Newbury Weeky News monthly column

Every month, our Vice Chair Tony Hersh writes a popular column for the Newbury Weekly News. From now on, these can be found on this page and also within the pages of Pegasus, the new society newsletter

OCTOBER 2024

October is the month of the Orionid meteor shower, where the dust left from Halley’s comet vapourises in the Earth’s atmosphere.  The meteors will appear to come from an area just above the Constellation of Orion, peaking on 21st and 22nd and we will have a crescent Moon so have a better chance than usual of seeing a meteor every few minutes. 

Almost directly south, halfway up from the horizon, the square of Pegasus should be clear.  If you can see more than 5 stars within the square the sky is very clear and good for observing!  The square can be used to locate the Andromeda galaxy, a faint blur between the Great Square and Cassiopeia’s “W” shape.  Andromeda is a huge spiral galaxy and is the most distant object that can be seen with the naked eye (it is 2.5 million light years away). Andromeda is moving towards our Milky Way galaxy at high speed and will pass through and gravitationally interact with our galaxy in about 4.5 billion years, producing a new combined galaxy.  

Several planets are easy to spot this month.  Saturn will be just above the Moon around 8pm on 14th October, Jupiter just below the Moon after midnight on 21st and Mars just to the right of the Moon after midnight on 24th of the month.

Topic of the Month

We spend a lot of time thinking about the world around us and the universe above us but there are amazing things happening beneath our feet inside our lovely planet! 

The Earth was formed by coalescing debris and impacts from asteroids 4.5 million years ago and heavy iron sank towards the middle.  The immense gravitational pressure of Earth keeps the core molten and it’s the rotation of the core which moves electrically charged material around and creates the magnetic field that protects Earth from radiation and allows compasses to work and some animals to navigate.  The iron core is huge, nearly half the size of Mars but the rotation isn’t completely stable for reasons that aren’t completely clear.  In the 1970s scientists discovered that sometimes there are abrupt and unpredictable changes to Earth’s magnetic field and this is thought to be due to changes in how core is rotating.  Recently some areas above Earth have been discovered, like the South Atlantic Anomaly,  which have reduced field strength, meaning radiation from space isn’t so well deflected by the Earth’s magnetic field in that, affecting satellites which pass through it and creating an area astronauts have to avoid for fear of being irradiated.  Very occasionally (maybe every 800,000 years) the entire magnetic field of Earth can flip which would certainly disrupt navigation and satellites. 

Tracking changes in Earth’s magnetic field is a fairly new science so it’s difficult yet to predict what might happen and the implications. But it’s a fascinating consequence of living on a complicated planet made of a mixture of solid, liquids and gases !

SEPTEMBER 2024

There are some great Apps available to help you identify what’s in the night sky. On my iPhone you just open the App and hold it up towards the sky and it shows you what’s there and moves with you as you turn.  I find Star Walk 2 and SkyView Lite both work well. There’s also an App called Scope Nights that gives a weather forecast for nighttime and it’s remarkably accurate - it’s useful for planning when to go out and look at the night sky. Another interesting one is ISS Transit Finder which tells you when the ISS will be crossing the sky above you. The ISS is the International Space Station which was launched in 1998 and has been occupied by astronauts ever since. From Earth it appears as a really quite bright dot because at around 250 miles above the Earth’s surface it’s high enough to still be in sunlight which then reflects off it. It moves fairly quickly across the night sky and disappears from view before it reaches the horizon as it passes into shadow.

If you’re looking for interesting objects in the night sky, Saturn is easy to spot this month even without an App because it will be just to the right of the Moon around 10pm on 17th September. Mars appears as a pinkish object just below the Moon at around 3am on 25th September 

Topic of the Month

Galileo famously tried to measure the speed of light by getting two volunteers to stand on hills a few miles apart with shuttered lanterns.  The idea was the first person would uncover their lantern and as soon as the second person saw it, they would then uncover their lantern.  Any delay beyond the normal reaction time would be due to the light travelling and the speed could be calculated.  Unfortunately, no difference in time could be found compared to people doing the same experiment close together.

