The October 2015 Night Sky

Welcome to October! The nights are now longer and the stars come out earlier. Yes it may be getting close to winter, but who doesn’t like autumn? October is full of exciting events, and one event that we are looking forward to here in the Planetarium is World Space Week. It runs from 4 October through to 10 October.

Draconids Meteor Shower: Looking North towards the constellation of Draco the Dragon, you will see the meteors radiate from the area circled. 8th/9th October, 12:00am. (Image credit: Heather Taylor, Stellarium)

Is there anything better that could happen during World Space Week than a meteor shower? On 8 and 9 October, the night sky will be privy to the Draconids Meteor Shower. It is a pretty minor meteor shower, producing roughly 10 meteors per hour, but it’s a meteor shower nonetheless. In recent years there have been periods where the Draconids have had a storm, and many meteors have been viewed, however no one is expecting that this year. The meteors are produced by small grains of dust left behind by the comet 21P Giacobini-Zinner. This comet was first discovered in 1900 by Michel Giacobini, in France. He first observed the comet in the constellation of Aquarius. The comet was recovered two passages later by Ernst Zinner, from Germany, in October 1913. The meteors will radiate from the constellation of Draco the Dragon. With no strong moonlight in the sky to hamper the meteors, why not try venturing out into the countryside, find a nice dark piece of sky and try counting how many meteors you can see.

Uranus opposition: Looking east on 11 October, Uranus will be at opposition and you will need a telescope to view it. This planet is 2.5 billion kilometres away so we’re seeing the planet as it was more than two hours ago. (Image credit: Heather Taylor, Stellarium)

Uranus will be at opposition on 11th October. The blue-green planet will be at its closest approach to the Earth, and its face will be illuminated by the Sun. This will be the best time to view Uranus, however don’t expect to see it with the naked eye, as it is roughly 2.5 billion km (16.7au) from the Earth. You will need a powerful telescope to be able to view Uranus. This planet is the only planet in our solar system to be tilted on its side, with an axial tilt of about 98 degrees. It has a surface temperature of -197oC and was first discovered by William Herschel in 1781. A quirky fact about the finding of Uranus is that upon discovery, Herschel wanted to name the planet “Georgian Sidus,” after King George III. Thank goodness Johann Bode (see also Bode’s Law, or Titius-Bode Law) came along and suggested the name Uranus, after the Greek deity Ouranos. Would you have really wanted a planet being called George?

On 13th October there will be a new moon, so the night sky will be devoid of the light of the moon. This will be a great time to observe some of the wonderful celestial objects that we can see in the night sky. What are our recommendations this month?
The Andromeda Galaxy, the sister galaxy of our own Milky Way, can be viewed at this time of the year. With no moon light in the sky to hinder it, you will stand a chance of being able to view this galaxy, but be warned, it can be tricky to find on your first attempt, but once you know where it is, it becomes a little easier.

Andromeda Galaxy: False colour image of the Andromeda galaxy, the biggest galaxy in our local group. (Image credit: NASA & JPL/Caltech)

The Andromeda Galaxy, or M31, is a spiral galaxy, and is approximately 260,000 light years in diameter. The Andromeda Galaxy is the biggest galaxy in our Local Group of galaxies. Despite earlier findings that suggested that the Milky Way contains more dark matter and could be the most massive in the grouping, in 2006 observations by the Spitzer Space Telescope revealed that Andromeda contains one trillion (10¹²) stars: at least twice the number of stars in our home galaxy, which is assessed to be 200–400 billion. In 4.5 billion years’ time, the Andromeda galaxy will collide with the Milky Way, and will form a giant elliptical galaxy. This galaxy is approaching the Milky Way at approximately 100-140 kilometres per second.

On 13th October, if you look south at 10:30pm, you will be able to see the Great Square of Pegasus, and in the image you will see the Andromeda Galaxy highlighted. You will need a dark site to capture the 2.5 million year old light from this great spiral galaxy with your unaided eyes – but it can be done! (Image credit: Heather Taylor, Stellarium)

Another thing to look out for on the night of the new moon is the Great Square of Pegasus. The Great Square is the landmark asterism in the autumn night sky, just like the Summer Triangle is for the summer night sky. It is this asterism that will help you to locate the Andromeda Galaxy. The top left star of the square, known as Alpheratz, actually belongs to the constellation of Andromeda. The arm that extends out of this constellation is the best marker for finding the Andromeda Galaxy. You will find it sits just to the right of the tip of the arm.
The Great Square makes the belly of the majestic mythical creature Pegasus, the winged horse. Pegasus is linked to some of the other constellations in the night sky, and they tell a mythical tale. In my August Night Sky blog article, I talked about the story of Cassiopeia the Queen and Cepheus the King. Their kingdom was being ravaged by the sea monster Cetus, and they had tied their daughter Andromeda to a rock as a sacrifice to the creature. The hero of the story was Perseus, so let’s find out a bit more about him.

