International Space Station and Jules
The International Space Station (ISS) orbits are now conveniently positioned
for viewing in our UK evening skies. The European Space Agency's resupply
vessel, Jules Verne is manouvering close to the ISS for a planned docking on
April 3rd which will add interest to any observations.
There are two visible passes most evenings for the next week and you can get
times and directions for your location from the excellent web site at www.heavens-above.com You need to select your
location if you aren't already registered with the site. If your search for
passes doesn't give you any then check that your location is set correctly. You can do
this easily by choosing the 'select from database' option. Choose your country, search
on your town of village name then select the correct option from the search
There will be two passes tomorrow evening when we plan
to have our April 1st Star Party (to which you are invited - just turn up, there is no need to
book). The first starts at 19:57:04 so we will bring forward the start of
the party to 7:45 pm. The second pass starts at 21:31:53 and each lasts between
two and three minutes. Both are bright; the first is magnitude -1.9 and the
second is even brighter at -2.5.
The best way to see the ISS is to use your naked eye and look
towards the south-western horizon for the first pass and the western horizon for
the second. Once you spot the ISS you can use binoculars to follow it.
Experienced observers with computer-controlled telescopes might like to try
My thanks to Dave Eagle and Peter Ashwell from Bedford Astronomical Society
for drawing my attention to this.
Iridium Flares and Other Satellites
While visiting the Heavens Above site why not make note of Iridium flare
predictions and other bright satellites. Iridium flares are caused by sunlight
reflected from the Main Mission Antennae on a fleet of communications satellites
in low-earth orbit (around 780 km). It is sometimes possible to spot the
satellite before the flare and to watch it brighten and fade again as the
sunlight glints off an antenna.
For more information on observing Iridium satellites see
the help page on Heavens
Predictions are given for other bright satellites as well. For example,
tonight there are nine satellites brighter than magnitude 3.5 (easily seen in a
clear sky) that are visible from Green Witch between 9 pm and 11:10 pm local
In the last newsletter I suggested getting ready to take images of Venus in
the late summer. The European Space Agency is encouraging amateur astronomers to
do this to supplement observations taken with the Venus Express space craft.
If you like the idea of contributing to a space mission then visit ESA's
VAOP Page for advice on equipment, observing techniques and how
to submit your images. Take a look at the ground-based archive to see some of
the images submitted so far. Click on an image for details of the observer
and equipment used. At the time of writing the 8th and 9th most active imagers
had only one image accepted so there is lots of potential for you to make an
impact. If your image is used in a scientific paper you will receive credit for
If you've seen April's edition of Astronomy Now you may have noticed
the first issue of Starlight, an 8-page pullout designed for children
between the ages of ten and fourteen. If you have children in this age range and
don't already subscribe to Astronomy Now you might like to consider
doing so. If you're already a subscriber and don't have children who would
appreciate it, why not pass Starlight on to a neighbour. You might
ignite a lifelong interest and just think how good that would make you feel.
Kelling Spring Sky Camp
The Spring Sky Camp will be held at Kelling Heath from Thursday 3rd to Sunday
6th April. Wendy and Ralph plan to be there on Saturday so please give them a
call if you would like them to bring anything in particular. The Spring Sky Camp
is a less formal affair than the Autumn Camp and you can find details here.
Cassini - preliminary results from the close encounter with
It appears that Enceladus is warmer than expected and the
composition of its geysers resembles that of comets. These are two of the first discoveries from the recent fly-bys
prompting scientists to get excited about the possibility of liquid water existing below
the surface together with organic chemicals and warmth. If there is liquid
water then the chances of finding some form of life increase
Last night the sky was quite clear where I live and as I browsed the sky
Arcturus seemed to be much redder than I remember. I don't think it has changed
in any way so assume the conditions and my eyes were good for seeing colour.
Arcturus is a red giant star with a mass thought to be between one and one and a
half times the Sun's mass. It is thus a good example of what the Sun is likely
to become as it nears the end of its life.
Arcturus is the third brightest star in the night sky although it appears to
be the fourth as the close binary pair of Alpha Centauri look like a single star
that is brighter. Arcturus is the brightest star in the northern hemisphere and
the second brightest star we can see from the UK after Sirius (which is south of
the celestial equator).
It is in the constellation of Bootes and it is easy to find by following the
arc of the plough's handle. The name derives from ancient greek and means 'Bear
Guard' being close to the Great and Little Bears.
During the commissioning phase of the William Herschel Telescope on La Palma
George Isaacs from Birmingham University observed Artcturus for three weeks with
a very sensitive red-shift monitor to try to detect a wobble that would indicate
the presence of an extra-solar planet. No such planets had been discovered at
that time and George's observations only set an upper limit for the size of a
planet, should one exist in orbit around Arcturus.
In 1933 the Chicago World's Fair was opened by light from Arcturus. At that
time it was thought that the light would have left Arcturus at the time of the
previous Chicago World's Fair in 1893. Current estimates gives its distance as
36.7 lightyears so it would have started its journey in 1896 but it was a neat
idea. Perhaps we should link Earthly events more closely with the stars to
remind city dwellers that they are there.
Looking South at 10 pm from Cambridge, UK
Because of the change to BST the sky appears not to have moved on since the
last newsletter so I'll just mention one thing for you to look at. Saturn is
very close to Regulus in Leo and the two make a fine pair that is easy to
identify. At present Saturn is undergoing retrograde motion, ie it appears to be
moving westwards relative to the stars and is getting closer to Regulus. This
apparent motion is due to our point of view moving with the Earth.
At its closest, Saturn will be just over two degrees from Regulus then will
move away from it as it continues its normally eastwards motion. Why not watch
it closely throughout April and see if you can detect when it changes direction.
You can always check your answer with a program such as SkyMap Pro
I was in the Alps in Southern France last week expecting clear dark skies at
night as we had beautiful blue skies during the day. I was disappointed that the
faintest stars I could see were between third and fourth magnitude. It made me
realise just how dark and clear the skies are in Arizona. There I can see the
Milky Way from horizon to horizon without waiting for my eyes to dark adapt. If
you haven't experienced this why not book a holiday at the Green Witch house.
The exchange rate makes it very cost-effective and there is a lot more to do
besides astronomy. Take a look at our web site at www.arizonaskyvillage.co.uk to see
if it's for you.
Clear Skies and Best Wishes