Later, a good idea was dreamed up by a Danish astronomer Ole Roemer in 1670. He was looking at the moons of Jupiter through a newly invented telescope and found the time the moon Io took to orbit Jupiter varied at different times of the year. He realised, with an exceptional stroke of brilliance, that since both Earth and Jupiter are orbiting the Sun at different distances, at some times the Earth is closer to Io than at other times and that the discrepancy in the orbit of Io was due to a delay in light reaching Earth.  He calculated the speed of light as 220,000 kilometres per second, though possibly he was lucky to get it quite so accurate. 

Nowadays, the speed of light can be calculated with absolute accuracy using lasers emitting light of a specific frequency and using interferometry to calculate its wavelength allowing the speed to then be calculated mathematically.  In fact, the speed of light is known so precisely we use it to define distance!  One metre is defined as the distance light travels in one 299,792,458th of a second. This puts the speed of light at 299,792.458 kilometres per second with absolutely zero uncertainty.  

AUGUST 2024

August is the month of the famous Perseid meteor shower, this year peaking on the evening of 12th August and we are lucky this year because the Moon is only a quarter full so won’t be dampening the show. Meteor showers originate from comets that heat up as they near the Sun, the ice inside them turning to gas and bubbling off the surface, taking dust and rubble with it and creating the famous tail. The particles of dust and rubble then stay drifting in space, following the comets orbit, but if the Earth travels through them on its own path round the Sun they heat up as they strike our atmosphere, glowing white hot as they disintegrate and appearing as streaks of light across the sky. The comet that causes the Perseid meteors is dust and rubble left behind from Comet Swift-Tuttle that orbits the Sun every 133 years, last appearing in 1992.   If you look anywhere in the lower part of the sky towards the north (the Plough and Pegasus can both work well as areas to watch) after it gets dark you might be able to see a meteor every minute or two, weather permitting!  

Saturn is visible this month, just above the Moon around 4am on 21st August and pinkish Mars and bright Jupiter will be just to the right of the Moon on 28th.

Topic of the Month

We’re all familiar with the fact that there are rings of material surrounding the planet Saturn.   The rings are made of small rocks and ice and are kept in place by larger “shepherd” moons that have their own gravitational influence over the rings. However, when Voyager 1 and 2 spacecraft flew past the planet in 1980 and 1981, they photographed some very unexpected dark spokes in the rings.  These radial markings were found mainly in Saturn’s largest and brightest ring called the B ring. The spokes seem to appear and then disappear for years at a time and there had been no trace of them for decades until the Hubble Space Telescope recently spotted them again. What causes them is a complete mystery. Astronomers suspect they might be created by Saturn’s magnetic field interacting with the solar wind, creating an electrically charged environment that could give the smaller particles in the ring an electric charge. Electrostatic forces might then line up these charged particles and cause the spokes. But this doesn’t explain why they come and go, or other aspects such as the number of spokes created, their even spacing and how far apart from each other they are. The spokes join a long list of observations astronomers struggle to explain about Saturn, from the origin of the rings themselves to the strange and very unexpected enormous hexagon shape in the cloud cover above one of the poles of this planet.

JULY 2024

July is a good time to spot Cassiopeia, named after the vain queen of Greek mythology, who boasted about her unrivaled beauty. If you start from Ursa Major (The Plough, Saucepan or Great Bear) and follow an imaginary line joining the two stars furthest from the “handle” of the saucepan upwards you will come to the Pole star and about the same distance again see the distinctive W shape of Cassiopeia. The constellation hosts some of the most luminous stars known, including the yellow giant stars Rho Cassiopeiae and V509 Cassiopeiae and white giant 6 Cassiopeiae. Fourteen star systems in this constellation have been found to have planets orbiting them and one star —HR 8832— has at least seven planets going round it.

Planets in our Solar System are difficult to spot in a lightish sky this month, but Mars is the pinkish object just to the right of the Moon around 4am on 2nd July and just below the Moon at the same time on 30th July. Saturn is shining just to the right of the Moon around midnight on 24th July.

