Absolute Beginners

The Night Sky September 2019

As the night sky creeps into early evening I have decided to dedicate this month’s article to all of the budding young (or old) astronomers of Embsay and Eastby. Astronomy can be very rewarding and a long standing friendship and fascination with the night sky can be with you forever. The more of us there are, the more chance we have of keeping our dark sky!

Absolute Beginners.

When we look out into the clear night sky we see so many stars. Everyone needs help in working out how to remember what and where things are. A very good start is to remember that the night sky acts like a big piece of paper pinned down with a drawing pin slowly moving around this point.

Some stars near the drawing pin will be seen all year round and others on the edge of our paper will go out of sight for parts of the year, reappearing at other times.

We also remember where many of the stars are by grouping them into patterns. If we can remember some of these shapes, we will be able to find our way around. Some of the shapes that are near the ‘drawing pin’ are always visible, including Cassiopeia, Perseus, Ursa Major and Ursa Minor. This last pattern, Ursa Minor, is special because at the end of the shape is the place where we pushed the drawing pin in and the whole sky spins around this point.

The next important thing to remember is that stars are suns. Many are like our own but some are much smaller and others are huge.

Except for our own star- the sun - they are very, very far away.

Most (but not all) of what we see with our eyes on a dark night belong to a group of stars shaped like a big dish. Often we can see a band of light made up of millions of stars across our sky, like a carpet of sparkling jewels. This is our galaxy and our home, the Milky Way.

There are other things in the night sky apart from stars. There are objects that go around our planet. The biggest and brightest is our moon but we don’t have to stand still for long on a dark night to spot other fainter things move across the sky. The best one to try to spot is the international space station. We can use a mobile app (ISS Detector) to help us find the next time it passes overhead. We will know when we see it, as it can be the brightest thing in the night sky other than the moon. Fainter objects go around our Earth such as nearly 2000 artificial satellites and space junk that we can see catch the sun’s rays whilst in orbit.

We on the Earth go around our sun, just like other planets and their own moons. The planets look like stars. However, a general way of telling the difference is that stars twinkle and planets don’t. As the planets go around the sun some may not be visible because they are too close to the sun or they may even be on the other side of the sun. When they are in our night sky they can be amazing, particularly with binoculars or a telescope. Jupiter and Saturn are low in the south at the moment but once seen you will instantly be hooked, guaranteed! Many pieces of rock/ice circle the sun and sometimes cross the Earth’s path. Some pieces are very large and others are small. When we pass through this spot each year we are rewarded with a shower of bright streaks at night that can be spectacular.

There are other deep sky objects, including fuzzy shapes which are truly astounding if you decide to take the interest further. However, these have to be observed with the aid of a telescope. For now, if you are starting out, binoculars are a great way to study the night sky, no complicated setting up, just grab them and go!

Follow my articles each month and slowly you will get to know more about astronomy and cherish our very beautiful dark night sky.

If you have enjoyed reading this article, don’t forget you can refer to previous ones on my blog at:

http://milandavidovic55.wixsite.com/mysite

Clear Skies.

Milan Davidovic

The Summer Triangle

The Night Sky August 2019

This time last year I wrote about the Summer Triangle, three bright stars that out-shine our light nights during this month. You can use this triangle to help you find your way around the night sky. The triangle is a large pattern but easy to spot as the three stars are almost the first stars to shine through. If you look south, half-way up the sky (over the top of the quarry from Embsay) you will see the lowest of the three stars, Altair. Now look almost overhead to see Deneb to the left, and Vega to the right, to form our triangle.

Using the triangle.

· Trace a line from Vega to Deneb across the sky and it points to the Andromeda Galaxy. This is the nearest major galaxy to us and on a dark night you can see it with your naked eye.

· Starting at Deneb through Altair towards the horizon, you will find Jupiter and Saturn low in the sky. Both planets and gas giants are visible unaided.

· Starting at Altair and working upwards, you will see a very small triangle with a few stars in-line just ahead of the triangle. Directly above these is the Dumbbell Nebula.

The Dumbbell (M27)

The life-cycle of a star has two routes, depending on how large the star has become. Although when we look at the night sky most pinpoints of light look a similar size, stars can vary incredibly in size.

An average-sized star, like our own sun, will in time burn out its fuel and enlarge to become a Red Giant. It will then form a ‘planetary nebula’. This is its outer envelope being blown away as the core collapses to form a White Dwarf. In effect this is a dead star, where fusion has stopped. When we observe the Dumbbell we are seeing the nebula remnants (nothing to do with planets by the way!)

