Solar Eclipse Observing Tips

On the morning of Friday 20th March 2015, the Moon will pass in front of the Sun, blocking the Sun for a brief time and causing all of the British Isles to enter a period of twilight around 9:30am!

Solar-eclipse-2015-vDepending on your location in the UK, the Moon will begin to pass in front of the Sun at 08:22UT in Southampton and around 08:36UT in the far north of Scotland.

Unfortunately, for us the the UK, this will not be a total solar eclipse, and as with any observation of the Sun, special precautions need to be taken in order to observe the Sun safely. In the Faroe Islands, there will be a total solar eclipse, so if you are planning a holiday there, you may just see the eclipse, weather permitting.

As you can see from the gif above, the totality track is the black spot that crosses from the SW to the NE but the area where the partial eclipse is visible is much larger. The closer to the black spot you can be, the greater the Sun will be eclipsed.

What will it look like?

A video showing the night before and morning of the eclipse.
2015_03_05_20_22_17.mp4

A closeup of the Sun and Moon.
2015_03_05_20_15_03.mp4

There are lots of opportunities to observe the eclipse, and this will be the last eclipse in the UK for a decade.

Safe Solar Observing

A number of strict rules should always be adhered to when observing the Sun.

  • When using a solar filter, always place the filter on the sun facing end of the telescope as the focused Sun will melt filters at the eyepiece end in a matter of seconds.
  • If stopping down a large aperture telescope, make sure that the stopped down area is not receiving any stray light and blocks the Sun completely.
  • Make sure that the filter cannot be blown off by gusts of wind – use some masking tape to secure the filter in place.
  • Never leave a telescope pointing at the Sun unattended.
  • Always check the solar filter is in place before you look through the eyepiece.
  • Never look at the Sun through an unfiltered telescope using eclipse shades or a welder’s filter. And don’t use a camera with a telephoto lens, even if the lens has photographic filters on it that appear to darken the Sun.
  • Filters that are not safe, though they are sometimes recommended in old books, include smoked glass, stacked sunglasses, crossed polarizing filters, and neutral-density camera filters. While these may greatly dim the Sun’s glare, invisible radiation may get through and damage your eyes.

(Extract from the NIAAS website)

Where can I observe the eclipse?

Anywhere in the UK, but if you are looking to observe the eclipse along with thousands of others, local astronomy clubs will have observing locations throughout the UK and Ireland.

To find a local astronomy club in your area, please check out the links below.

http://fedastro.org.uk/fas/members/
http://www.irishastronomy.org/index.php?option=com_weblinks&view=category&id=28&Itemid=14

What way can I observe the Sun safely?

There are a number of safe ways to look at the Sun, including:

  • solar glasses
  • a telescope
  • binoculars
  • monocular

Be aware that looking at the Sun can cause permanent blindness and needs care and attention to do safely. Children should be supervised by adults at all times.

Solar Projection

You can project the image of the Sun using a refractor telescope, one side of a pair of binoculars or a monocular. NEVER LOOK AT THE SUN DIRECTLY THROUGH AN UNFILTERED TELESCOPE, LENS or CAMERA.

To project the image of the Sun safely, set up your refractor telescope with eyepiece or binoculars on a tripod in a clear level location. Observe the shadow that the circular shape of the instrument makes on the ground and point the telescope in the direction of the Sun. Using a white piece of card, hold the card in front of the eyepiece and use the focus ring to achieve a sharp image. Start off with a wide angle eyepiece, e.g. 40mm. before zoning in with a higher magnification.

solar_projection
Photo by Giles Campbell-Wright, Australia

If you want to use a pair of binoculars, it is best to cover one of the lenses.

Solar-eclipse-Baja-projection-method
Projecting with a pair of binoculars on a tripod. Courtesy of Universe Today

You can even use a pinpoint of light to project an image like a pinhole camera. In this example, a colander has been used to project hundreds of suns :-)

From Imgur
From Imgur

 Solar Filters

There are a number of different types ranging from a few pounds to over one hundred pounds depending on the type you want.

For most people, a pair of solar glasses will be the best way to observe the eclipse. These are safe and easy to use with children and available on Amazon.

For those with a telescope, you can make a relatively cheap solar filter using Baader Solar Film which comes in an A4 sheet which you then have to cut and glue onto a homemade lens cap. Instructions here. You should ALWAYS place the solar filter securely in front of the telescope, never at the eyepiece.

If you don’t have time to make a filter, you can purchase one made of solar film below.

eBay seller selling solar filters to fit most lens caps
eBay seller selling solar filters to fit most lens caps

Or for something a bit better quality, have a look for “Thousand Oaks” solar filters which are glass solar filters specially designed for telescope observing and photography.

If you are using a digital SLR, you can buy a Neutral Density filter, ND-100,000 which is specialised for solar photography. Do not be tempted to buy ND-1000 and build them up as the heat generated could be catastrophic.

Or, for a cheaper option for digital SLRs, you can buy a Cokin filter adapter and some Baader Solar Film and glue the film onto the flat surface of the Cokin adapter.

 

Understanding more about the Sun

For more information about the Sun and the features you can observe, please check out John McConnell’s (Fellow of the Royal Astronomical Society) excellent guides below, and follow him on Flickr. (with a few of my own sunspot photos included).

solar observing
Solar Observing Tips
Solar Features
Solar Features