Topic of the Month

As if there isn’t enough to worry about in the world already, this month our topic is Gamma Ray Bursts (GRB). GRB are short lived but extremely intense beams of highly energetic gamma ray radiation travelling through space. They are created in just a few minutes and typically contain more energy than our Sun will produce in its entire 10-billion-year lifetime.  Astronomers have observed them from huge distances away because they are so bright and there are way more of them happening that we don’t see because the rays are focused into narrow beams which travel through space and only a tiny proportion happen to be travelling towards Earth. They are thought to be created when massive stars explode in a Supernova or when super dense neutron stars collide. GRB can still have a very destructive effect on Earth despite having travelled vast distances. We have all heard of the idea that dinosaurs were killed off by an asteroid hitting Earth and throwing up so much dust into the atmosphere that temperatures on Earth plummeted. But geologists have reported that nearly 400 million years before dinosaurs existed there was another ice age on Earth which seems to have killed off two thirds of all species on our planet.  One explanation is that a GRB irradiated the Earth which would have depleted the Earth’s ozone layer. If this happened, having less ozone would have allowed much more ultraviolet light from the Sun to reach the surface of Earth, irradiating and killing life on the surface of our planet. The intense gamma rays would also have turned nitrogen and oxygen in our atmosphere into nitrogen dioxide, a smog which would have blocked visible sunlight causing plants to die. Fortunately, GRB are relatively uncommon and, as mentioned above, the vast majority don’t come anywhere near our planet, but they have the potential to cause huge damage and there’s not much we can do at the moment to stop them or even spot that they are coming! 

JUNE 2024

June has the most daylight of any month with the longest day and shortest night. Although the days get shorter after Midsummer’s Day on 21st June, the thermal lag means the hottest days are still ahead of us. It’s a good time to look out for the rarely seen Noctilucent clouds: long wispy clouds with a distinctive electric blue tint which are being lit by the Sun while it’s below the horizon. These clouds are the highest of all clouds at around 80km and are often hundreds or thousands of kilometres away from the observer. The best time to look for them is towards the north, 90 mins to 2 hours after the sunset, close to the horizon.

This month the constellations are harder to pick out due to the lighter sky, but the W shape of Cassiopeia will still be visible from around 11pm.  You will find it if you follow the two stars at the end of The Plough upwards towards the next brightest star, the Pole Star. The W shape of Cassiopeia is about the same distance away from the Pole Star opposite The Plough. In mythology, Cassiopeia was a vain queen who was punished by Poseidon for her wicked ways and forced to wheel around the Pole star forever.  If you’ve never seen Spica, the brightest star in the constellation of Virgo, it will be just to the right of the Moon around 10pm on 16th June.  This star is actually one of two stars rotating around each other around 250 light years from our Sun.  

Topic of the Month

Planets orbit around stars and astronomers have discovered that the vast majority of stars do have several planets orbiting them. The common method for detecting planets orbiting distant stars is by having telescopes on Earth or in space watch distant stars and monitor their brightness. If a planet goes across the face of the star the brightness of the star drops and that’s a sure sign of a planet in orbit. With modern technology we can now find out a surprisingly large amount of information about those planets. By monitoring how much the brightness drops, and the frequency and duration of the drop in brightness, we can calculate the size of the planet, how fast it is travelling while orbiting its Sun and even its density and surface temperature. At the moment the distant planet approaches or leaves the face of its star, the sunshine from that star reaches Earth having first travelled through any atmosphere which exists around the planet.  Molecules in the planet’s atmosphere leave a spectral fingerprint in the filtered starlight and this fingerprint can be detected by a technique called Transmission Spectroscopy (TS). The new James Webb space telescope is using TS so astronomers can identify elements and molecules in atmospheres around planets light years away from us.  They have already spotted atmospheres containing hydrogen, carbon and even water.  Looking for planets which have liquid water in their atmosphere together with oxygen, ozone, methane and nitrous oxide would give us an indication that life might exist on those planets. It’s quite extraordinary that so much information can be obtained from planets billions of miles away which appear as microscopic dots in even our biggest telescopes.  

