Category Archives: IAA

Lecture Programme

The lecture programme is held in association with the School of Mathematics and Physics, Queen’s University Belfast. It runs from September until the end of April and is held in the Bell Lecture Theatre in the Physics Building, main campus, Queen’s University, Belfast. Meetings start at 7.30pm sharp and consist of a short talk given by one of our members followed by the main lecture, usually given by a Professional Astronomer.   The lecture over, light refreshments are available free of charge. At this time members are free to mix and discuss the latest astronomical news and events. The meeting finishes at 10.00pm. Non-members are also welcome to attend!

The IAA Lecture Programme for 2019 – 20 commences on Wednesday 25th September at 19:30 in the Bell Lecture Theatre, QUB

IAA Lecture Programme, 2019 

Sep 25th    Dr Mike Simms (UM): “1969; a special year for space rocks (and not just from the Moon)” 
Oct 9th      Dr Gavin Ramsay (AOP): “Measuring the brightness of stars from space: flares, outbursts, exoplanets and the inside of stars” 
Oct 23rd    Dr Ernst de Mooj (QUB),  ‘Exoplanets’ 
Nov 6th     Mike Foylan (Cherryvalley Observatory) 
Nov 20th   Dr Meg Schwamb (QUB) “New Perspectives Big and Small of the Trans-Neptunian Region” 
Dec 4th     Dr Matt Redman, NUIG. “The shaping of planetary nebulae” 
Dec 18th   Members night – Brian Beesley and Adam Jeffers
IAA Lecture Programme 2020
January 4th: New Year Party.
January 8th: Dr Chris Watson (QUB) “The Terra Hunting Experiment – finding Alien Earthlike Worlds”
January 22nd: Dr A McCrea: “Return to the Moon”; T. Moseley: “The Closest Comet Approaches to Earth”
February 5th: Dr Andreas Sander (AOP) – “Rare but important: Why the Universe is shaped by massive stars”
February 19th: Dr Laura Murphy (TCD): “The First Stars in the Universe”
March 4th: Dr John Quinn (UCD): “Gamma-ray and Optical Astronomy with VERITAS”
March 18th: Prof Peter Gallagher: (tbc)
April 1st: Dr David Jess (QUB)
April 15th: AGM + Paul Evans “Apollo – The Rest of the story”

Past Lectures

IAA Lecture Programme 2018-19

Sep 19th – Dr Frank Prendergast, DIT: “From Neolithic to Iron Age – Case Studies in Irish Archaeoastronomy”
Oct 3rd –  Prof Luke Drury: Prof Emeritus, DIAS: “The Dawn of Multi-Messenger Astronomy”.
Oct 17th –  Prof Gerry Doyle, AOP: “The Probability of a Doomsday Solar Superflare: Fact or Fiction?”
Oct 31st –  Dr Marc Sarzi, AOP:  “Supermassive Black Holes” title tbc
Nov 14th –  Michael O’Connell. “Amateur Observations of Meteors”
Nov 28th –  Prof Stephen Smartt, ARC, QUB, “Kilonovae”
Dec 12th –  Paul Evans “Apollo 8 – Christmas Around the Moon”
Jan 5th 2019 – New Year Party
Jan 9th – tbc
Jan 23rd –  Dr Neale Gibson, ARC, QUB – “Exploring Alien Worlds: How to find life in the Universe”
Feb 6th –  Dr Simon Prentice, QUB –“The Cow: An incredible transient event”
Feb 20th –  Dr Jorick Vink, AOP, “Women in Astronomy: from the Maunder Mininum, to Leavitt and Hubble’s expanding Universe”
Mar 6th –  Prof Peter Gallagher, (ex TCD, new head of DIAS) tbc, prob on Parker solar Probe and I-Lofar
Mar 20th –  tbc
Apr 3rd –  Prof Alan Fitzsimmons, tbc
Apr 17th –  AGM

IAA Lecture Programme 2017 – 18

Sep 20th: Prof Mark Bailey, Emeritus Director of Armagh Observatory – “”Ancient Stones and Comets: Developing the Giant-Comet Hypothesis”

