort. If you're going to be out for a matter of hours, you can use a reclining chair (foldable for portability) and/or a blanket. You might think it unnecessary to take a chair andblanket, but depending on the chair, sometimes sitting on a warm blanket can keep your bum warm and reduce discomfort. Without a chair, remember that if you're lying back on a blanket, it can become quite damp with dew at night. I've found, for the ground, a plastic-backed picnic blanket is best.
  • If you're out half the night watching meteor-showers, why not take a light flask of your favourite hot drink, and a snack. Having a picnic under the stars is fun :-) 
  • Consider, also, a phone/ipad with your favourite stargazing app on (again, make sure it's an app that has a red back-light, so it doesn't blind you every time you use it). Taking an electronic device is absolutely not necessary...but there are some that you can hold up to the sky and it tells you exactly what you're looking at...maybe useful for an absolute beginner.

Recommended Night-sky Guide

For what's good to look at tonight in the Northern hemisphere a good page is EarthSky Tonight, and another is Meteor Watch.
These pages tells you if the planets are crossing any stars or other celestial objects, and other fun things to look out for.


Happy Stargazing!



2 comments:

Anonymous said...

What are the pros of buying a telescope rather than a pair of binoculars? Would be good to hear both sides!

Annelisa Christensen said...

Hi, and thank you for your suggestion.

There are certainly pros for a telescope, and I can talk about this in another post, but what I was suggesting was that, for an absolute beginner, taking stargazing up a notch from simply looking up at the sky without any instruments, a pair of binoculars is often considered better (for the reasons I've given in this post).

Before spending a big chunk of money on a telescope, it's a good idea to get a feel for stargazing and then go on to a telescope. But even then, many a professional stargazer will also keep a pair of binoculars by their side for fast focusing on some celestial object/event!