MAY 2024

This month is a good one to spot the bright star Vega in the constellation of Lyra.   Follow an imaginary line joining the two stars making up the saucepan part of Ursa Major (The Plough or Saucepan) nearest the handle right across the sky and the first really bright star is Vega. Vega is the third brightest star in our sky, after Sirius and Arcturus. It’s relatively close to us at 25 light years and, because of its relative closeness, its position in the sky changes very gradually over time. In fact, by the year 13,727 AD Vega will be due north when observed from the northern hemisphere, taking over the position of the North Star from Polaris!

This month the Eta Aquariids meteor shower peaks late in the evening of 6th May but will be displaying several days either side of that date.   These meteors come from the trail of rubble and dust that came off the rocky surface of Halley’s Comet when it last came close to the Sun.   The rubble and dust heat up in the atmosphere of Earth as Earth passes through the trail and shows as bright steaks of light in the sky. Look towards the East approaching dawn to see them. Regarding planets, Saturn will be easy to spot just above the Moon around 5am on 4th May and just to the left of the Moon around 4am on 31st May. 

Topic of the Month

Our Milky Way galaxy is like a vast pancake shaped object 100,000 light years across and containing around 200 billion stars.  One way of trying to visualise the size of our galaxy is to start by thinking about our solar system (our Sun and all the planets orbiting our Sun right out to Neptune, which is orbiting our Sun at nearly 3 billion miles). Imagine our solar system reduced to the size of a 10p piece, with the Sun in the centre and Neptune orbiting round the furthest edge. On this scale how big would you guess our Milky Way galaxy to be? A few hundred metres?   A few kilometres? The answer in fact is approximately the size of Europe!  And there are objects way further away than the size of our galaxy. The Andromeda galaxy is the furthest thing people can see with the naked eye. It’s a faint blur of light that’s actually 2.5 million light years away, 25x the distance across our galaxy.  Although most other galaxies are moving away from the Milky Way galaxy because of the expansion of the universe, Andromeda is actually moving towards our galaxy at a speed of 360,000 kilometres per hour. However, because Andromeda is so far away it won’t crash into our galaxy until it reaches us in another 3 to 4 billion years, and this crash will be very different to typical crashes.  Because stars are such vast distances away from each other, both galaxies will pass right through each other with very few stars actually hitting each other, but the effect of gravity will be to pull the two galaxies together, creating a new super galaxy formed from the merger of both original galaxies.  The merger will also bring vast clouds of gas and dust together creating the right conditions to create a huge number of new stars, so the newly merged super galaxy will look completely different from the two original galaxies.  Objects in the universe are constantly evolving and changing and enormous changes will continue to happen for billions of years.

APRIL 2024

March is a great time to spot Ursa Major (sometimes also called The Great Bear, The Plough, The Big Dipper or The Saucepan) the ‘right way up’ if you look overhead at night.   It’s a constellation that is visible from the UK throughout the whole year although it changes it’s orientation gradually month by month.   The middle star in the handle part of the Saucepan is actually two stars very close to each other, Alcor and Mizar.   These two stars used to be a test of how good your eyesight was ; if you can see two stars rather than one blob of light your eyesight is very good !    Once you can spot Ursa Major you can use it to spot other constellations.   For example following an imaginary line that connects the last two stars in the saucepan downwards leads to the constellation of Leo with its characteristic backwards question mark shape in the sky.   Planets to spot this month include Jupiter, which will be just below the Moon at 1am on 14th March. If you have a small telescope look between the Moon and Jupiter at that time to find the blue disk which is Uranus. 