Oct 4th: Dr Sophie Murray, TCD: “Cloudy with a chance of flares: the importance of space weather forecasting”
Oct 18th: Dr Laura Keogh: InspireSpace: “Space law: owning stars, mining asteroids and Asgardia”
Nov 1st: Prof Tom Ray, DIAS: ‘Preparing for Science with the James Webb Space Telescope
Nov 15th: David Lisk, ‘Astronomical Spectroscopy for Amateurs’
Nov 29th: Dr Stuart Sim, QUB: ‘How Antimatter Formed’
Dec 13th: Andy McCrea & Terry Moseley: ‘Moon Shadow: The Great American Eclipse’


Jan 6th: New Year Party
Jan 10th: Brian McGabhann (Galway AC) – “Einstein made (relatively) simple”
Jan 24th : Prof Carl Murray (Queen Mary, Univ of London) –  “The Cassini Mission to Saturn: The End of an Era”
Feb 7th: Dr Stephen Wilkins (U of Sussex) “Exploring the End of the Dark Ages” 
Feb 21st: Dr Erin Higgins (AOP): “Live Fast and Die Young – Stellar evolution and the fate of massive stars”
Mar 7th: Dr Patrick Harkness (U of Glasgow) “Mars Sample Return technology: development and testing in Antarctica”
Mar 21st: Prof Alan Fitzsimmons, QUB – “First Contact: Uncovering An Interstellar Visitor.”
Apr 4th: Daniel Williams (U of Glasgow) ‘Gravitational waves’ exact title tba.
April 18th: AGM

IAA Lecture Programme 2016 – 17

Sep 21st: Prof Alan Fitzsimmons “Sungrazing Comets: Falling Into Hell”

Oct 5th: Dr Jose Groh (Asst Prof, TCD) “Live fast and die hard: the evolution and death of massive stars”
Oct 19th: Dr Morgan Fraser (UCD) “Gaia: Mapping the Milky Way and Beyond from Space”
Nov 2nd: Dr David Malone “How we tell the time”
Nov 16th: Members Night: Paul Evans: Beginners astrophotography’; Eleanor Edwards: ‘The Space Academy’
Nov 30th: Dr Wes Fraser:  “Recent space exploration: small guys take the spotlight”
Dec 14th: Aoife McCloskey TCD, “Sunspots and Solar Flares: How can we forecast space weather?”


Jan 4th: Prof Mike Burton, Director Armagh Observatory & Planetarium (AOP) “Explorers of the Galaxy”
Jan 7th: New Year Party
Jan 18th: Dr Kate Maguire “Cosmic Lighthouses: Supernovae and the Dark Universe”.
Feb 1st Dr Mike Simms, Ulster Museum “All Craters Great and Small”
Feb 15th: Dr Michele Bannister, QUB “Icy Wonders of the Outer Solar System”
Feb 22nd: Joint IAA/BGS meeting: Prof Sanjeev Gupta (ICL) ‘Exploring the Red Planet: Adventures of the Curiousity Rover”  Note, this is an extra date in the Calendar for NI Science Week.
Mar 1st: Dr Katja Poppenhaeger, QUB: “Exotic worlds: planets in other solar systems and what they might look like”.
Mar 15th:  Dr Cosimo Inserra of QUB, “Building bridges to the mysteries of our Universe with the brightest cosmic explosions”
Mar 29th: Dr Henry Joy McCracken, Institut d’Astrophysique de Paris. “The Euclid Mission: finding out what dark matter and dark energy really are”
April 12th: AGM

IAA Lecture Programme 2015 – 16 

Sep 23: Leo Enright: ‘Pluto, New Horizons, and the Edgeworth (Kuiper) Belt’

Oct 07: Terry Moseley –  “Our Sun: Friend or Foe?”

Oct 21: David Shayler, FBIS – “The Astronomer Astronauts”

Nov 4: Dr Maria Cullen, DCU: – “Anazoeing Mars”

Nov 18: Brian MacGabhann, GAC: “On the Shoulders of Giants; The Story of Our Quest to Understand the Cosmos”.

Dec 02: Prof Susan McKenna-Lawlor, NUIM, STIL: “Rosetta Mission, its Philae Lander, and the First Irish Satellite”

Dec 16: Tony Drennan (former IAA Pres) “ Sherlock Holmes, Pocahontas, and the Star Atlas with no stars”


Jan 02: IAA New Year Party, Comber. Details later.

Jan 06: Dr David Asher, Armagh Obs. “When Earth encounters interplanetary matter: bananas, wings and Totoro”

Jan 20: Dr Heather Cegla, QUB: ‘Earthlike Exoplanets’.

