Constellation in Focus: The Great Bear, Ursa Major
Rather than look at a whole constellation this month, we are looking at the most useful part of the Great Bear - the Plough. These seven stars are recognisable to nearly everyone who has looked at the night sky, and the rightmost two stars are useful for navigation as they point to the North Star, Polaris.
Simply draw an imaginary line ‘up/right’ from these stars and the next bright one you come to is the North Star, although it is dimmer than the stars in the Plough. The angle between the horizon and the North Star gives us the degree of latitude north from the equator; in Rugby this is around 52 degrees.
The two stars that make up the other part of the blade of the Plough are also useful pointers. If an imaginary line is drawn ‘down/left’ and followed you will find last month’s featured constellation, Leo.
If you look at the middle star in the ‘handle’ of the Plough, and with a few minutes to let your eyes adapt to the dark, you will see that it is actually two stars. In a pair of small binoculars it is easy to distinguish Mizar, the brighter of the two, from its companion Alcor
With a telescope of four inches or above and a magnification of around 75 times it is possible to see that Mizar is a double star. Mizar and Alcor form an ‘optical double’ meaning that the stars appear to be near each other in the same way that you can hold your finger up next to a church steeple on the horizon to make them appear close together. Mizar and its smaller companion are a ‘binary’ star, meaning they are actually in the same part of space, just like the Earth and moon.
[Mizar Photo & Mizar-Alcor Photo] – photos taken by David Morris, R&DAS Secretary
If you’d like to learn more about what’s in the night sky and view some of these stunning objects through larger telescopes please feel free to join R&DAS for any of our meetings or enrol on an adult education course (see the Astronomy Events section).
This Month’s Planets
Venus has been extremely prominent in the west after sunset since the beginning of the year but has been slowly getting fainter and spending less time in the sky after sunset since May. However, Venus will take centre stage when it transits the Sun at dawn on the 6th June (see the Transit of Venus section in this report) before becoming a morning object rising in the east just before the Sun.
To locate Jupiter during June you’ll need to be an early riser as its low in the east just before sunrise, but if you do make the effort to get up, do so on the June 17th or 18th, to view a stunning alignment between Jupiter, Venus and the Moon.
Mars and Saturn are in much more favourable positions high in the south all night within the constellations of Leo and Virgo respectively. Though their visibility will be affected by the full moon at the beginning of the month by mid-month they have the sky to themselves as they slowly move towards one another.
Transit of Venus
On June 6th a transit of Venus will be observed from the UK when the planet will pass directly between the Sun and the Earth. When viewed safely Venus will appear as a dark disk moving left to right across the upper half of the very bright solar disk, and with a diameter of approximately 7,500 miles, 114 Venus sized circles could fit across the full width of the Sun. The perfect round disk of the planet will appear very different to the odd shapes of sunspots as can been seen in the above image of the Mercury transit from May 7th 2003 where the small planet Mercury (left) can be compared to a sunspot (right).
Though the transit will be in progress at sunrise (4:45 am BST) from the UK and we can only observe the last 65 minutes of this 6 hour event this is a once in a lifetime opportunity as the next transit will not occur until 2117 and even this won’t be visible from the UK. The next transit visible from the UK won’t occur until 2125!
Of course any observations of the Sun should be carried out very carefully. NEVER LOOK DIRECTLY AT THE SUN WITH THE UNPROTECTED EYE – THIS CAN CAUSE BLINDNESS WITHIN SECONDS. However, don’t let the requisite warnings scare you away from witnessing this rare spectacle. You can experience the transit of Venus safely, and here are a few options:
Get help from the experts: Please feel free to join Rugby & District Astronomical Society at Anita’s Caravan Park, Mollington, Oxfordshire (www.anitascaravanandcottages.co.uk) for our star party starting on 5th June with some night sky observations before an early rise to observe the transit the following morning. Members of the society have a variety of safe equipment for observing the Sun.
The use of eclipse shades or #14 shade welding glass will allow you to observe this event and both are available from appropriate retailers but the method has the disadvantage that it does not magnify your view of the Sun. The disk of Venus will be clearly visible but the subtleties of the event (like the “black drop” effect when Venus leaves the solar disk) will not be discernible.
Projecting an image of the sun with binoculars or a small telescope will give you a magnified view of the sun on a white surface mounted behind the binoculars or telescope allowing several people to observe at the same time. But you must still be careful with this method; remember not to look through the binoculars or telescope to line up with the Sun (use the shadow they cast on the ground) and don’t observe for too long as the heat of the Sun passing through the optics can melt them!
Hints & Tips
Bright lights will not help you to observe and even if you are observing from a site unaffected by light-pollution your eyes will take up to 30 minutes to become fully ‘dark adapted’. So to avoid losing your dark adaption; and yet still be able to move around safely and read a star chart, use a red light source. This doesn’t have to anything specialist just cover a torch with a red sweet wrapper or use a rear bicycle light.
[Full Moon Graphic; Last Quarter Graphic; New Moon Graphic; First Quarter Graphic] – Graphics are taken from free planetarium software ‘Stellarium’.
Full Moon – Monday 4th June
Last Quarter – Monday 11th June
New Moon – Tuesday 19th June
First Quarter – Wednesday 27th June
For full details of any of the society events please contact us.
Starting June 2012:
R&DAS GCSE Astronomy Course
A one year astronomy course supported by a professional astronomy tutor
Tues 5th/Weds 6th June:
R&DAS Star Camp for the Transit of Venus
Anita’s Caravan Park, Mollington, Oxfordshire
Sunday 17th June:
R&DAS Monthly Meeting
19:30 – 21:30, Church Lawford Village Hall, School Street, Church Lawford
Mr Neil Parker, “The ‘Isaac Newton Group’ of Telescopes”
Wednesday 20th June:
19:00 – 20:00, North Leamington School, Sandy Lane, Leamington Spa
Dr Johanna F Jarvis, “Cosmic Cities”
Wednesday 11th July:
19:00 – 20:00, North Leamington School, Sandy Lane, Leamington Spa
Dr Johanna F Jarvis, “Twinkle Twinkle Little Star, How I Wonder...?”
How to contact R&DAS
Telephone: Johanna Jarvis 07739 716383