Monday 28th August to Sunday 3rd September 2023

Thursday 31st August sees the second Full Moon of the month.  When this occurs, the second one is commonly called a Blue Moon, but this is technically incorrect.  The mis-interpretation of the definition first appeared in print back in 1946 and it stuck because it is easier to understand.  Officially, a Blue Moon is the third full moon in a season of four.  Let's just stay with the first definition!


This Full Moon occurs at perigee again, when the Moon is closest to the Earth in its orbit around us and looks slightly brighter and larger than at other times, so it is therefore called a Super Blue Moon.


On 31st, just as it's getting dark, the Moon will have risen above the horizon towards the east, with Saturn shining to the right of it and a little higher in the sky.


If you stay up to around 11pm, then the Moon will appear more towards the south east and Jupiter will have risen to the left of it in the east.


Ironically, full moons at this time of year tend to be at a relatively low altitude so they appear more orange than blue!  The light being reflected from the Moon's surface passes through more of our atmosphere and this scatters the blue wavelengths.  If you catch the Moon rising above the horizon, it sometimes looks huge.  This is known as "Moon Illusion" and is simply a trick that your brain plays on you - although the effect has been known about for thousands of years, we still don't understand why!  It has nothing to do with the Moon being at perigee.


Moon Illusion image courtesy of NASA



Monday 21st to Sunday 27th August 2023
Last week I talked about the astronomical term "conjunction" where two celestial objects appear to be close together.  Another term called "opposition"  occurs when two bodies are in opposite parts of the sky.

On Sunday 27th, Saturn reaches opposition to the Sun, so it is well-placed for observing with a magnitude of around +0.3 and the planet reaches a maximum elevation of 25 degrees above the horizon.


If you venture outside any evening next week and look towards the south around midnight, Saturn will be approaching this maximum height in the sky. 


As light passes through our atmosphere, it becomes distorted which can spoil the view through a telescope with high magnification eyepieces and it is also why stars appear to twinkle.  Astronomers always prefer to observe objects when they are at high elevations and the light from them is passing through less atmosphere, so next week is an ideal opportunity to point your telescope towards Saturn and look at those amazing rings circling around it!


The rings are made from countless particles ranging in size from a few micro-meters to several meters in diameter.  They are mainly made from water ice and to this day, space scientists cannot agree how they were originally formed.

The first person to observe them was Galileo back in 1610, but with his basic telescope, he was unable to resolve any detail.  A much better view was provided by the Voyager 2 space probe in 1981.
Image courtesy of NASA



Monday 14th to Sunday 20th August 2023

Mercury and Venus are "inferior planets".  Now that sounds like I'm being a bit nasty, but in astronomical terms it's nothing derogatory at all.  It simply means that those planets orbit around the Sun inside our own orbit or in other words, they are closer to the Sun than us and we are classed as the "superior planet".


To a Martian, Mars would be the superior planet and the Earth would be classed as another inferior planet!


At the beginning of next week, Venus will have just passed an "inferior conjunction" with the Sun.  An astronomical conjunction occurs when two objects appear close together, but of course this is only from the observer's perspective which is two dimensional as you have no depth perception when looking at something in the distance - in reality the objects will still be far away from each other when you think three dimensionally.

An inferior conjunction takes place when the inferior planet is in a straight line directly between the superior planet and the Sun.
Conjunction diagram courtesy of

As they orbit around the Sun, inferior planets also show different phases, just like our own Moon.  If you were to try observing Venus at its inferior conjunction, you would see a thin phase of 0.1%, like a very, very thin crescent, but please don't be tempted to try it as you would be looking directly towards the Sun and this would cause instant and permanent blindness.  The experiment would need very specialised equipment and a camera rather than an eyepiece!



Monday 7th to Sunday 13th August 2023

It's worth staying up to around 2am on the early morning of Wednesday 9th as there will be a nice treat for the naked eye - no telescope necessary.  Look towards the east and you will see three targets - running left to right - the Pleiades open cluster of stars, a waning Crescent Moon and Jupiter.


The Pleiades is at the top of the constellation of Taurus.  If you really feel the urge to dig out your telescope, aim it that direction and locate the bright star Aldebaran in Taurus.  To the right of Aldebaran will be the Hyades open cluster.


If you'd prefer an activity earlier in the evening, look high up towards the south east after dark anytime next week and find the constellation of Cygnus, the "Swan".  Below the tail of Cygnus will be two small constellations called Vulpecula and Sagitta.  When lines are drawn to show the shapes of constellations, Vulpecula looks like a straight line and Sagitta looks like an arrow.


My reason for sending you towards these two unremarkable constellations is that between them you will find an asterism or recognisable pattern of stars known as the "Coat Hanger".  It will take a bit of looking for and will actually appear to be upside down.


The asterism consists of ten main stars and is officially known as "Brocchi's Cluster".  This is a bit of a misnomer though, as the stars are not thought to be gravitationally tied to each other, so technically they are not a cluster!  With the naked eye, the asterism will only look like a faint patch of light - binoculars or a small telescope will be needed to resolve the detail.  Just need some clear sky to be able to do it!



Monday 31st July to Sunday 6th August 2023

On the evening of Tuesday 1st August, we have a Full Moon.  At 10pm, our celestial neighbour will have just risen above the horizon towards the south east.


Nothing out there in space is a perfect circle and the Moon's orbit around us every 27 days is slightly elliptical or "egg shaped".  The point where the Moon gets closest to us is known as "Perigee" and at that time it is about 225,000 miles away.  The opposite point, when the Moon is furthest from us is called "Apogee" and then the Moon is about 251,000 miles from us.