Topic of The Month

Space junk consists of bits of old rocket, parts of defunct satellites, even pieces of paint and frozen fuel.   In low Earth orbit these pieces are travelling around 25,000 mph so if even small pieces of junk hit something they can do substantial damage and create more junk in the process.  Newer satellites are designed to burn up in our atmosphere, go into a parking orbit or fall into the sea at the end of their useful life but older satellites weren’t designed with this capability and so might continue to orbit and gradually disintegrate over tens of years.   Ontop of that, testing of anti satellite missiles has created tens of thousands of pieces of junk larger than 10cm and hundreds of millions of smaller pieces. These form a ‘cloud’ of debris around Earth in exactly the same orbital position desired for new satellites or space stations, making putting new satellites into orbit increasingly difficult. Larger pieces of junk can be hit by other debris, destabilising their orbit and causing them to crash to Earth in uncontrolled ways, potentially causing damage or even death on Earth if they are big enough to get through the atmosphere without completely burning up.  In 1977 a Soviet satellite crashed in Canada.  It was powered by a small nuclear reactor and the Canadians received £2 million from the Soviets for the clean up operation.  More recently, in 2022, large pieces of a spacecraft, thought to be China’s defunct Long March 5B rocket crashed near villages in Borneo though luckily no one was reported injured.  Of course the Earth’s surface is mostly water so there is a smaller chance of space junk directly hitting a populated area but the amount of junk in orbit is causing big concerns for the continuity of GPS and communication satellites and no one has figured out a way to clean up space from all this waste.

FEBRUARY 2024

This month you have the best chance of seeing a small part of the Milky Way Galaxy.  This is the Galaxy we are part of that consists of at least 100 billion stars arranged in a massive spiral shape.  From our position in the Galaxy these stars appear as a faint band of light high in the night sky with the W or M shape of the Constellation of Cassiopeia right in the middle of it. You can find Cassiopeia by following an imaginary line downwards from the two stars at the end of Ursa Major (the famous saucepan shape).  Something else to look out for is the Constellation of Leo the Lion with its famous backward question mark.  Follow the two stars at the end of the Plough’s saucepan upwards and it should be easy to find.  Leo was one of the earliest recognized constellations, with archaeological evidence of it in 4000 BC.  In Greek mythology, Leo was the Nemean Lion which was killed by Heracles (Hercules to the Romans) during the first of his twelve labours. The Nemean Lion would take women hostages to its lair in a cave, luring warriors from nearby towns to their deaths trying to save the damsels in distress.  The Lion was impervious to any weaponry so Hercules defeated the Lion with his bare hands.  Zeus commemorated the achievement by placing the Lion in the sky for the rest of time.  Planets to look out for this month include Venus in the morning sky.  It will be just to the left of a crescent Moon around 7am on 6th February.  Jupiter dominates the evening sky, easily spottable just below the Moon around 6pm on 15th February.

Topic of The Month

It’s a huge puzzle to astronomers and physicists why we exist, in fact why any matter exists !  In the fraction of a second after the Big Bang, when the Universe was created, all our understanding of physics tells us that absolutely equal amounts of both matter and it’s opposite, antimatter, should have been created from the energy present.  It’s something predicted by Einstein’s famous E=mc2 equation which seems to work fine for all other measurements we make.  But if the prediction was right, over the millennia we would expect these particles to meet each other and reunite releasing energy again and reducing the amount of matter and antimatter in the Universe.  Not only are we not seeing this but there seems to be much more matter in existence than antimatter.  We can detect antimatter, but the amount we can find is vastly outnumbered by matter.  Nature seems to have a preference for matter rather than antimatter.  This strange preference has been observed on Earth in particle accelerators where smashing particles together produces, completely unexpectedly, more matter than antimatter.  It might mean some of our fundamental understanding of astronomy and physics is wrong or that something else is happening which we can’t explain yet.  It’s a fascinating if frustrating observation!

JANUARY 2024

This month spectacular Ursa Major (the “saucepan” or “plough” shape) stands vertically above the horizon in the North. Follow an imaginary line joining the two stars at the end of the saucepan shape downwards and the next brightest star is Polaris, the pole star.  This variable star (it changes its brightness over a period of 4 days) is about 433 light years away, is visible all year round and it’s position in the sky is such that it always points towards magnetic north and is a useful marker if you’re lost at night !   Near the highest point above your head is another bright star called Capella, the fourth brightest star in our northern hemisphere after Sirius, Arcturus and Vega and part of a constellation called Auriga.  It’s only about 43 light years away and is one of the strongest sources of x rays in the night sky.  Although it appears to be a single star to the naked eye, Capella is actually a quadruple star system organized in two binary pairs.  Keep a look out for meteors during the first 12 days of January when the Moon is only a crescent, because the Quadrantid meteor shower that started late in December continues.  Look in the direction of Ursa Major about half way up the sky after midnight and you might see a meteor every few minutes. The peak happens around the 3rd January.  Regarding planets Venus is bright this month in the mornings and can be seen just above and to the left of the crescent Moon at about 7am on 8th January.   Saturn is shining in the evening sky.  An easy time to spot it will be around 5pm on 14th January when it will be just to the right of a beautiful thin crescent Moon and well worth a look if it’s clear.

