July Sky Notes

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.

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.

Of course, you can also do all of this with the aid of your local, friendly astronomer or astronomical society.

Sky Notes

Please note all times given in this article are in BST so remember to add an hour to get the time in BST which started on Sunday 30th March.

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 30th March.

Sun: The Sun is never very far below the horizon at night until the latter half of July, so it never gets astronomically dark, and this is not the best time for the observation of faint objects. If you are able to safely observe the Sun, there are plenty of sunspots to be seen as our star is now at the peak of its cycle of activity.

Mercury and Venus:  Both of these inner planets are closer to the Sun than the Earth so are never very far from the Sun (especially Mercury).  The innermost planet is not visible this month, being lost in the bright twilight. Venus rises as the Morning Star at about 2am.

Mars:  The red planet can be seen low in the south-west shortly after sunset against the background stars of Leo. At this time it is very faint as the distance between Mars and the Earth increases. The red planet sets at about 11pm. 

Jupiter:  Jupiter begins the month behind the Sun, from our point of view but in the second half of the month reappears as a morning object visible from about 3.30am.

Saturn: The ringed planet rises a little before midnight and can be seen against the background stars of Pisces.

Uranus and Neptune: Uranus is visible from about 1.30 am against the background stars of Taurus and just below the Pleiades star cluster. Just visible to the naked eye, the planet can be seen in binoculars or a small telescope. Look for a tiny, distinctly greenish disc. Neptune rises around the same time as Saturn and is very close to the ringed planet, which could be used as a guide to the more elusive Neptune. Its blue disc can still be seen in good binoculars or a small telescope against the background stars of Pisces. 

Pluto: The former planet Pluto reaches opposition (opposite the Sun in the sky) on July 25th. Whilst this coincides with its greatest altitude above the ecliptic it will still be too low for observers in Torquay to view easily.

Meteor Shower: The Delta Aquarid meteor shower peaks on 29 this month. This is not a very active shower but around 16 meteors an hour can be expected. The Alpha Capricornid shower is active for most of the month but the radiant never rises very high in our skies so only a small number of meteors are usually seen.

Noctilucent Clouds:  It may seem anachronistic for astronomers to be interested in clouds, but these rare apparitions are best seen at this time of year.  Noctilucent clouds are so high (over 80 km) in the atmosphere that they are able to reflect sunlight even when the Sun is well below the horizon.  The tiny ice crystals that make up the clouds reflect bluish-white light that stands out against the gloaming sky.  They are typically seen 1 ½ to 2 hours after sunset low in the Northwest or before sunrise low in the Northeast.

Moon: The First Quarter Moon occurs on July 2nd with Full Moon on July 10th.  Third Quarter then follows on 18th with New Moon on July 24th.