The National Park Dark Sky Festival for the Yorkshire Moors and Dales…

In the UK we’re getting more and more detached from what the nights sky looks like, we have a knowledge of some of the constellations and asterisms. Some know the plough and its use to find the pole star, many can find Orion during winter with his distinctive belt, but what the sky looked like to our ancestors and how it changed during the year indicating the coming of seasons is something we have lost, how the appearance of the Summer Triangle, made of the stars Vega, Altaire and Deneb and its significance relating to the return of the summer months.

The encroachment of light pollution has such a significant effect on how we live our lives, it makes us feel safe in dark cities, but nature of the design and shear number of unnecessary lights is drowning out the night. The Bortle scale is a measure of light pollution and what we should be able to see. The scale runs from Bortle 9 to 1. 1 being a perfect dark sky sight, the spiral arm of our galaxy, the Milky Way, should be able to cast a shadow on a moonless night all the way to Bortle 9, which would be equivalent to looking up at the sky in the middle of a major city.

The glow of Halifax as Orion rises

You can judge the levels of light pollution in your local area by finding Orion the Hunter. Look south east from around 19:00, the later the better! Orion appears as a rectangle with three stars making up its belt. The top right star is Betelgeuse (the subject of our previous Blog!) the top right is called Bellatrix; the bottom line of the rectangle is Rigel and Saiph. Count the stars within the rectangle, you can include the belt and the rectangle forming stars. To see no more than 10 indicates you are in a heavily light polluted area. In a dark sky site, you expect to see thirty, a remarkable sight!

There are some amazing dark sky sites around the UK, the Brecon Beacons, the Lake District, Dartmoor, Kielder Forrest, Snowdonia and The Yorkshire Dales to name a few, they’re locations where we can get a feeling of what our night sky would have looked like in the past. To see a fuzzy band of stars which make up our own galaxy and then to look between Peruses and Cassiopeia to see a faint smudge, our nearest neighbour Andromeda.

The National Park Dark Sky Festival is an event that aims to claim back the night, to bring awareness of the level of light pollution. The festival begins on the first of February and runs through to the end of march is an amazing opportunity to reconnect with our ancestors and see the wonders of the universe, simple to observe the number of stars makes finding the constellations a challenge! For this Dark Sky Festival, we have teamed up with Go Stargazing and The Tan Hill Inn, the highest and best (probably) pub in the UK. A location where the aroura is visible! Go Stargazing and their astronomers aim is to make astronomy accessible for all. We’ll be at Tan Hill on for the week beginning the 17thof February and on Friday the 21stand 28thof Feb.

To combat light pollution, you can find different filters for your telescope or camera. It should be warned that these won’t make objects brighter, only increase the contrast between them and the sky! How filter work is…. our streetlights work via florescence, that is the gas is excited which emits photons of light of a very particular frequency. The Filters work by absorbing photons of a similar frequency thus removing the photons of light emitted from the fluorescence of that particular element! All good you may say, but! The light from distance stars, galaxies or nebulae will have to pass through the filter regardless, meaning light will be absorbed, the result? Objects will appear dimmer although the contrast will be higher. The best method to see distant objects either with binoculars or a telescope or the naked eye is to get away from all streetlights and other sources of artificial light. There are some fantastic locations to do this, dark sky discovery sites or Dark Sky Parks. Visiting these locations, you’ll not only be amazed at the number of stars that will appear as your eyes acclimatise to the low levels of light, but it will also give you the opportunity to form a bond with our past, our ancestors as little as 50 years ago but also as far back as we have been able to look up! Comets, galaxies, the Milky Way have all been immortalised in some form, Hailey’s Comet appearing in the Bayer Tapestry, something many of use many not see in the future (2062/2063) due to its reflected light being drowned out from photons emitted from artificial sources.

To find out more about dark sky sites in the UK or what events are taking place in the National Dark Sky Festival visit a comprehensive list of nearby events.

Or you can join astronomers from Yorkshire Astronomy and Go Stargazing at Tann Hill Pub, the highest and (probably) the best pub in the UK, situated in the Yorkshire Moors, a dark sky discovery site in February. Look out for our article in Sky at Night in February!

Clear Skies!

A Supernova in Orion!

The constellation of Orion, the Great Hunter, a collection of stars that is instantly recognisable. Orion’s belt comprising of three stars with his sword hanging by his side is an asterism that many of us are familiar with, particularly at this time of the year when Orion is high in the night’s sky from about six o’clock. But what is with the stories reporting that Betelgeuse, a bright orange star found in the left shoulder of Orion, is about to explode in a supernova?

Firstly, Betelgeuse is a super red giant located about 640 light years away from earth, 640 light years means it will take light 640 years to reach earth and so when we look at the star we are seeing it 640 years in the past. Similarly, when we look at our own star, the sun, we see it 8 minutes in the past. Betelgeuse is a massive star; if it was in the place of our sun it would take up the space up to the orbit of Jupiter. Betelgeuse is classified as alpha Orion or a Orion, this means it is the brightest star in the constellation Orion. It is also a ‘runaway star’ A star that is travelling faster than the interstellar medium it is sitting in, for Betelgeuse to be travelling faster than the matter that’s surrounding it something must have either pulled it or pushed it away from its position. This could be gravity; something with mass pulling it, like a galaxy or other body. Or it could be an explosion that is pushing it away - a supernova, one of its neighbouring stars exploding.

