MEETINGS
JUNE
MEETING
As in previous years, and since these are the shortest
nights of the year, the June meeting is held open to members as a Telescope
Evening when telescopes and equipment of interest to other members is welcome.
The meeting began with
He went on to demonstrate how to collimate a Newtonian
using a laser collimator, stressing the importance to finding and marking the
centre point of the main mirror.
John explained how all the elements had to be aligned
in a particular order to achieve correct collimation.
In the June Newsletter there was a report of the Angus
Meeting which encourages a hands-on approach to astronomical equipment, in
which Angus Macdonald introduced the idea of adapting a Dobsonian mounted
telescope for use by the observer which obviates the need to move the actual
tube.
Angus had brought his Dobsonian to the meeting and
described the reasoning behind the construction of the modifications. He explained that his interest had been
aroused in finding a solution to allow viewing through his telescope when he had
experienced repeated back pain when moving and setting up the telescope.
He demonstrated how, with the addition of an optically
flat mirror in front of the tube (angled at 45 degrees) it was possible to
rotate it and view the entire sky from a seated position with the telescope in
a horizontal plane.
A number of questions were asked and members had the
opportunity to try out the instrument later during the tea break.
Following Angus, Phil Berry gave a short presentation
on the subject of occultations. At a
previous meeting, Brian Mills had given a talk on the subject and Phil said he
had been bitten by the bug and was keen to try out observations for himself.
He gave a brief overview of the various types of lunar
occultation; e.g. “Total” and “Grazing”, and showed slides to demonstrate how
the moon’s shadow was actual size on Earth because stars are so far away that
their light rays are considered parallel.
He described the placing of observers to see a graze occultation.
Phil then discussed asteroidal occultations and gave
some impressive examples of work by amateurs who had been able to determine in
some detail, the size and two-dimensional shape of asteroids by the occultation
method.
He described some new gadgets he had acquired and spoke
about using video cameras with accurate time overlays to record such events.
Here are the URLs Phil referred to during his
presentation:
•
http://www.occultations.net/
(An
Introduction to Astronomy Occultations)
•
http://www.occultations.org/
(International
Occultation Timing Association – an introduction to accurate timings necessary
for Occultation Observing)
•
http://www.pic-osd.com/
(GPS
Video Overlay Units – Hardware to aid accurate timing of Occultations)
•
http://www.lunar-occultations.com/iota/occult4.htm
(Occultation
Prediction Software)
Brian Mills then spoke about the construction of his
observatory in Hildenborough where the recent Angus Group meeting had been
held.
He showed slides of the construction from foundations
to completion and then described how he had replaced the original dome with a
lighter alternative and how he had suffered a selection of broken ribs when he
fell from a stepladder during the process.
He finished by showing a picture of his other
observatory – the roof of his bungalow!
He described how he climbs onto the roof every July and August to get a
first class view of the Perseids meteor shower.
Brian also mentioned how he is prone to dropping off
(to sleep – not off the roof) whilst observing and said that on one occasion he
began a meteor watch under clear skies only to nod off and awaken with the sky
completely cloudy!
Following the tea break our Director of Observations,
Brian Mills, gave a brief presentation about the night sky. He reminded those present about how to find
Boötes and Corona Borealis and how to use these to find Hercules.
From Hercules it was possible to find Antares, the
brightest star in Scorpio, which was visible at this time of year although it
was quite close to the horizon. From
there, the constellations of Libra, Serpens and Orphiuchus could all be fund.
Brian described briefly the globular cluster in
Hercules (M13) and said how Harlow Shapley had shown that Cepheid variables
could be used as standard candles to determine the distance of such clusters.
He then showed maps of the current locations of Saturn
and Jupiter and spoke briefly about some upcoming lunar occultations that would
be easily viewable with the Society’s telescopes, should anyone care to borrow
them.
He closed by mentioning the total eclipse that will
occur on July 22nd and said that live feeds would again be available
via the Internet.
