Venus in Daylight

On Tuesday afternoon I was checking out the half-metre telescope at Nottingham Trent University and wanted to confirm that it was pointing correctly. Venus is well away from the Sun so using The Sky 6 software I slewed the telescope to Venus which duly appeared in the finder and main telescope eyepiece.

The last time I looked for Venus during the daytime was on La Palma many years ago. Two dutch astronomers were using the 1-metre Jacobus Kapteyn Telescope (JKT) to look for ice crystals in the venusian atmosphere. If there was ice present then sunlight would be refracted in the same way it creates a halo in the Earth's atmosphere. When the angle between the Earth, Venus and Sun was just right then this refracted light would be detectable.

Using the telescope tube as a guide I looked for Venus with my naked eye. It took a while to see it but once I latched onto it I wondered why I hadn't been able to see it sooner as it was very bright and obvious. I looked away then tried to find it again, only to discover that it was just as difficult as the first time.

My theory is that in a clear blue sky it is difficult to persuade your eyes to focus at infinity if there is nothing to latch onto. Once an object is found then focus can be maintained and the object remains obvious. John thinks it may also be due to our eyes scanning quickly when looking at a blank sky.

Back at Green Witch on Wednesday I looked for Venus again. There was a bit of high haze but I felt it worthwhile. I couldn't find it with my naked eye or with binoculars even though I had a reasonable idea of where it ought to be. Lee suggested trying the Celestron Nexstar 6 SE. We could line it up on the Sun as a reference then do a 'go to' Venus. We didn't have a suitable solar filter to hand so aligned approximately on the Sun by projecting an image onto Lee's hand.

After slewing to Venus Lee carried out a small search to locate it. Notice the shadow which gives an indication of how far Venus is from the Sun.

Focusing the telescope was done on a vapour trail left by a jet climbing away from Stansted. When we sent the telescope to Venus there was nothing in the eyepiece but a very short search around the location quickly found Venus. Considering how approximately we had aligned the telescope we thought the pointing performance was very good.

Having 'synced' the Nexstar to Venus it tracked it well for the next couple of hours and we took a few photos with a digital camera held up to the eyepiece. Venus is about 42 degrees away from the Sun (about two hand-spans) so why not try finding it for yourself on the next sunny day? I would be interested to hear if you can see it with your naked eye but please be careful of the Sun, especially if you use it as a reference to align your telescope or if you're scanning the sky with binoculars.

This is the view taken by holding a Leica D-Lux 2 camera to the eyepiece. Venus is the bright dot. Inset is Venus zoomed in showing its distinct phase.

Other uses for the Nexstar Mount

One of the nice features of Celestron's Nexstar SE series is the ability to remove the tube and replace it with a small refractor such as the William Optics ZS66 Petzval. The ZS66 dovetail fits directly onto the Nexstar mount, or can be used on a conventional tripod making it an ideal scope to use on the sky or terrestrially. And the aperture is large enough to take impressive wide-angle, deep-sky images.

We are offering a special package based around the ZS66 Petzval Telescope which includes a two-speed focuser, hard case, image erector and 3x zoom eyepiece for only 299 pounds. Whether you want to use it on an ordinary tripod, on the Nexstar mount, or both, this represents excellent value for money.

Orreries

An orrery is a working model of the solar system, and usually includes those planets that are readily visible to the naked eye. The first one was made by George Graham in 1710 for the 4th Earl of Orrery, hence the name. We've just taken delivery of a beautifully hand crafted orrery made by Roy Mallet. It is based on designs by James Ferguson (circa 1763) and represents all the planets out to Saturn. Made from solid brass and stained american white oak it is a delight to look at and illustrates many features of planetary and lunar motion.

Its silent internal motor runs the orrery through a year's cycle in 5 minutes; alternatively, a handle can be used to speed up the motion for demonstration purposes. If you get chance we recommend you call in to see it for yourself.

Further details can be found in our online catalogue under Orreries

Looking South at 10 pm

In the last newsletter I described Derek Rowley's approach to presenting the monthly night sky by concentrating on what can be seen in the south. I thought I would do something similar and include a few notes on what can be seen in the south at 10 pm.

Arcturus is almost due south and can be located by following the arc of the Plough's handle. The handle is right overhead and pointing south. Follow the 'arc to Arcturus'. Continuing to follow the same gentle curve a similar distance leads to another bright star, Spica in Virgo. Spica means 'ear of grain' and is usually taken to mean wheat.

It is thought that Hipparchus discovered the precession of the equinoxes from observations of Spica. A temple at Thebes was aligned with reference to Spica when it was built in 3200 BC. Hipparchus lived between 190 and 120 BC by which time the precession of the equinoxes would have made a significant difference to the alignment of Spica and the temple.

Arcturus is in the kite-shaped constellation of Bootes, usually referred to as the herdsman, although many legends surround him and he's sometimes referred to as a huntsman.

Spica is in the zodiacal constellation of Virgo which is rich in galaxies and is thus a popular hunting ground for galaxy researchers. The Virgo Cluster is about 70 million light years away so the galaxies are faint but many can be seen in a medium-sized telescope. Around eleven of them are Messier objects, including the Sombrero, so can be seen with quite modest telescopes.

Heads up on MySky

Meade's new 'point and shoot' guide to the night sky is due to arrive here in July and looks set to be a real winner. Aim it at the object of interest and it will tell you what it is and show you an image of it. It also contains audio and video guides to help you find your way around. Not only that, if you connect it to your Meade goto telescope it will command the autostar to point the telescope at it. Meade say it is like having your own private astronomer standing next to you. And all for only 299 pounds.

For full details please visit the Meade web site . To be sure of getting one of the first to arrive in the UK place an order with us with a 10% deposit.

And finally...

Astroblast 2007 was a great success and  seemed to be enjoyed by all who attended. Iain Nicolson's book signing was very popular and we have a few signed copies of his book 'The Dark Side of the Universe' available at the normal cover price on a first come, first served basis. If you attended Astroblast we would like to hear your views and ideas so that we can continue to improve it. My report is still being written and will be posted soon; in the meantime you can see pictures on the Astroblast web site .

Best wishes and Clear Skies

Neil
www.green-witch.com
www.arizonaskyvillage.co.uk
www.astroblast.org.uk