With the dark nights upon us, October is a great month to get into stargazing. There is lots of see including the Orionids meteor shower, chances to spot Mars, Mercury, Venus, and the Blue Moon at the end of the month. Vernon from the Callander and West Perthshire U3A Astronomy group shares what to look out for this month. 

It is always helpful to have a star chart to follow when navigating and observing the heavens.  A free star chart which also contains lots of additional observational notes is published monthly by Skymaps. Simply go to skymaps.com and scroll down to ‘Download the latest issue’. From here you will can download the northern hemisphere version and save it.  This is then best printed double sided to an A4 sheet. It is worth noting that planets do not appear on skymaps. In this note of astronomical events I have only included items that can be seen either with the naked eye or with a pair of binoculars.

Iridium Flares

With the nights now dark and long, and the cold temperatures yet to kick-in there is plenty of time to stargaze and observe the brighter stars, constellations, Moon and Planets.  It is starting at this time of year that we sometimes see a bright flash, fireball or a shooting star, particularly in October, however, if it was more of a glint than a fireball, there is a good chance that what you saw was an Iridium flare.  There are over 60 members of the Iridium constellation of satellite phone orbiters and they are of particular interest to satellite-hunting stargazers because there odd shape means they catch the Sun’s rays in a peculiar, but predictable way, which creates a momentary flare that can be as bright as a planet. The Heavens Above website is the place to go if you want to witness an Iridium flare.  The site gives exact times and a star chart customised to your exact location.  These flares are only momentary but are fascinating none the less.

Looking South

The Great Square of Pegasus dominates the southern sky.  This is framed by the two chains of stars that form the constellation of Pisces, together with the star Alrescha (alpha Piscium) which joins the two chains together.  Also, clearly visible is the constellation of Cetus, below Pegasus and Pisces.  Aquarius is to the east and those with a high vantage point and low horizon may see Piscis Austrinus.

The main band of the Milky Way runs downwards from the Zenith (the point in the sky directly above you) due west through Cygnus, Vulpecula, Sagitta and Aquilla to the western horizon.  Delphinus and the small constellation Equuleus lie between the Milky Way and Pegasus.  The small constellation of Triangulum and the zodiacal constellation of Aries are clear to observe high I the southeast.  Perseus is high in the east and Pleiades and Taurus are above the horizon with Orion chasing in before dawn.  A sure sign that winter is approaching.

Looking North

Ursa Major is sitting just above the horizon while overhead are the constellations of Cepheus, Cassiopeia and Perseus, with the Milky Way running between Cepheus and Cassiopeia at the zenith.  Auriga is clearly visible in the east as is Taurus with Pleiades, Hyades and the orange star Aldebaran.  In addition, Orion and Gemini are making an appearance.  The three stars of the Summer Triangle, Altair, Deneb and Vega, are still clearly visible with Altair beginning to approach the horizon in the west.

Meteors

The Orionids are the major meteor shower active in October.  Like the Eta Aquariid shower, the Orionids are associated with Comet 1P/Halley.  During this second passing of the stream of particles from the comet, slightly fewer meteors are seen than in May, but the conditions are mare favourable for us Northern observers.  Both showers have very fast meteors leaving persistent trains making them quite spectacular.  The Orionid maximum is quoted as 21st-22nd October but there is a broad maximum lasting around a week from 20th-27th  October.

A faint shower of the Southern Taurids which often has bright fireballs peaks on 10th-11th October.  Around the 20th another shower, the Northern Taurids begin to show activity and peaks in early November.  The parent comet for both Taurid showers is Comet 2P/Encke.

The Planets

Mercury, Venus, Mars, Saturn and Jupiter make appearances during the month.  See below for times and locations.

Nights of interest

Some of the objects described below are expressed in degrees from the Moon.  This is far less complicated to measure than you might think. To measure 10 degrees, hold your hand up towards the sky at arm’s length and turn your hand up so that it obscures part of your view.  The width of your hand is 10 degrees and holding just one finger is two degrees.

1st – Full Moon, Harvest Moon, closest to the autumn equinox.
1st – Mercury at greatest eastern elongation of the year, 25.8 degrees from the Sun. Look for the planet low in the western sky just after sunset.
1st Oct –6th Nov – Orionid meteor shower – peaking around 21-22nd Oct.
3rd – 04.30hrs Venus appears next to Regulus as it rises in the East.
3rd – 06.00hrs Mars close to the Moon (0.7degrees) low in WSW
10th-11th – Southern Taurid meteor shower
13th – Mars will be at its closest approach to Earth and fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long.
16th – New Moon
20th – Northern Taurid meteor shower begins to show activity.
31st – Full Moon, Blue Moon. This rare calendar event occurs every few months, giving rise to the term “once in a Blue Moon.”