The Night Sky in August 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 August

New Moon Wednesday 23	First quarter Wednesday 2	Full Moon Wednesday 9	Last quarter Wednesday 16

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

 

Monthly Highlights

The summer holidays are upon us and you may well be heading for the coast or camping in the countryside. Both may give you a chance to get away from the glare of streetlights to see the full beauty of the night sky once the Sun has set over the western horizon. As the month moves on, sunset will get earlier as we head slowly towards Autumn. Come the end of August the Sun will disappear just before 8pm, so there may be a good chance of spotting one of the following monthly highlights:

August 12th - Perseid Meteor Shower

During the year, meteor showers provide us with a better chance of spotting a meteor or 'shooting star'. Meteors are usually small pieces of rock or dust that enter and burn up in the Earth's atmosphere, creating bright trails across the night sky. The most active period of the shower will occur on the nights of the 12th and 13th of August, although the glare from the Moon may prevent you from seeing some of the dimmer meteors.

The origin or radiant of the meteor shower, as shown on the above skymap, marks the point where the meteors are expected to start from and then trail out in all directions from that radiant. The meteors will last no more than a few tenths of a second, so you have to concentrate .... blink and you'll miss them. That said, the Perseids is expected to be the best meteor shower this year.

So what causes Meteor Showers?

At certain times of the year, Earth passes through a trail of dust and debris that is left by a passing comet. In the case of the Perseid meteor shower the culprit is Comet Swift-Tuttle, which was first spotted passing through Earth's orbital path back in 1862 - thankfully at a point in the year when Earth was elsewhere. The comet is now known to orbit the Sun every 120 years and is predicted to make a very close fly-by of Earth in the year 2126 and potentially pose a collision risk in the year 3044. Something that future generations may have to worry about.

August 27th - Venus-Saturn Conjunction

Even though the planets travel along a path known as the ecliptic - well fairly close to it anyway - it is not often that they almost touch in the night sky. One of those times will occur at around midnight on the 27th August, when Saturn and Venus come within a few arcminutes of each other.

Sadly, we won't see the point of closest approach, as it will take place well below the horizon. However, we can see them still close to each other when they appear above the east-northeastern horizon around 4.30 am, some 90 minutes before sunrise. If you are feeling particularly alert at that time in the morning, why not see if you can capture an image of the event on your camera and send it in to us - make sure you do so before the Sun comes up.

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 the whole month as a morning object, rising initially in the east-northeast a good 90 minutes before the Sun. On August 7th it will reach its greatest western elongation (separation from the Sun) and then slowly position itself to pass behind the Sun on the first day of September. Unfortunately, because Mercury is always low when the Sun is about, it is one of those objects that the Liverpool Telescope cannot safely observe. Venus Venus continues to move away from us on the inside track and will remain a morning object and brightest planet for most of 2006, finally passing behind the Sun in late October. Those wanting to spot Venus in August will have to get up early and look above the eastern horizon during the two hours before sunrise. By the end of the month this becomes just 90 minutes as Venus's anugular separation from the Sun decreases. Don't forget to look for the Venus-Saturn conjunction on the 27th August - see monthly highlights above. Also, why not use the electric orrery to see how Venus and Mercury will remain morning objects during the month. Mars Mars remains visible throughout the month but continues to diminish in size and brightness as Earth moves away. It can be found above the western horizon shortly after sunset and sets in the west-northwest around 9pm. Mars continues to move around behind the Sun and will reach superior conjunction (other side of the Sun to Earth) around mid-October. Now only slightly brighter than stars around it, Mars will be noticeable only by its slightly red hue and the fact that it moves from night to night. Sadly it will be nearly a year before we get detailed images again. Jupiter Jupiter remains the best target to observe after passing opposition (the other side of Earth to the Sun) in early May, although it is decreasing in both size and brightness as we start to move away from it on our inside track. By mid-month, this giant of a gas planet can be found low above the south-western horizon just after sunset and itself sets around 11pm. Why not use Go Observing to obtain an image of Jupiter and see if you can capture its elusive red spot or other storm cloud features on its surface. Saturn Saturn starts the month lost in the solar glare as it starts to pass behind the Sun, reaching superior conjunction (behind the Sun) on the 7th August. It re-emerges in the following days as a morning object and by the month's end will be rising over the western horizon a good 60 minutes before the Sun. We have to wait until the end of this year to get decent images of Saturn again. Why not try using the electric orrery to see how Saturn passes behind the Sun during August.

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 Serpens, the Serpent, which stretches above the south to southwestern horizon after sunset. Serpens is the only contellation that is split into two parts, Sepens Caput (serpent's head) and Serpens Cauda (serpent's tail). These two distinct parts are divided by the constellation of Ophiuchus, the serpent holder.

Try using the stars of the Summer Triangle to locate both parts of the serpent.

August Night Sky

Although the stars of Serpens are not the brightest in the night sky, the constellation is home to some of the most beautiful objects in the Universe. One of these is known as M16, the Eagle Nebula, which is a large cloud of gas and dust from which stars are in the process of forming - in effect the nebula is a stellar nursery.

Colour image of M16, taken by the Liverpool Telescope

The above image was obtained by observing M16 through several different colour filters on the Liverpool Telescope. These were later combined to form this lovely near-colour image of the nebula. Although the observing conditions were not ideal on the 21st July 2006, this picture does show the kind of detail you can get using the Go Observing interface to request images from the Liverpool Telescope.

Mythology: Serpens

Serpens Constellation

As we mentioned, the Serpens constellation is connected physically with Ophiuchus, the serpent holder. Ophiuchus was a famous healer and the serpent is depicted as coiled around his waist. Serpens Caput is the head of the serpent, while Serpens Cauda is the tail.

According to mythology, Asclepius (Ophiuchus) was considered the founder of medicine and learned the secrets of life and death from a serpent after it brought herbs to heal another serpent. In order to avoid the human race becoming immortal under Asclepius's care, Hades (God of the Underworld) had Zeus kill him with a bolt of lightning, whereupon Zeus placed him in the heavens to honour his good works. Since ancient times the image of a snake entwined on a staff (the Caduceus) has been the symbol of medicine.