Feb 03: Prof Mihalis Mathioudakis: “What we’ll learn from the biggest solar telescope in the world”

Feb 17: Prof Andy Shearer, NUIG: “What we don’t know (Dark Energy and Dark Matter)”

Mar 02: Dr Nick Howes “The Biggest Telescope in the World” (ALMA)

Mar 16: Michael O’Connell, MAC: “The Antikythera Mechanism: The World’s Oldest Computer”.

Mar 30: Kevin Nolan (The Planetary Society) “An Emerging Cosmic Perspective

Apr 13: AGM + ??

Lecture Programme 2014


Sep 24th: Leo Enright: “Latest Science Results from Rosetta at the Comet”

Oct 8th: Prof Don Kurtz: “The Kepler Mission: Exoplanets and Asteroseismology”

Oct 22nd: Prof Lawrence Krauss: “Cosmic connections: from the Big Bang to life on Earth”
NB: this will be held in the Larmor Lecture Theatre, Physics, QUB.

Nov 5th: Prof Andy Shearer: “Big Telescopes, New Detectors, Fast Processing: the new era in astronomy”

Nov 19th: Dr Mike Simms  “What meteorites tell us about the early Solar System” 

Dec 3rd: Prof Tom Ray: “The Einstein Lens and a Tale of Two Eclipses”

Dec 17th: Dr Ernst De Mooij  (QUB) : Characterising the atmospheres of exoplanets


Lecture Programme 2015

Jan 3rd: New Year Party, details in form here….

Jan 7th: John Flannery (IAS) – “The Sky by Eye – How to Rediscover the Soul of Astronomy”

Jan 21st: Prof Alan Fitzsimmons: “Rosetta: The Final Picture of a Comet”

Feb 4th: Tom O’Donoghue: “Astrophotography: From Single Pane to Mega-mosaic”

Feb 18th: 
Dr Jorick Vink – “Star Formation in the Milky Way and in the early Universe” (Note change of lecture)

Mar 4th: Dr John Mason: “Mysteries of the Aurora”

Mar 18th: Paul Evans: “The Deep Partial Solar Eclipse of 20th March 2015”

April 1st: Dr Kate Russo and Terry Moseley: “The March 20 Total Solar Eclipse – What we saw”

April 15th: AGM.



Northern Ireland is a good place to see the Aurora Borealis, or Northern Lights. Not, perhaps, as good as Iceland, Northern Norway or Alaska, but if you happen to live here good displays can be seen and armed with a little information it is possible to plan a trip out with a few hours advance notice.

The best place to start is with a good location. It might, in extreme cases, be possible to see the lights from Central Belfast but it will be a far from ideal experience and you’ll always be better off leaving the city in search of better skies. The North Coast and spots along the Antrim Coast Road are generally good. You’re looking for a clear north horizon away from sources of light pollution. It doesn’t have to be looking across the sea though that is generally a good option.

You’ll need good sky conditions and the chart below gives you a clear sky forecast for Belfast which is generally a good indicator for most of the province, but if you want to be more specific clicking the chart will take you through to a site where you can enter your co-ordinates, town or postcode to get more specific results. Generally, we’re looking for green along the top line.

Next, we need to know whether there is potential activity or not. The Aurora is driven by a complex interaction of paticles from the Sun, the Solar Wind, and the Earth’s magnetic field. The wind is driven by such events as exploding sunspots causing Coronal Mass Ejections (CMEs), and other phenomena such as Coronal Holes. The arrival of such events at Earth can be detected by Magenetometers and the charts below show current and recent actvity as measured by magnetometers in Scotland and Lancashire – close enough to us to give an indication of the local circumstances. 

Auroral Activity

It is often the case that Earth will be hit by a blast of Solar Wind but there will be no Aurora and one of the common reasons for this is that the magnetic fields of the Sun and the Earth may not be working together. The Sun’s produces a magnetic field called the Interplanetary Magnetic Field (IMF) which can vary in polarity from North to South. It is shown on the graph below as the yellow line, Bz. With magnetism, identical poles repel and opposite poles attract, and we are near the North Pole, so if the IMF is also North there will be repulsion and the Aurora will be driven away from Earth. However if we have a southerly Bz – ie yellow line below centre, then we have good aurora potential. This is explained more comprehensively here…..

