August Sky Notes

However, there are ways to view our star safely.

The simplest, and perhaps the cheapest way is to use a device variously known as a solar viewer, eclipse viewer or eclipse glasses.  These items are usually available from reputable telescope traders or from organizations like the British Astronomical Society and your local society. Check that there are no scratches or pinholes in the film “lenses” then you can safely use these to observe the Sun providing you follow the instructions usually printed on them. The largest sunspots which are typically many times the size of the Earth can be seen with these devices. WARNING: The traditional piece of smoked glass or X-ray film does not produce a dense enough filter to protect your eyes, so do not use them.

The traditional safe method of viewing sunspots and solar activity is by projection. Even a small bird-spotting telescope will show a solar disc of several centimetres in diameter. The telescope should be set up by looking at the shadow of the ‘scope and making it as small as possible. DO NOT PUT YOUR EYE TO THE EYEPIECE. Use a piece of card as a screen on which to project the disc of the Sun. Move the card in and out to focus the image. A variation of this method is to mount the card screen in a box and move the box forward and back to focus. This method has the advantage that the box creates its own shaded screen. It is also possible to project an image using binoculars. First create a hinged card (I used the front and back covers of a loose-leaf writing pad. Make a hole in the card side just large enough to take one eyepiece of the binoculars (most good binoculars have one eyepiece that will extend a little further than the other) Then remove just one of the lens caps and focus the image by tilting the hinge up and down. Both of these methods will reveal many sunspots depending on how well you can focus the image. BEWARE: glass at the eyepiece end of binoculars or a telescope will heat up and can shatter, so it is best not to observe continuously but to use an “off and on” method to prevent excess heating. Projection of a small disc can also be achieved by using a home-made pinhole camera. Use any sort of box and cut an aperture at one end then cover it with paper to create a screen. Then make a small pinhole in the other end of the box. Point the pinhole at the Sun and observe the image on the screen. It can be a bit fiddly lining the hole up with the Sun so that the image falls on the screen, but do not give up and you will be rewarded with a safe view.

If you already have a telescope and are happy to spend a bit of money on a filter, there are some guidelines. Always use an “objective filter” NOT an eyepiece filter, which is often what manufacturers of cheap telescopes include in the kit. These are just as prone to heating and shattering as any other eyepiece. An objective filter looks like you have inverted a tin can over the end of the telescope and you will not be able to see anything through it at all unless you have the Sun in view. These filters work by cutting out 99.9% of all the light to make them safe to view through. The resulting image can, sometimes confusingly, produce an image which is either white, yellow, orange or blue, depending on the material used in making the filter and which wavelength of light it is biased towards.

If money is no object, specific solar telescopes can be bought. These look like very small telescopes, typically just 1” in diameter. A view of the Sun and sunspots can be gained using these devices. They have the advantage of having a dial which alters the wavelength viewed so that you can tune the coronal flares and prominences in to view. Being so small does make them light and tricky to handle in any wind and some people find them difficult to look through. These days, amateur astronomers are also able to produce the spectrum of the Sun and stars. By doing this the composition of the stars in view can be studied.

A few hours after “chasing the dragon away” we should be treated to a very prominent “rain of fireballs”, however these two events taken together do not constitute the “end of the world”.

There are times when we look into the night sky and see bright trails of light, lasting just a few seconds. These are caused by the burning up, due to friction, of small particles that orbit the Sun in the wake of comets and are swept up by the Earth’s atmosphere as it intersects that orbit.  August sees the brightest and often, most spectacular, of the annual meteor showers; the Perseids – so called because they appear to radiate from a point in the constellation of Perseus.  Because the eclipse has occurred, we know that the Moon is “New” and will not appear in the sky to drown out the shooting stars. This means that this year the sky will be as dark as possible and the shower should be seen at its best. The maximum of activity takes place on the night of 12th/13th when up to 60 meteors an hour may be seen.  This figure is standardized by assuming the radiant point will be directly overhead so that meteors travelling in all directions can be seen. However in actuality the radiant is relatively low in the North-Eastern sky until the early hours of the morning, and this is the best time for observation, although it is worth looking out from the moment it gets dark, after 22.30.

Observing meteors could not be simpler.  The only necessary bit of equipment is a garden recliner or deck chair so that you can lay back and look at the sky about 40 degrees above the horizon comfortably.  If you want to make a record, simply count the number of meteors you see.  You can also note the direction of travel, the duration, which will typically be seconds, and anything unusual such as colour, faint trails, or sound.  This shower is known for producing occasional, bright fireballs.  A fireball is defined as a meteor bright enough to cast a shadow.

Please also be aware that, even in August, it gets cold towards midnight so bring extra layers to wrap up in. It is also a good idea to bring a warm flask of drink and snacks to help keep you alert.

The Torbay Astronomical Society will be holding a group meteor watch at the Torquay Boys’ Grammar School Observatory site in Shiphay Manor Drive from 10pm. Members of the public are welcome to join us.

To further accentuate the “end of the world” feeling there is also a Partial Lunar Eclipse in the early hours of August 28thwith the maximum eclipse at 04.30 GMT. The Moon enters the shadow of the Earth and dims. It often changes to a russet colour which is why it is also known as a “Blood Moon”.

Sky Notes

Sky Schedule

Please note all times given in this article are in GMT so remember to add an hour to get the time in BST which started on Sunday 29th March.

Sun: Astronomical darkness increases to 6 hours by the end of the month, so fainter objects are again becoming observable. August 12th sees the Partial Solar Eclipse. (See main article)

Mercury and Venus:  Mercury is not visible this month as it lies too close to the Sun to be seen. Venus lies close to the Western horizon but should be visible as it is so bright. It may be possible to catch a glimpse of Venus during the Partial Solar Eclipse on 12th.

Mars:  The red planet lies in the constellation of Gemini, visible in the morning sky, rising at about 2am.

Jupiter:  Jupiter is not visible this month as it rises at about the same time as the Sun.

Saturn: The ringed planet can be found against the stars of Pisces, rising almost due East around 22:00 and then visible for the rest of the night, The rings are beginning to open out, from our point of view and are consequently becoming brighter and easier to see.  Saturn’s largest moon, Titan, can also be seen with a good pair of binoculars or a small telescope.

Uranus and Neptune: Uranus rises soon after midnight and is seen against the background stars of Taurus.  At magnitude 5.8 it is visible in binoculars.  Look for a tiny greenish disc compared to the pinpoints which are the stars.  Neptune is seen against the background stars of Pisces (below the asterism known as the Square of Pegasus).  It rises at about the same time as Saturn and is only a short distance away from the ringed planet. At magnitude 7.7 it will require large binoculars or a small telescope to find it.  Neptune displays a smaller and truly blue disc compared to that of Uranus.

Meteor Shower:  The Perseid meteor shower peaks on 11th-12th this month.  This is the best shower of the year with up to 60 meteors an hour although this could rise to over 100/hour in dark skies and may include some very bright ones. (See main article).

Moon: The Third Quarter Moon occurs on August 6th  with New Moon on August 12th. coinciding with the Partial Eclipse of the Sun. First Quarter follows on 20th with Full Moon on August 28th , coinciding with the Partial Eclipse of the Moon.