The Night Sky in October 2006

Looking at the night sky with the naked eye or using a small telescope can be fascinating, so each month these notes keep you up-to-date with unfolding events.

Maps of the current night sky can be seen by clicking HERE

Phases of the Moon in October

New Moon Sunday 22	First quarter Sunday 29	Full Moon Saturday 7	Last quarter Saturday 14

Click HERE to see the phase of the Moon on each day of the month.

 

Monthly Highlights

With the Autumnal Equinox (September 23rd) well behind us, the nights are closing in thick and fast. If you want to know when the sun will set or rise where you are, why not try using the NSO's calculator to do all the hard maths for you. Don't forget that the clocks go back an hour at 2am on Sunday 29th October. The good news is that we all get an extra hour in bed. The bad news is that it will get darker much earlier in the evening, but at least we don't have to stay up too late in the evening to get a good look at the night sky, and possibly spot one of the following monthly highlights:

height=250 border=20 align=right alt="Harvest Moon"> October 7th - Harvest Moon

Look out for the Harvest Moon on the 7th. This is traditionally the name given to the full moon that is closest to the autumnal equinox. It was so named because it allowed the harvesting of summer crops to continue well on into the night. In the Autumn, full moons tend to rise in the evening, and because of the low arc the Moon appears to make through the night sky, it appears bigger and brighter than at other times of the year.

If you are captivated by the beauty of the full moon, then you may well be interested in the Moonsaic project we are running throughout November 2006. Essentially, the project is aimed at Keystage 2 to 3 students and involves creating a large mosaic of the Moon using images taken recently by the Liverpool Telescope.

Click here for more about the Moonsaic Project.

October 21st - Peak of Orionid Metor Shower

At certain times of the year, the Earth passes through a trail of dust and debris that was left by a passing comet many years ago. When it does so, we see an increase in the number of meteors or shooting stars as debris enters and burns up in the Earth's atmosphere due to friction. When these events occur they are known as meteor showers. The cause of the Orionids is actually the most famous of comets, Halley's Comet, which orbits the Sun every 76 years and has been seen and recorded by astronomers since 240 BC, making its last appearence in 1986.

The left-over comet trail is quite extensive; so although there's an increase in the number of meteors from the 15th October onwards, the peak of the Orionid meteor shower occurs overnight on the 21st October before reducing again toward the 29th. During the peak, you can expect to see around 20 meteors per hour. These will appear to originate close to the star Betelgeuse in the constellation of Orion. Because the Moon is close to its New phase, the resulting dark sky will provide excellent conditions for seeing orionid meteors, with the best time predicted to be in the few hours before dawn.

The Planets

Click HERE and start the Electric Orrery to see where all the planets are today in relation to each other.

Mercury Mercury spends all month as an evening object, reaching greatest elongation (i.e. seperation from the Sun) on October 17th. Throughout the period, it can be found skirting above the south-western horizon shortly after sunset. Although Mercury technically sets 30 minutes after the Sun, unless you are observing across the flatness of the sea, the chances are it will be too low to pick out. Venus Venus starts the month as a morning object, but is so close to the Sun that it will be lost in the solar glare as it continues to move slowly behind the Sun. It finally reaches superior conjunction (other side of the Sun to Earth) on the 27th October, before becoming an evening object for the rest of the year. Why not use the electric orrery to see how Venus moves behind the Sun (when viewed from Earth) during October. Mars Mars is another planet that will pass behind the Sun during October. Because Earth orbits closer to the Sun, we travel more quickly than Mars and will therefore be catching it up. For this reason Mars will start October as an evening object that remains for just 10 minutes after sunset. As such it will be lost in the glow of evening twilight. Mars passes conjunction (other side of Sun to Earth) on 23rd October and will slowly emerge as a morning object during November. Sadly we will have to wait until late summer next year before we can get decent images of Mars again. Jupiter Jupiter is now too low in the evening sky for the Liverpol Telescope to obtain an image. During October it remains barely visible above the west-southwestern horizon for no more than an hour following sunset. As we continue to catch it up on our faster inside orbit, Jupiter will appear to move closer to the Sun, and will reach conjunction (far side of the Sun) in late November. Try using the electric orrery to see how the Earth and Jupiter are on opposite sides of the Sun at the moment. Saturn Saturn is currently the only planet we can get decent images of using Go Observing. At the start of the month, Saturn rises in the east around 2.30am, and climbs high above the south-eastern horizon during the four hours before sunrise. As the month goes on this rise-time moves earlier into the evening, making Saturn an increasingly decent object to observe. Why not have a go at capturing Saturn and its ring system using the Liverpool Telescope.

Constellation of the month

Each month, a new constellation is highlighted for you to identify in the night sky.

This month we will be looking for the constellation of Pegasus, the winged horse of the gods, which can be seen high in the southern sky close to midnight. The easiest way to find Pegasus is by looking for four bright stars that make up the shape of a box, known as the Great Square of Pegasus.

October Night Sky

One of the more notable objects within the constellation is the globular cluster known as M15. A globular cluster, as the name suggests, is a region of space where many thousands of stars have come together to form a cluster. Globular clusters are generally associated with some of the oldest stars in our galaxy, and it's thought that these stars have been around since the early days of the Universe. The clusters tend to live outside the main arms of our galaxy.

Stunning image of the M15 Globular Cluster in Pegasus ©NOAO

These ancient stellar relics are typically cooler and redder than our own Sun, and are expected to live several billion years longer. Because the stars are so densely packed, the strong gravitational forces between member stars is expected to clear (hoover-up) the cluster of any gas, dust and planets. Whereas once the stars in the cluster were more spread out, over time, gravity has gradually pulled them into the tight oval we see today.

Mythology: Pegasus

Pegasus was brought to Mount Helicon by Bellerophon and with one kick of his hoof, he caused the spring of Hippocrene to flow. Hippocrene is said to be the source of inspiration to poets. Bellerophon, who slayed the hideous beast Chimaera, became so headstrong that he ordered Pegasus to fly him up to Mount Olympus, the home of the gods. This impudence angered Zeus, who sent an insect to sting the winged horse, who bucked Bellerophon off its back. Needless to say, Bellerophon did not survive the fall to Earth. Pegasus went on to greatness, however, as the "Thundering Horse of Jove" who carried lightning bolts for Zeus.