Brian
refers to this in “The July Sky Notes”
JULY
MEETING
Wednesday 15th July 2009 “The Virtual Observatory”. Five years ago John Murrell gave an excellent
talk about accessing the vast amount of data available on the internet. At the July meeting, John will be giving more
information on the subject with a lot of updates. John Murrell is a member of the Croydon
Astronomical Society and it is worth visiting his web site at:
http://johnmurrell.org.uk/
The
meeting begins at 1930 although members are invited to arrive anytime after
1900 as this is a good time to exchange ideas and discuss problems and relax
before the talk.
The venue
as always is in the Upper Room of the
FUTURE
MEETINGS
Saturday 29th August 2009 – Worth
putting in your diary. There is no
meeting of the Society in August but
In the past some of us have taken along
telescopes, binoculars and anything else we think would be useful to see the
night sky in late August.
In the
past the weather has been variable so this year we must be owed a good clear
evening.
Any member
of the Society is welcome to bring drink and food to cook on a barbecue and
then take advantage of the darkening skies to view whatever is in the sky at
that time.
Michael
suggests that members aim to arrive about 1900
There will
be further details in the August Newsletter.
Wednesday 16th September 2009 – “The
Apollo Programme – Missions 13 to 17”
This is a continuation of the talk given by
Wednesday 21st October 2009 - “Astro-archaeology
in the
OTHER NEWS
AND INFORMATION
SKY NOTES
FOR JULY
Planets
Mercury is not visible during July, passing through superior
conjunction on the 14th. This is where Mercury, the Sun and the
Earth all line up with Mercury on the far side of the Sun (behind it).
Venus is a morning object at magnitude -4.0 rising three
hours ahead of the Sun by the middle of the month, lying in the constellation
of Taurus.
Mars is a morning object (also in Taurus) at magnitude +1.1
rising just over three hours before the Sun. For the rest of this year Mars
will increase in both magnitude and apparent diameter.
Jupiter on the Aquarius/Capricornus borders rises around 22.30
BST by the middle of the month although it never rises very high above the
horizon. This is because at this time of year the ecliptic is low down during
the hours of darkness. However, to compensate for this Jupiter shines at
magnitude -2.7. On July 10th it passes around half a degree south of
Saturn is still just visible in the western sky but is
gradually being absorbed by the twilight. It shines at magnitude +1.1 in Leo,
very much in the same position as for the last few months as shown by the
crosshairs below. By the end of the month it sets by around 22.00 BST.
Lunar Occultations
As usual in the table I’ve only included events for
stars down to around magnitude 7.5 that occur before midnight. DD = disappearance
at the dark limb and RD = re-appearance at the dark limb. Times are BST.
July |
Time |
Star |
Mag. |
Ph |
PA ° |
1st |
21.35 |
SAO 158468 |
6.9 |
DD |
56 |
3rd |
21.58 |
SAO 184047 |
7.5 |
DD |
120 |
3rd |
22.46 |
SAO 184068 |
5.0 |
DD |
30 |
27th |
21.09 |
SAO 157778 |
6.9 |
DD |
42 |
30th |
23.43 |
SAO 183854 |
4.6 |
DD |
121 |
Lunar Occultations of the Pleiades
In the early hours of Saturday July 18th the
Moon passes in front of M45, the Pleiades open cluster in Taurus. There are a
whole series of events (24 in total) that morning, but for anyone interested I
have listed the brightest below. For those who live further north and west
there is the chance to see a grazing occultation of Alcyone. DB = disappearance
at the dark limb. Times are BST.
Time |
Star |
Mag. |
Ph |
PA ° |
02.59 |
Alcyone |
2.8 |
DB |
5 |
03.00 |
Merope |
4.1 |
RD |
294 |
03.19 |
Alcyone |
2.8 |
RD |
322 |
04.10 |
Pleione |
5.1 |
RD |
293 |
04.11 |
Atlas |
3.6 |
RD |
274 |
Phases of the Moon for July
For convenience I have added the rising and setting
times (in BST) for the phases listed below.
