October 2023 Observing Guide

Hi all,PLEASE NOTE THE BELOW SUMMARY AND GUIDE IS FOR AN APPROXIMATE LATITUDE OF 55 DEGREES NORTH In October, there are two highlights. The Orionid meteor shower peaks on the night of the 21st/22nd with meteors visible from midnight. The moon will have set so it is not an issue. If you have dark skies away from light pollution, you may see 10-15 meteors/hour.  There is a partial lunar eclipse on the evening of the 28th. The eclipse begins at 20:35, with max eclipse at 21:14 when 12% of the moon is inside the umbra (the Earth’s inner shadow). The eclipse ends at 21:52. The portion of the moon that is inside the umbra will appear a reddish colour.OBSERVING GUIDE(Please note all times are ST unless otherwise stated and are based on an observing location of Belfast and covers the month of October)

The Sun

At the start of the month, the Sun rises at 07:25 and sets at 19:00. By month's end, it rises at 07:25 UT and sets at 16:50 UT. The Planets Regular Stuff Mercury is at superior conjunction on the 20th and is visible in the morning skies at the start of the month in Virgo when it rises at 06:00 and is mag -1.0.
Venus is at greatest western elongation on the 24th and is visible in the morning sky this month in Leo. It rises at 03:25 at the start of the month and at 02:55 UT by month’s end. It fades from mag -4.4 to mag -4.2 during the month.

Mars is not easily visible this month.

Jupiter is visible in the evening sky this month in Aries. It rises at 20:05 at the start of the month and at 17:00 UT by month’s end. It brightens during the month from mag -2.7 to mag -2.8. Saturn is visible in the evening sky this month in Aquarius. It rises during daylight hours during the month and sets at 00:40 UT by month’s end. It fades during the month from mag +0.6 to mag +0.7.
Uranus is visible in the evening sky this month in Aries. It rises at 20:15 at the start of the month and at 17:15 UT by month’s end. It brightens from mag +5.7 to mag +5.6 during the month.
Neptune is visible in the evening sky this month in Pisces. It rises during daylight hours during the month and sets at 03:10 UT by month’s end. It maintains its brightness during the month at mag +7.8. The Moon

The last quarter moon is on the 6th (14:48). The new moon is on the 14th (18:55). The first quarter moon is on the 22nd (04:29). The full moon is on the 28th (21:24). Lunar Eclipse There is a partial lunar eclipse on the evening of the 28th. The eclipse begins at 20:35, with max eclipse at 21:14 when 12% of the moon is inside the umbra (the Earth’s inner shadow). The eclipse ends at 21:52. The portion of the moon that is inside the umbra will appear a reddish colour.   Regular Stuff  1st pm the 92% waning gibbous lies above right of Jupiter at 21:00.2nd pm the 85% waning gibbous lies left of Uranus and right of M45 – The Pleiades at 21:00.3rd pm the 76% waning gibbous lies above Aldebaran (Alpha (α) Tauri, mag +0.9) and below left of M45 – The Pleiades at 22:00.10th am the 18% waning crescent lies above Venus and Regulus (Alpha (α) Leonis, mag +1.4) at 04:00.11th am the 11% waning crescent lies below left of Venus and Regulus (Alpha (α) Leonis, mag +1.4) at 04:00.23rd pm the 68% waxing gibbous lies below right of Saturn at 20:00.24th pm the 79% waxing gibbous lies below left of Saturn at 20:00.25th pm the 88% waxing gibbous lies below right of Neptune at 20:00.26th pm the 94% waxing gibbous lies below left of Neptune at 20:00.28th pm the full moon lies above right of Jupiter at 20:00.29th pm the 99% waning gibbous lies left of Jupiter and above right of Uranus at 19:00.30th pm the 95% waning gibbous lies below M45 – The Pleiades at 19:00.31st pm the 89% waning gibbous lies above left of Aldebaran (Alpha (α) Tauri, mag +0.9) at 19:00. Meteors

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 Orionids peak on the night of the 21st/22nd with a ZHR of 20. The radiant rises around midnight and with the near first quarter moon setting at 22:15 on the 21st, this is a good year for this shower. There may be additional minor showers this month, details of which can be found in the below Information Sources and Links Section. 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. Asteroids

Asteroid (29) Amphitrite is at opposition on the morning of the 2nd and is mag +8.8 in Pisces. It will be visible as soon as darkness falls on the evening of the 1st. Finder charts and further information about other fainter asteroids can be found in the below Information Sources and Links Section.