Next up is the Kp Index. This is a measure of overall geomagnetic activity in the upper atmosphere. It ranges from 0, which is no or very little activity, up to 9 which is the highest level of geomagnetic storm, rarely seen. Geomagnetic Storms are what we want to hear about when seeking out auroras and they range from G1 to G5, corresponding directly to activity levels of Kp5 to Kp9. Some will say that from Northern Ireland’s location it’s unlikely that we’ll see an aurora with a Kp less than 5 or 6, the fact is that Kp and Bz work together so that a favourable southerly Bz can produce an Aurora display even if the Kp is only 3 or 4.

This below is the OVATION-Prime model Aurora Forecast depicting the Auroral Oval and is probably the easiest to understand. It depicts the predicted aurora usng data drawn frm numerous sources. What we’re looking for of course is plenty of orange or red with the red line of visibility heading down towards Ireland!

More general informaton on the Aurora is available at the Aurora Service (Europe) site here….


The IAA is not responsible for the content of external websites.

General Astronomy and Space

  • The Jet Propulsion Laboratory

    The Jet Propulsion Laboratory is the central location for finding out about NASA’s many great scientific missions, like the remote control robots they’re playing with on Mars!

  • Cloudy Nights Telescope Reviews

    Mainly a great site for astronomy equipment reviews but also has many other articles about observing and general astronomy.

  • SpaceWeather

    A NASA site dealing with Solar astronomy and how it affects Earth. Notable for its display of realtime data and photography sent in by visitors to the site.

  • Heavens Above

    Excellent site for finding the ISS, Satellites, Iridium Flares, Asteroids, Comets and much more! This link sets the location as Belfast by default but the site has a user friendly location database for changing this.

  • The Flame Trench

    Excellent Space blog from Florida Today – lots of inside info from The Kennedy Space Center

  • Aurora Watch UK

    The Best source of UK Aurora information

  • The Independent Traveller

    Eclipse and Astronomy Travel

Telescopes etc

Run by Past President of the IAA Dr Andy McCrea, North Down Telescopes provides excellent friendly advice, competitive prices and delivery to anywhere in Ireland!

Everything you need to know about binoculars and what to see with them – Excellent site by Steve Tonkin

Ireland-wide Organisations

Amateur Astronomers’ Websites

Irish Astronomy Clubs, Societies, Associations etc

UK Sites

Software Resources

  • Deep Sky Stacker

    Free Stacking and Processing package for Deep Sky Objects taken with a DSLR

  • Registax

    Free Stacking and Processing package for Lunar and Planetary images taken with a webcam

  • Sharpcap

    Free capture utility for webcam imaging.

  • WX Astro Capture

    Free capture utility for webcam imaging. Windows and Linux versions – the Windows version can guide a scope too!

  • Stellarium

A Fully featured Planetarium on your Windows or Linux desktop – Free!

  • Cartes du Ciel

    Free star-mapping and telescope control

  • Virtual Moon Atlas

    For anyone who wants to find their way around our natural satellite, this is the tool for the job

Skyguide – with Neill McKeown


(Please note all times are ST and are based on an observing location of Belfast and covers the month of April)

The Sun

At the start of the month, the Sun rises at 06:55 and sets at 20:00. By month’s end, it rises at 05:50 and sets at 20:55.

The Planets

Special Event

3rd pm Venus in M45 – The Pleiades.

Regular Stuff

Mercury is not well placed for observation this month.

Venus is in the evening sky in Taurus. At the start of the month, it sets at 00:45 and by month’s end it sets at 01:05. It brightens from mag -4.3 to mag -4.4 during the month.

Mars is visible in the morning sky in Capricornus. At the start of the month, it rises at 05:10 and by month’s end it rises at 04:00. It brightens from mag +0.8 to mag +0.4 during the month.

Jupiter is at western quadrature on the 15th and is visible in the morning sky in Sagittarius. At the start of the month, it rises at 04:45 and by month’s end it rises at 02:55. It brightens from mag -2.0 to mag -2.2 during the month.

Saturn is at western quadrature on the 21st and is visible in the morning sky in Capricornus. At the start of the month it rises at 05:00 and by month’s end it rises at 03:10. It brightens from mag +0.7 to mag +0.6 during the month.