Topic of The Month - Red Dwarfs

We tend to think we can see millions of stars in a dark clear night sky but in fact, unaided, even people with exceptional vision can only see at most 10,000 stars in a perfectly dark sky.  There are many, many more stars we can’t see without magnification. In fact of the sixty nearest stars to Earth fifty are too dim for the unaided eye. These are red dwarf stars, the most common type of star in the universe, which glow a dull red and far less brightly than bigger stars.  Red dwarf stars form just like other stars out of a molecular cloud of dust and gas.  Gravity pulls the swirling gas and dust together, and it begins to rotate. The material clumps in the centre, and when it reaches a critical temperature, fusion begins. However red dwarfs have very low mass compared to brighter stars. As a result, they have relatively low gravity crushing material down, a low nuclear fusion rate, and hence, a low temperature and so they emit relatively little light.  Even the largest red dwarfs have only about 10% of the Sun's luminosity. Their low rate of nuclear fusion means they use up their fuel much slower than brighter stars and some are thought to have existed since the beginning of time, 13.8 billion years ago, far longer than other brighter stars. Because of their longevity and constant heat output astronomers are interested in the many planets which can orbit red dwarfs because these planets will have had constant conditions for far longer than Earth. If these planets have the right conditions for life to have evolved, like liquid water, they might be more likely to support life simply because of the duration of the constant conditions.

DECEMBER 2023

In the winter the northern hemisphere of Earth is tilted away from the Sun (which is why it is colder) and towards the Moon (so the Moon is highest in the sky and brighter).  The famous Geminid meteor shower is definitely worth a look on the nights of 14th and 15th December in the south around midnight originating above the Constellation of Orion.  The Moon is about half lit on these nights so won’t disrupt viewing too much.    Often these meteors are bright and relatively slow moving across the sky and we can expect to see perhaps one every few minutes if we are lucky.  Have a look at Betelgeuse, the reddish star in the top left shoulder of Orion.   This star is a red giant 650 light years from Earth that dimmed suddenly last year making some Astronomers believe it was about to explode (go supernova).   If it did it would suddenly be visible day and night before fading away and it is certainly tipped as one of the most likely nearby stars to explode.  However, very recent data shows that changes have slowed and the dimming may be caused by a massive release of dust into the star’s atmosphere rather than its imminent explosion.  

Regarding planets Saturn will be visible just to the right of the Moon on 18th December and Jupiter can be spotted just to the right of the Moon around 5pm on 22nd of December.

Topic of The Month

Astronomers are adding knowledge to the question of how life started on Earth.   A popular theory is that meteorites hitting Earth had a role because they have been shown previously to contain water and a variety of chemicals needed for life.   However the problem until recently had been that the composition of meteorites which had previously landed on Earth might have been contaminated from the interaction of meteors with the Earth’s atmosphere or from the surface of Earth.  A report was published recently of a sample of a distant asteroid taken by Japan’s Hayabusa2 spacecraft which was delivered to Earth in a sealed capsule so we can be sure it wasn’t contaminated.  Analysis found that asteroid contained a surprising range of different chemicals and biologically important molecules including a variety of amino acids, amines and carboxylic acids which are found in proteins, vitamin B3 and Uracil, one of the four key nucleobases.   Nucleobases are nitrogen containing compounds that make up RNA, which is a molecule present in all living cells and is similar to DNA.   What is extraordinary is that so many complicated molecules had formed on the surface of the asteroid which is exposed to the terrifically cold and high radiation environment of space.  It seems quite possible given the vast numbers of pieces of asteroids and meteors hitting planets over billions of years that some will hit planets like Earth which have conditions to take these molecules and use them in the development of life.   It might also mean that life on other planets could be similar to life on Earth if they developed from a similar starting point.