Your eyes are amazing instruments. If you allow them to adapt to the night sky they will be able to see very dim and distant objects. However, two limiting factors of using your eyes are that you cannot ‘zoom in’ and, once your pupils are at their maximum, you can’t increase the amount of light entering your eye. A camera, however, can do both! Even a modest mobile phone with a built- in camera can zoom in and collect light over a long period and display all of that light in one go with some adjustment and a steady hand. Of course, this means you can see more detail and fainter objects. For example, many people successfully use their mobile phone to take stunning pictures of the Moon. However, if you have a telescope you can put the mobile camera over the eyepiece, turn off the flash, zoom in (no more than x2), touch the screen where the moon is (it will bring up a box), slide the exposure to prevent a blurry image. You’ll need to be steady! You may get lucky and produce an amazing image.
To increase the chances of a better picture you need a tripod or ‘mount’. The latter can be set up so that it moves ever so slightly as the earth turns, in effect stopping stars from appearing to drift (and blur). Although letting the night sky arc across the sky makes a great picture.
With this set up you can open the shutter on your camera for ages, letting in bucket loads of light to display in a single image.
A camera has another trick up its sleeve. It can pick up types of light that your eyes can’t. A camera can pick up wavelengths of light such as infrared beyond your biological limits. (Just for the record, snakes can see infrared light and bees can see ultraviolet light!) Many astronomers tinker with their cameras to remove internal filters that block a lot of light and this makes a huge difference to the light that can be collected in a short time. However, in most cases, after that modification you can’t use the camera for taking ‘normal’ pictures.
If you are lucky enough to travel to a place where the northern lights are visible, here are some useful tips. Get and use a tripod. Without it, you will struggle. In the daylight focus on a very distant object and then turn AUTOFOCUS OFF. For the best results this next bit is technical. You need to get a lot of light into your camera so set the aperture at f/4. Secondly, set the ISO to 800. Finally, set the exposure (how long the shutter is open) to between 5-25 seconds, so experiment. It is best that you use a delayed timer if possible or, better still, a cable release so that you don’t end up shaking the camera as you press the button for your amazing shots!
Don’t forget to put autofocus back on after your session.
Between April 21-22 the annual Lyrids meteor shower arrives just before the New Moon on 23rd. If the weather is clear, we should have a good display of about 18 meteors per hour. Although this is not a huge number they are fast and therefore packed with energy as these particles hit the atmosphere and leave persistent trails. Look NE half way up in the sky late/early morning and they will appear to radiate from this point across the sky.
Planets this month.
Venus passes the Pleiades, a cluster of stars (also known as The Seven Sisters) in the evening between 2-4 April. To catch Mars, Saturn and Jupiter get up early between 15-16 April to get a good view of all 3 low in the SW.
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