Uranus is at conjunction on the 26th. It is visible in the evening sky in Aries at the start of the month when it sets at 22:10 and is mag +5.9.

Neptune is not well placed for observation this month.

The Moon

The first quarter moon is on the 1st (11:21) with the full moon on the 8th (03:35). The last quarter moon is on the 14th (23:56) with the new moon on the 23rd (03:26). There is a 2nd first quarter moon on the 30th (21:38).

Regular Stuff

4th pm the 85% waxing gibbous lies N of Regulus (Alpha (α) Leonis, mag +1.4) at 22:00.

7th pm the near full moon lies N of Spica (Alpha (α) Virginis, mag +1.0) at 22:00.

8th pm the just past full moon lies E of Spica (Alpha (α) Virginis, mag +1.0) at 22:00.

11th am the 88% waning gibbous lies N of Antares (Alpha (α) Scorpii, mag +0.9) at 03:00.

12th am the 79% waning gibbous lies E of Antares (Alpha (α) Scorpii, mag +0.9) at 03:00.

14th am the 58% waning gibbous lies W of Jupiter at 05:00.

15th am the 48% waning crescent lies SE of Jupiter and SW of Saturn at 05:00.

16th am the 38% waning crescent lies S of Mars at 06:00.

25th pm the 7% waxing crescent lies W of Aldebaran (Alpha (α) Tauri, mag +0.9) and E of M45 – The Pleiades at 22:00.

26th pm the 13% waxing crescent lies SE of Venus at 23:00.


The best time to observe meteor showers is when the moon is below the horizon; otherwise its bright glare limits the number you will see especially the fainter ones. Below is a guide to this month’s showers.

The Lyrids peak on the morning of the 22nd with a ZHR of 18. The radiant is visible from 22:00 on the 21st and observing conditions are excellent with no moon interfering with this meteor shower.

There may be additional minor showers this month, details of which can be found in the below Information Sources and Links Section.


Asteroid (3) Juno is at opposition on the morning of the 3rd at mag +9.5 in Virgo and is visible from 22:00 on the 2nd.

Finder charts and further information about other fainter asteroids can be found in the below Information Sources and Links Section.


C/2017 T2 (PanSTARRS) is slowly brightening and is currently mag +9. It is predicted to remain around mag +8/9 until July. It will be circumpolar all month in Camelopardalis. It passes to the W of Gamma (γ) Camelopardalis, mag +4.6 on the night of the 11th/12th.

C/2019 Y1 (ATLAS) is currently mag +9 and predicted to remain at a similar brightness in April. It moves from Andromeda to Cassiopeia and to Cepheus during the month. It is very low at the start of the month, setting shortly after sunset but heads north and gains height and becomes circumpolar during the month. It passes to the W of Lambda (λ) Cassiopeiae, mag +4.7 on the night of the 7th/8th. It then passes to the W of Schedar (Alpha (α) Cassiopeiae, mag +2.2) on the night of the 9th/10th. On the nights of the 12th/13th – 14th/15th, it passes by several open clusters – NGC nos 129, 189, 103, 225, 146 and 133. On the night of the 14th/15th, it also passes to the E of Kappa (κ) Cassiopeiae, mag +4.2.

C/2019 Y4 (ATLAS) is currently mag +10 with predictions of peak brightness of mag +1 at perihelion on May 30th. It is circumpolar in Camelopardalis in April. It is visible from Ireland until mid-May when it is predicted to be mag +5.

Finder charts and further information about the above and other fainter comets can be found in the below Information Sources and Links Section. Any of the above estimates are based on current information at the time of writing the guide and can be wrong – “Comets are like cats; they have tails, and they do precisely what they want”, David H Levy.

Deep Sky

On the deep sky front this month, galaxies M81 and M82 can be observed in Ursa Major. In Leo, we have several galaxies on view including The Leo Triplet – M65, M66 and NGC 3628. M95, M96 and M105 can also be observed in Leo. The place to really find galaxies is in Virgo. The Virgo Super Cluster can be found here with numerous galaxies on view. Also in Virgo, M104 – the Sombrero Galaxy can be found. In Coma Berenices, there is M64 – the Black-Eye Galaxy. Also check out the constellation Canes Venatici with the globular cluster – M3 and several galaxies including M51 – the Whirlpool Galaxy and M63 – the Sunflower Galaxy. In Hercules, two globular clusters – M92 and the excellent M13 can be observed and in Lyra – M57 – The Ring Nebula can be observed. Finally there are some excellent open clusters in Cancer – M44 – The Beehive Cluster and M67.