The Full Moon on 1st happens to occur very close to perigee which means that it will appear to be 14% larger and 25% brighter than a Full Moon at apogee.  This is referred to as being a "Supermoon".  August is also unusual in that there will be two full moons in the same month, with another on 31st August.


Now I was never that good at maths, but if the Moon takes 27 days to orbit around us, why is it a few days longer than that between the full moons?

While the Moon has been orbiting around us, we have been travelling in our orbit around the Sun, so all the angles will have changed and the Moon will need to travel a bit further before the sunlight falling on it fully illuminates the near side again.



Monday 24th to Sunday 30th July 2023

If you venture outside around 2am any day next week and look towards the east, Jupiter will have risen above the horizon.  To the left of Jupiter you will find the familiar shape of the Pleiades open cluster of stars.

Half way between the two is Uranus - not a planet you can see with the naked eye as it currently has a magnitude of around +6.0 so you'll need to dig out those binoculars or a small telescope. 

For those of you preferring not to stay up quite so late, try looking towards the south west around 11pm on Thursday 27th and you will see a slightly gibbous-shaped Moon.

The 27th is the optimum evening to spot the clair-obscur effect that I've mentioned before, known as the Jewelled Handle.  It appears as an arc of light near the northern sunlight terminator.
At the same time, look to the left of the Moon and have a go at spotting the red supergiant star Antares.

With a magnitude of around +1.0 it is one of the brightest stars in the night sky and one of the largest stars that can be seen with the naked eye.  Its mass is about twelve times that of our Sun.  If we stuck Antares in the middle of our Solar System, it would stretch out as far as Jupiter and consume all the rocky planets of our Inner Solar System!


Antares is actually a binary star - you will only see the red supergiant, but there is also a smaller, magnitude +5.5 dwarf star beside it.



Monday 17th to Sunday 23rd July 2023

It's time to go hunting for a minor planet in the Asteroid Belt.


Last week I suggested looking towards the east to see Jupiter and the bright star Capella.  Look east again at around 3am on Tuesday 18th and you will have a similar view, with the Pleiades open cluster of stars sitting about half way between Jupiter and Capella.  Down from the Pleiades and quite close to the horizon will be the bright star Aldebaran.

Our target, the minor planet (4) Vesta is hiding a little above and to the left of Aldebaran.  It will only have a magnitude of around +8.3 so you will definitely need a small telescope to be able to spot it.

(4) Vesta is the second-largest minor planet in the Asteroid Belt (second only to Ceres) with a mean diameter of 525Km.  It is also the brightest object in the belt.  The asteroid is rocky and made from the same materials that formed the planets of the inner Solar System billions of years ago, but how do we know this?


Vesta is covered in impact craters.  Around 1 - 2 billion years ago, numerous fragments were ejected after several collisions and some of this debris made its way to Earth, landing as meteorites for scientists to subsequently study.


Interest is this little rocky fella has been so great that the NASA Dawn spacecraft spent a year orbiting around it in 2011 before continuing its main mission towards Ceres.




Monday 10th to Sunday 16th July 2023

If you look towards the east early in the morning on Wednesday 12th, say around 1.30am, a 29%-lit Crescent Moon will have just risen above the horizon, with planet Jupiter immediately to the right of it shining at a magnitude of -2.1


Taking in a wider view, Saturn will be located towards the south east and the bright star Capella will be towards the north east.


Capella is actually the sixth brightest star in the night sky and the alpha star in the constellation of Auriga.  Although it appears to be a single star to the naked eye, Capella is a quadruple star system comprising two bright yellow giant stars that are about two and a half times the size of our Sun and two much fainter red dwarf stars.  The stars are relatively close to us - around 43 light years away.


If you want to see the whole of Auriga, you will have to wait until around 3am when all its stars will have all risen above the horizon.  Immediately to the right of Auriga and very close to the horizon will be the constellation of Taurus, with the easily-identifiable Pleiades open cluster of stars just above Taurus.


There are a number of really good opportunities to spot the International Space Station next week.  Monday 10th at 1.21am, Tuesday 11th at 2.10am, Wednesday 12th at 1.22am, Thursday 13th at 12.34am and again on the Thursday at 2.11am.


In all these cases, the ISS will appear towards the west and spend around 7 minutes passing almost directly overhead before disappearing to the east.



Monday 3rd to Sunday 9th July 2023

Lately I've been encouraging everyone to look towards the west just as it's getting dark to see Venus and Mars.  Well how about giving our old friends, the gas giants Saturn and Jupiter, a chance?  Unfortunately this does mean either a late night or early morning though!


If you look towards the south east around 2am on Friday 7th, Saturn will be sat just above an 81%-lit waning Gibbous Moon.  If at the same time you look further east, Jupiter will have just risen above the horizon.

If you prefer slightly more sociable hours, there is still chance to catch a glimpse of a very bright Venus setting towards the west just as it's getting dark. 

Remember that the whole month of July is also a good opportunity to observe Noctilucent clouds for up to a couple of hours after sunset.  These "night-shining" clouds are caused by sunlight reflecting off layers of ice crystals in the upper atmosphere and are notoriously difficult to predict.


There are three good opportunities to spot the International Space Station next week.  Monday 3rd at 3.45am, Wednesday 5th at 3.44am and Thursday 6th at 2.56am.  In all three cases, the ISS will appear towards the west and spend around 7 minutes passing almost directly overhead before disappearing to the east.


If you have never observed the ISS before, it appears to look like a star that is eerily moving quickly against the background sky.  The space station is actually travelling at an incredible 7.5km/s or approximately 17,500mph.  It has to travel that fast to remain in orbit and not fall back to Earth!