To see the nebula, you will need to allow your eyes to adapt to the low levels of light, then you will be rewarded with a very unusual sight. Not pinpoints of light, but a glow made from gas that has been expanding from a central star that collapsed to form a White Dwarf. The dwarf star is hardly visible at this distance. However, it was similar to our own sun but now is at the end of its life. The overall view looks like a faint diabolo, bow tie or even an apple core. Another Messier object to tick off your list (see my article May 2019)

The second route of a star’s life-cycle is followed when the size of a star exceeds 25 times the size of our sun. As it uses all of its fuel it transforms into a Red Supergiant then eventually explodes into a Supernova leaving behind a Neutron Star or Black Hole. The ‘left-overs’ from the explosion are called supernova remnants, one of the more famous being the Crab Nebula.

Perseid Meteor Shower (12th/13th August)

The annual Perseid meteor shower, one of the best of the year, coincides with a rather bright moon this year. Therefore, most meteors will be washed out by its brightness, but not all! This shower can have a rate of up to 100 per hour as the Earth passes through the debris of the great comet of 1862 known as Comet 109P/Swift-Tuttle. Looking roughly North East and half way up in the sky you find the ‘radiant’, where they will appear to originate.

If you have enjoyed reading this article, don’t forget you can refer to previous ones on my blog at:

http://milandavidovic55.wixsite.com/mysite

Clear Skies.

Milan Davidovic

Heading for the stars!

The Night Sky July 2019

In 1969, and as a young boy of 13, there was no greater dream for me than the mystery of space and being an astronaut. Brought up on Fireball XL5 and Thunderbirds, my world seemed to be heading for the stars! I had been given my first telescope and was desperately looking out during the mission for the shiny glint of Apollo 11 as it raced towards the Moon and Tranquillity Base. The space age had arrived and I was witnessing perhaps the most remarkable human achievement in the history of humankind.

Looking back now, I am still in awe, perhaps even more so, as the finer details emerged of that trip and of the level of technology that supported the Eagle lunar module as it descended to the surface on 20th July 1969. The Apollo’s guidance computer had 2K memory; my personal computer (ZX80) in 1980 had double that! My current mobile phone has more power than ALL of the NASA computers back then, that put two astronauts on the moon. A few years ago I was privileged to stand on 39A launch pad where it set off, akin to standing at Plymouth Sound where the Beagle set off with Darwin on board. Both journeys were remarkable and a testament to human ingenuity and bravery. Experiments were left on the surface of the Moon that are still in operation. The Lunar Ranging experiment bounces back a laser beam via reflectors left by the Lunar Missions. It has shown that the moon is spiralling away from us at a rate of about 4cm a year and can be measured with millimetre precision. This month sees a partial lunar eclipse exactly 50 years ago to the day that Apollo 11 set off for the moon. Just over half of the moon will be in shadow at about 10.30pm on 16th July. A timely and fitting reminder.

Draco

The constellation of Draco is one of the least known but one of the largest in the northern hemisphere.

Draco means the dragon or huge serpent in Latin. Amongst many legends and stories, it is famed for being the serpent that tempted Eve in the Garden of Eden. Despite its size, the stars that make it up are not very bright but the constellation never sets, so if it’s clear it will always be visible if you know where to look. Thuban, a star in this constellation, was the Pole Star at the time of the building of the pyramids and they were built with shafts that directly pointed and aligned to the star, letting the light shine into the structure. Currently we know that Draco has nine stars that have planets called exoplanets. Kepler-10 is famous for being the first star to have at least 2 planets in orbit around it. After 10 years of searching a small patch of space, the Kepler spacecraft discovered a total of 2,600 planets in total - some perhaps capable of supporting life. It did this by watching how some stars regularly dim as planets pass in front of their host star. Another interesting object within the constellation is The Cat’s Eye Nebula (NGC 6543) which is now believed to have been created just a thousand years ago when a star started to blow off layers of material, but even so, that star is still 10,000 times brighter than our own! Despite this, you will need a medium sized telescope to see it.

The two stand-out planets to spot this month are Jupiter and Saturn. Jupiter is by far the brightest and on 13th July will be just below the moon. On the same night, Saturn is to the left but much fainter. It is possible to see its rings and one of its many moons, Titan, the largest. Both Saturn and Jupiter are quite low in the sky looking south.

If you have enjoyed reading this article, don’t forget you can refer to previous ones on my blog at:

http://milandavidovic55.wixsite.com/mysite