General Notes

Always keep an eye out for Aurorae. Other interesting naked eye phenomena to look out for include the Zodiacal Light and the Gegenschein.

Both are caused by sunlight reflecting off dust particles which are present in the solar system. The Zodiacal Light can be seen in the West after evening twilight has disappeared or in the East before the morning twilight. The best time of year to see the phenomenon is late-Feb to early-April in the evening sky and September/October in the morning sky – it’s then that the ecliptic, along which the cone of the zodiacal light lies, is steepest in our skies. The Gegenschein can be seen in the area of the sky opposite the sun. To view either, you must get yourself to a very dark site to cut out the light pollution. When trying to observe either of these phenomena, it is best to do so when the moon is below the horizon. A new appendix has been added explaining some of the more technical terms used in the guide.

Clear Skies

Neill McKeown

The ZHR or Zenithal Hourly Rate is the number of meteors an observer would see in one hour under a clear, dark sky with a limiting apparent magnitude of 6.5 and if the radiant of the shower were in the zenith. The rate that can effectively be seen is nearly always lower and decreases as the radiant is closer to the horizon. The Zenith is the overhead point in the sky.

The radiant is the point in the sky, from which (to a planetary observer) meteors appear to originate, i.e. the Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. When the radiant is quoted as “circumpolar”, it is never below the horizon and visible all night, otherwise the times quoted are when the constellation in which the radiant lies rises above the horizon in the East.
A fireball is defined by the International Astronomical Union as a meteor brighter than any of the planets, i.e. magnitude -4 or brighter. The International Meteor Organisation alternatively defines it as a meteor which would have a magnitude of -3 or brighter at the zenith.
The ° symbol in the guide is that for degrees. A degree is two full moon widths to give an idea for judging any distances quoted in the guide. There are 60 arcminutes in a degree.
An asterism is a collection of stars seen in Earth’s sky which form simple patterns which are easy to identify, i.e. the Big Dipper. They can be formed from stars within the same constellation or by stars from more than one constellation. Like the constellations, they are a line of sight phenomenon and the stars whilst visible in the same general direction, are not physically related and are often at significantly different distances from Earth.
Mag is short for magnitude which is the measure of an object’s brightness. The smaller the number, the brighter the object. The brightest object in the sky is the Sun at mag -26, the full moon is mag -12 and Venus the brightest planet is mag -4. The brightest stars are mag -1. If there is a 1 mag difference between two objects – there is a difference in brightness of a factor of 2.5 between the two objects. For example the full moon is eight magnitudes brighter than Venus on average which means it is 1,526 times brighter than Venus. Objects down to mag +6 can be seen with the naked eye under very dark skies.
Local time is always quoted in the guide and this means for November – February – universal time (UT)/GMT is used and for April to September – daylight savings time (DST, = GMT+1). For the months of March and October when the clocks go forward/back respectively, both times will be used and attention should be paid to any times at the end of these months for that change.
Deep Sky Objects such as galaxies, nebulae and star clusters are classified in catalogues such as the Messier catalogue for objects like M44 – M for Messier. Another example of a catalogue would the New General catalogue whose objects have the prefix NGC. There are links for websites to both catalogues in the section above.
Perihelion is the point in the orbit of a planet, asteroid or comet where it is at the nearest point in its orbit to the sun. It is the opposite of Aphelion, which is when the object is at the farthest point in its orbit from the sun. For the earth, the comparative terms used are perigee and apogee and for the moon, pericynthion and apocynthion are sometimes used.