The Great Square of Pegasus makes the belly of the much larger constellation of Pegasus the winged horse from Greek mythology. Located in the south at this time of the year, the best time to go out to view him is later in the evening. (Image credit: Heather Taylor, Stellarium)

Perseus was the son of Zeus and the mortal woman Danae. Danae was the daughter of King Acricius of Argos. He had learned from an oracle that the son of Zeus and his daughter would eventually kill him, so he locked his daughter away in a bronze chamber. Upon finding out his daughter had given birth to a son, he locked Danae and baby Perseus in a wooden box and threw them into the ocean. Somehow, the pair survived and found their way to the island of Serifos, where the fisherman Dictys raised Perseus into manhood. Dictys’ brother was the King of the Island, and he fell in love with the beautiful Danae. Not wanting his mother to be harmed in any way by the lecherous king, Perseus protected his mother from his advances. As a way to disgrace Perseus, the king held a banquet, and requested that all the guests bring him the gift of a horse. Not having the money to get a horse, Perseus told the King he would get him whatever he wanted. The king took up this offer and told Perseus to get him the head of the gorgon Medusa.

Perseus (level 7 fighter with +2 Short Sword, Masterwork Leather Armour and +1AC Light Shield) carrying the head of his conquered foe, Medusa the Gorgon (Monstrous Humanoid, 33hp). You can find this constellation in the north east of the night sky. Image credit: Heather Taylor, Stellarium

Perseus went on his journey to get the head of this monster. Medusa had once been a beautiful woman, but after getting on the wrong side of the god Poseidon and goddess Athena, she was cursed, and her hair was turned into snakes, and anyone she gazed upon would turn to stone. With some help from the gods, Perseus went forth into the lair of the gorgon. Using a mirrored shield to deflect the gorgon’s gaze, he was able to cut off her head. It is said that from the body of Medusa, sprung Pegasus, as Pegasus was the result of a union between Poseidon and Medusa. Using Pegasus, Perseus was able to escape the Gorgon’s hideout.
On his way back to the island of Serifos, Perseus noticed Andromeda strapped to the rock as a sacrifice to Cetus. He saved her and went on to marry her, even though she was promised to another. At their wedding, Andromeda’s suitor stepped forth to try and claim her, but Perseus used the head of Medusa to turn him to stone. Cassiopeia and Cepheus also looked at the head of Medusa at this time and were also turned into stone.

Looking east on 22nd October at after midnight, you will be able to see the radiation point of the Orionids Meteor Shower at the constellation of Orion. The radiant area is highlighted here. (Image Credit: Heather Taylor, Stellarium)

If one meteor shower wasn’t enough for you this month, then prepare yourselves for the Orionids Meteor Shower on 21st and 22nd October. The Orionids is an average shower, so it is a little better than the earlier Draconids shower of this month. The Orionids can produce up to 20 meteors per hour when at its peak. These meteors are produced by grains of dust left behind by a comet you’ve probably heard of…Halley’s Comet. Arguably one of the most famous comets in all of history, Halley’s Comet periodically returns into the vicinity every 75 years. The last time we got to gaze upon it was in 1986, and we’re not expecting to see it again until 2061. These meteors will radiate from the constellation of Orion, but can appear anywhere in the night sky, so make sure you step outside and have a look into the night sky.

Looking South East in the early morning of October 28th, you will see the conjunction of Venus, Mars and Jupiter in the sky. A wonderful, and fascinating occurrence. (Image Credit: Heather Taylor, Stellarium)

On 26 October we will get to see a conjunction on Venus and Jupiter. Doesn’t this sound familiar? Well the last time we got to see this conjunction was back in June at the end of the month. The conjunction was visible in the early night time sky, and this next conjunction on 26 October, will be visible in the early morning sky. Venus and Jupiter will appear very close together in the sky, within 1 degree of each other to be precise. If you would like to see this event, you have to be an early bird and get up before dawn to catch a glimpse.

The full moon will be in the sky again on 27 October. If you are thinking about looking for any deep sky objects on this night, you’d better think again, as the sky will be flooded with the light of the moon. In Native American culture this particular full moon was known as the Hunters Moon. At this time of the year it is said that deer and other big game animals are fat and ready for eating, so this is the time for the hunters to target their prey.

As if October wasn’t full enough already of great things to see in the night sky, we also have another conjunction, this time between Venus, Jupiter and Mars on 28th October. It will be quite the wonderful sight to see, and will be visible with the naked eye. You could also view the spectacle with a pair of binoculars or a telescope if you wanted to get a closer look at these wonderful planets. The best time to see this will be in the early morning just before dawn, so like the previous conjunction on 26th October, if you’re an early bird, you stand a chance of seeing this.

Finally, after all that excitement, don’t forget to turn your clocks back this month too! You can turn back your clock by one hour on the last Sunday of October, and you will get that joyous extra hour in bed!

(Article by Heather Taylor, Education Support Officer)