Super massive stars burn through their fuel (hydrogen and helium and their isotopes; helium and hydrogen but with different numbers of neutrons) incredibly quickly. In the prime of its life, Betelgeuse would have been fusing hydrogen and making heavier elements whilst emitting immense amounts of energy. Because of its huge mass the gravitational force trying to squash it down would have been battling the thermonuclear force trying to blast the star apart. As the fuel in its core is exhausted the force of attraction, due to gravity, begins to win this battle compacting the star. This causes the temperature to skyrocket and the hydrogen and helium in the outer core and any heavier elements in the core fuse to release incredible amounts of energy. This tips the battle of gravity and thermonuclear force in the other direction, causing the star to swell. The side effect of this is that the star cools and takes on a red colour. When we see Betelgeuse now, it has a orange, red appearance to it, a Super Red Giant. The colour change of a star relates to its temperature and gives us an idea of what is happening in the core of a star and where it is in its life cycle. Our own sun is in its Main Sequence.

Eventually the force generated from the nuclear reactions in the star’s core will not be able to hold up gravity. At that moment the core will instantaneously collapse. The shockwave will obliterate the outer layers of the star; this is a supernova - and what will be left?

The Crab Nebula - A remnant of a Supernova.

The core, a body of immense density. Our sun will meet a similarly sticky end; only the shock wave will not be anywhere near as impressive! The core of Betelgeuse will have two pathways. The matter will be squished together creating a body made of neutrons. These neutrons, according to uncertainty and something called ‘neutron degeneracy’ should not be able to get any closer together, but if the core has a mass of 3.4 times that of the sun at this point then the neutrons won’t be able to hold up gravity. The result? The phantom of astrophysics…the singularity or BLACK HOLE!!

Betelgeuse is a variable star with a regular pattern in its dimming. The cycle has a period of just under 6 years. There is also a faster cycle with slight changes in its brightness of around 550 days. The current dimming of Betelgeuse is greater than previously observed but it could be that these two cycles of dimming have overlapped and as a result we are seeing a more obvious change in brightness than what we usually see. It is also very unusual for a star to undergo a dimming stage prior to a supernova. Betelgeuse will supernova and when it does it will outshine a full moon and be visible during the day. In astronomical times this will happen very soon, but unfortunately for us, very soon is 100,000 years away!

Find Orion and Betelgeuse by facing east after the sun has set and its dark. The Belt is the easiest thing to find. Three stars in a line, around the belt there appears to be four stars making up a rectangular box. Betelgeuse is the top left. Check out events and workshops page to find more wonders of the night’s sky and join us for an astronomy workshops night walk!

#clearskies! #astronomyatdovestone #finalydark #bringbackthenight #astronomyinthevalley

From November look East from about 24:00, the unmistakable shape of Orion the great Hunter will appear above the horizon, as the winter gets closer the Constellation will arrive earlier and earlier. The bright star in the top right hand corner, Betelgeuse, a red supper giant. If you draw a line from Orion's Belt down to the horizon you’ll come across the brightest star in the Northern Hemisphere, Sirius. One of the best images of Orion is the Great Nebula of Orion. Find the Belt of Orion and you;; see his sword, about half way down the sword you’ll find the Greta Nebula, using the naked eye it is just about visible, but with binoculars you will make out a grey fuzzy object that you would mistake for a cloud, using a telescope of four inches or more you will be able to make out some structure of the nebula.

Drawing a line from the belt in the other direction you’ll come across a smudge, this is M45, the Pleiades, a Star Cluster that orbits around our Milky Way. At a distance of around 444 light years away it is only the seven brightest stars that can be seen hence its name the Seven Sisters. The brightest is Alcyone.

From dark sky sites the Milky Way will be visible. We sit in the spiral arm of the Galaxy, when we look out we can see the arm, the higher density of stars give it an appearance of a smudge, or faint cloud across the sky. Look for Cassiopeia, a distinctive constellation in the shape of a ‘W’. The Milky Way runs like a line through Cassiopeia.

As the dark skies get darker and earlier from the darkest of sites you can make out Andromeda, our neighbouring Galaxy. The Milky Way is not alone in space; we have a number of galaxies near to us, called The Local Group. Andromeda is one of these. It is about 1.3 times larger than the Milky Way. Look due west and find Cassiopeia. From the middle point of Cassiopeia go down to the bottom tip of the ‘W’ heading towards the horizon, Andromeda sits on this line. A pair on binoculars will enable you to see it as a disk shaped smudge but a telescope of 4 inches or bigger will resolve the galaxy.

The star of the Winters Astronomy is in fact the planet Venus, known as the evening star. Because its so close to the sun its difficulty to see and isn’t visible at all during the night. From the end of November, look South West just after the sun has set. Venus is visible as a bright star just above the horizon.

The best Meteor shower of the season, the Geminids, begins on the 7th of December and ends on the 16th, but the peak is on the 14th of December. Meteor showers are given there name depending on where in the sky the appear to originate from. In this case the constellation Gemini. The source of the meteors is the asteroid 3200 Phaethon, making the Geminids only one of two showers not from a comet! Because of this they have trace amounts of metals causing the shooting stars to have a variety of colours!