The Planets
From Earth – Mercury and Venus are the inner planets in the solar system and Mars, Jupiter, Saturn, Uranus and Neptune are the outer planets. Below is a short guide as to how both the inner and outer planets move around the sun. The above pictorial guide should hopefully help in this.
The Inner Planets
These are best seen when at Greatest Eastern/Western elongation and are not visible when at either Inferior/Superior conjunction. Greatest Eastern elongation is when the inner planet is at its furthest point east from the sun as seen from Earth and visible in the evening sky in the West after sunset, Western elongation is when it’s at its furthest point west from the sun as seen from Earth and visible in the morning sky in the East before sunrise. Inferior conjunction occurs when the inner planet is between the Sun and the Earth. Superior conjunction occurs when the inner planet is on the other side of the Sun as seen from Earth.
From our Northerly latitudes, the ecliptic, along which the planets move, lies at a very shallow angle to the horizon after sunset in the autumn and before sunrise in the spring. This means that any of the planets will be difficult to see when fairly close to the Sun in the evening sky in the autumn or in the morning sky in the spring. In particular, Mercury is more or less invisible from here when at Eastern elongation in the autumn or at Western elongation in the spring, because it lies so close to the horizon and is never above the horizon except in daylight or bright twilight.
The normal cycle for an inner planet is Superior Conjunction – Greatest Eastern Elongation – Inferior Conjunction – Greatest Western Elongation – Superior Conjunction. After superior conjunction, the planet moves away from the Sun as seen from Earth and becomes visible in the evening sky after a period of time. It then moves past the point of Greatest Eastern Elongation and moves back towards the Sun as seen from Earth until a point when it is not visible and at Inferior Conjunction. After this the planet appears in the morning sky for a time, before again slipping into the Sun’s glare as seen from Earth. The duration of this cycle will depend on the planet’s closeness to the Sun, i.e. Mercury completes the above cycle in around 4 months.
The Outer Planets
These are best seen when at opposition and are not visible when at conjunction. Opposition occurs when the earth is between the sun and the outer planet. It is the best time to observe them because the planet is visible all through the night and it is due South and at its highest at about midnight. The planet is also at its closest point in its orbit to Earth – making it appear brighter. Conjunction occurs when the outer planet is on the other side of the Sun as seen from Earth.
If the planet is at or near it furthest point South along the ecliptic, then it won’t get very high in the sky even at opposition – just as the Sun never gets high in the sky in midwinter. This happens when opposition occurs near midsummer when the planet is opposite the Sun in the sky and in midsummer the Sun is high, so the planet will be low. The opposite of course applies in winter.
The normal cycle for an outer planet is Conjunction – Western Quadrature – Opposition – Eastern Quadrature – Conjunction. After conjunction, the planet moves away from the Sun as seen from Earth and becomes visible again. The planet from this point on rises earlier and earlier in the morning sky and eventually becomes visible in the evening sky. At Western Quadrature it is at its highest at sunrise and by opposition it is in the same position by midnight. By Eastern Quadrature, it is past its best and is at its highest at sunset, meaning it is rising in daytime and setting earlier and earlier until a point when it sets too close to the Sun as seen from Earth and is no longer visible. The duration of this cycle will depend on the planet’s closeness to the Sun, i.e. Jupiter completes the above cycle in around 13-14 months.

About Us

The Irish Astronomical Association was formed in 1974 and draws its 200+ members from both the UK and Ireland. The IAA membership ranges from complete beginners to accomplished observers and astrophotographers.
The lecture programme is held in association with the School of Mathematics and Physics, Queen’s University Belfast. It runs from September until April and is held in the Bell Lecture Theatre in the Physics Building, main campus, Queen’s University, Belfast.
Meetings start at 7-30pm sharp and consist of a short talk given by one of our members followed by the main lecture, usually given by a professional astronomer. The lecture over, light refreshments are available free of charge.  At this time members are free to mix and discuss the latest astronomical news and events. The meeting finishes at 10.00pm.
Non-members are also welcome to attend,and of course regular attendees are expected to become members!
The Association also runs an observing programme where beginners of all ages can be guided around the night sky by more experienced members and get to see objects through the Association’s Meade Lightbridge 16″ telescope!
Members will be sent our highly regarded magazine “Stardust” every three months.
Throughout the year the Association runs an outreach programme where we visit various venues throughout the province, often with the Planetarium’s Stardome as well as displays of meteorites and other astronomical paraphenalia. During daytime sessions solar observing is usually on offer – weather permitting of course – and this allows members of the public to see our nearest star through special telescopes designed for safe viewing, filtered to emphasise features on the Sun’s surface, such as sunspots, prominences and so on. Night time observing sessions will of course feature telescopic observations of the Moon, planets and deep-sky objects.
The IAA is governed by a Council elected by the members at the Annual General Meeting, traditionally being the last meeting of the season towards the end of April.


IAA Lecture