Full |
Last ¼ |
New |
First ¼ |
|
7th |
15th |
22nd |
28th |
|
21.37 |
23.41 |
05.21 |
13.55 |
Rise |
04.31 |
14.06 |
21.17 |
22.58 |
Set |
Meteors
One of the more productive showers of the year, the
Perseids, begins on July 23rd. The radiant lies fairly low down in
the north east at the start, but gradually gains altitude as the shower
progresses towards maximum. This means that in the early part of the evening,
many events are lost either below the horizon or into the haze that often
prevails if the weather has been hot. However, it is still an excellent
observational target as the Perseids contain a large proportion of bright and
fast meteors with many leaving ionised trains.
ISS
There are a large number of passes of the ISS as seen
from Wadhurst this month. I have only included those that attain reasonable
altitude and occur before midnight. See www.heavens-above.com for a complete
list of all passes. Please remember that the time below is when the ISS is at maximum altitude, so you should begin
looking a few minutes beforehand. Times
are BST.
Date July |
Mag |
Time BST |
Alt. |
|
6th |
-2.5 |
23.14 |
30 |
SSE |
7th |
-3.4 |
23.38 |
59 |
SSE |
8th |
-2.6 |
22.27 |
31 |
SSE |
9th |
-3.4 |
22.52 |
61 |
SSE |
10th |
-2.5 |
21.41 |
32 |
SSE |
10th |
-3.4 |
23.16 |
87 |
N |
11th |
-3.3 |
22.05 |
62 |
SSE |
11th |
-3.2 |
23.40 |
76 |
N |
12th |
-3.3 |
22.30 |
86 |
N |
13th |
-3.3 |
21.19 |
63 |
SSE |
13th |
-3.2 |
22.54 |
76 |
N |
14th |
-3.3 |
21.43 |
85 |
N |
14th |
-3.4 |
23.18 |
89 |
S |
15th |
-3.2 |
22.07 |
76 |
N |
15th |
-3.2 |
23.42 |
55 |
SSW |
16th |
-3.4 |
22.32 |
88 |
SSW |
17th |
-3.1 |
21.21 |
77 |
N |
17th |
-3.2 |
22.56 |
54 |
SSW |
18th |
-3.3 |
21.45 |
87 |
S |
18th |
-2.1 |
23.20 |
27 |
SSW |
19th |
-3.0 |
22.09 |
53 |
SSW |
20th |
-2.0 |
22.33 |
26 |
SSW |
21st |
-2.9 |
21.22 |
52 |
SSW |
Iridium Flares
The flares that I’ve listed are only the brightest,
there are many more that are fainter, occur at lower altitudes and also after
midnight. I’ve included one or two that do occur low down but to compensate
they are quite bright. If you wish to see a complete list, go to
www.heavens-above.com Times are all BST.
Jul |
Time |
Mag |
Alt° |
|
4th |
23.09 |
-7 |
26 |
NNE |
5th |
21.29 |
-7 |
61 |
NE |
9th |
22.49 |
-6 |
34 |
NE |
14th |
22.28 |
-4 |
41 |
NE |
19th |
23.30 |
-5 |
12 |
NNE |
20th |
22.01 |
-8 |
51 |
NE |
27th |
21.28 |
-3 |
60 |
ENE |
27th |
23.02 |
-7 |
27 |
NE |
28th |
22.57 |
-3 |
28 |
NE |
Total Solar Eclipse
On July 22nd there is a total eclipse of the
Sun as seen from
http://www.live-eclipse.org or
http://exploratorium.edu/eclipse/2009/index.html
The
NASA web site is also full of useful and interesting information at:-
http://eclipse.gsfc.nasa.gov/SEmono/TSE2009/TSE2009.html
Some Summer Constellations
At the June meeting I spoke about how to find some of
the constellations in the Hercules area by starting off with the Plough and
Boötes as earlier described in “Constellation Recognition No. 3”. It is then
possible to locate Hercules, Ophiuchus and Scorpio. From these it is a simple
task to find Libra and the two separate sections of Serpens. All four of the
“Constellation Recognition” maps and instructions are available at meetings.