Comets

There are no bright comets easily visible this month. 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. “If you want to have a safe gamble, bet on a horse - not a comet”, Dr Fred Whipple.          Deep Sky On the deep sky front this month, galaxies M81 and M82 can be observed in Ursa Major. In Lyra - M57 - The Ring Nebula can be observed and in Vulpecula - M27 - The Dumbbell Nebula can be found. In Andromeda, M31 - The Andromeda galaxy can be observed along with its satellite galaxies M32 and M110. In Perseus, there is the open cluster M34 and the excellent Double Cluster - NGC 869 and 884. In Triangulum, there is the galaxy M33. Auriga reappears with its three open clusters M36, M37 and M38 as does Taurus with the excellent Pleiades - M45 and the Hyades. Orion returns to our skies with M42 - The Great Orion Nebula along with Gemini with the open cluster M35. General Notes Always keep an eye out for Aurorae. On the morning of the 29th at 2am, the clocks go back one hour and summer time ends. 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 McKeownInformation Sources and LinksSky at Night Magazine Observing Guide – All RounderStardust Magazine – All RounderPhilip's Stargazing 2023 – All RounderCollins 2023 Guide to the Night Sky – All RounderYearbook of Astronomy 2023 – All Rounder2023 calendar of annual Astronomical events by John Flannery – All RounderSky Safari App – All RounderStellarium App – All Rounder in-the-sky.org/ – All Rounder www.nightskyhunter.com/ - All Rounder www.heavens-above.com – All Rounder www.timeanddate.com/astronomy/ - All Rounder www.irishastronomy.org  - Irish Federation of Astronomy Societies Website and Calendar – All Rounder irishastro.org.uk/ - Irish Astronomical Association website – All Rounder www.eaas.co.uk  - Northern Ireland Amateur Astronomy Society – All Rounder eco.mtk.nao.ac.jp/cgi-bin/koyomi/cande/phenomena_en.cgi – Sun/Planets/Moon Only cal2023.pdf (imo.net) - International Meteor Organisation 2023 Meteor Shower Calendar www.cobs.si – Comet Observation Database www.aerith.net – Comets Only www.ast.cam.ac.uk/%7Ejds/ - Comets Only astro.vanbuitenen.nl – Comets Only theskylive.com/ - Comets/Asteroids messier.seds.org/ - The Messier Catalogue website – Deep Sky Only www.spaceweather.com – Aurorae Forecasts/Naked Eye Atmospherics astro.ukho.gov.uk/eclbin/query_eo.cgi - Eclipses Appendix

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 full moon’s width when viewed from the Earth is 30 arc minutes or ½ a degree. This should give an idea for judging any distances quoted in the guide.

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. A conjunction is when two objects appear to be close to each other in the sky according to the perspective of the observer. 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. 
 

 

Hi, Can't edit my Astro guide. When I click on edit, I get the above error, Help!

Yep, clicking 'Reply Topic' doesn't work either, only 'Quick Reply'. There used to be a Darren guy behind the site operation, not sure who's in charge now.

Finbarr.

I have been noticing that too, Finbarr.
Maybe Michael Murphy can contact the powers that be.
I also see that the emojis are gone.

I've mentioned this to Darragh Sherwin (he hosts the site). The software was upgraded recently and this seems to be the source of all the issues.

Michael.

Hi,

What is the latest re the new software/forum issues?

Thanks

Neill