Apologies for incorrectly spelling Ophiuchus on map no. 4, but the notes have
it correctly.
Advance Warning for August
12/13th August - Perseid maximum
Brian Mills
The Cool
Chemistry of Alien Life
Alien life
on distant worlds! What would it be like? For millennia people could only
wonder, but now NASA’s Spitzer Space Telescope is producing some hard data. It
turns out that life around certain kinds of stars would likely be very
different from life as we know it.
Using
Spitzer, astronomers have discovered the organic chemical acetylene in the planet-forming
discs surrounding 17 M-dwarf stars. It’s the first time any chemical has been
detected around one of these small, cool stars. However, scientists are more
intrigued by what was not there: a
chemical called hydrogen cyanide (HCN), an important building block for life as
we know it.
“The fact
that we do not detect hydrogen cyanide around cool stars suggests that that
prebiotic chemistry may unfold differently on planets orbiting cool stars,”
says Ilaria Pascucci, lead scientist for the Spitzer observations and an
astrophysicist at
That’s
because HCN is the basic component for making adenine, one of the four
information-carrying chemicals in DNA. All known life on Earth is based on DNA,
but without adenine available, life in a dwarf-star solar system would have to
make do without it. “You cannot make adenine in another way,” Pascucci
explains. “You need hydrogen cyanide.”
M-dwarf
and brown dwarf stars emit far less ultraviolet light than larger, hotter stars
such as our sun. Pascucci thinks this difference could explain the lack of HCN
around dwarf stars. For HCN to form, molecules of nitrogen must first be split
into individual nitrogen atoms. But the triple bond holding molecular nitrogen
together is very strong. High-energy ultraviolet photons can break this bond,
but the lower-energy photons from M-dwarf stars cannot.
“Other
nitrogen-bearing molecules are going to be affected by this same chemistry,”
Pascucci says, possibly including the precursors to amino acids and thus
proteins.
To search
for HCN, Pascucci’s team looked at data from Spitzer, which observes the
universe at infrared wavelengths. Planet-forming discs around M-dwarf stars
have very faint infrared emissions, but Spitzer is sensitive enough to detect
them.
HCN’s
distinctive 14-micron emission band was absent in the infrared spectra of the
M-dwarf stars, but Spitzer did detect HCN in the spectra of 44 hotter, sun-like
stars.
Infrared
astronomy will be a powerful tool for studying other prebiotic chemicals in
planet-forming discs, says Pascucci, and the Spitzer Space Telescope is at the
forefront of the field. Spitzer can’t
yet draw us a picture of alien life forms, but it’s beginning to tell us what
they could—and could not—be made of. “That’s pretty wonderful, too,” says
Pascucci.
For news
of other discoveries based on Spitzer data, visit:
www.spitzer.caltech.edu
Kids can
learn Spitzer astronomy words and concepts by playing the Spitzer “Sign Here!”
game at :
spaceplace.nasa.gov/en/kids/spitzer/signs.
This article
was provided by the Jet Propulsion Laboratory, California Institute of
Technology, under a contract with the National Aeronautics and Space
Administration.
CONTACTS
Chairman
pjvalet1@tiscali.co.uk
Treasurer
mike31@madasafish.com
Editor
geoff@rathbone007.fsnet.co.uk
Events
phil.berry@tiscali.co.uk
Director of
Observations Brian Mills 01732
832691
Brian@wkrcc.co.uk
Wadhurst
Astronomical Society website:
www.wadhurst.info/was/
SAGAS web-site www.sagasonline.org.uk
Any material
for inclusion in the August 2009 Newsletter should be with the Editor by 28th July
2009