The OAS word - March 2012 by Alastair Leith

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In this month’s issue PANNSTARS Beginners: Star Hopping Pole Reversal: what will happen Lord Rees of Ludlow Junior stargazers OASA News (Academy) Hugh’s View Your Observations

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Picture Credit: Andy Green taken near Reykjavik, Iceland

Contents Star Hopping ....................................................................................................................................... 3 Is the Earths Magnetosphere disappearing? ...................................................................................... 4 Lord Rees of Ludlow ............................................................................................................................ 6 Hugh’s View ........................................................................................................................................ 7 Junior Stargazers ................................................................................................................................. 7 Meteors ............................................................................................................................................... 7 Leonid Meteor shower facts! .............................................................................................................. 9 Online Astronomy Society & Academy News ..................................................................................... 9 Your Work ......................................................................................................................................... 11

Close Approach from asteroid Asteroid 2012 DA14 This 45m wide asteroid passes extremely close to the Earth on the 15th of the month. It reached magnitude 7 at its closest but faded rapidly after, but it will still be visible in binoculars or a small telescope. PANSTARRS

As Comet PANSTARRS approaches the Sun it hasn’t brightened as much as predicted. The best that can be expected of the comets brightness at perihelion is about 3rd magnitude (At the moment). BUT as said many a time before, comets are notoriously unpredictable. As it passes perihelion in less than two weeks’ time, anything could happen, so don’t give up hope on it yet! Even if it “only” reaches 3rd magnitude, it should still be a fabulous sight from around the 8th of March in the western evening sky just after sunset. Sourced from www.eagleseye.me.uk

Star Hopping Star Hopping The issue is, there are many objects in the night sky that are not visible to the unaided eye, even under the best conditions. The Technique Star hopping is the technique of using a series of bright stars hopping from one to the other in order to find the object you are looking for. The technique can be used to find a number of objects, including M51 (Whirlpool Spiral), and M1 (the Crab Nebula). We’ll describe it here though as a means of looking for an easier binocular object we’ll select M13 (the Globular Star cluster in Hercules)

The M13 Star cluster can be spotted by following 2/3 from the star ζ to η as indicated This can be done with the naked eye then look down the eyepiece, you should see the globular

Is the Earths Magnetosphere disappearing? It is true, it does seem to be getting weaker, which is of deep concern to scientists obviously from the point of view of the extreme solar storms we seem to receive. We have only to look at barren, sterile worlds like Mars to see the effect of losing its Magnetosphere had on Mars. It was believed Mars had a magnetosphere which, once the Martian iron core cooled, the field died. But what is this magnetosphere, and why is it so important to us? The magnetic field which surrounds the Earth is responsible for shielding us from Solar and Cosmic radiation. The main reason we see the Northern and Southern lights is due to the fact this field (shown below) is responsible for focussing the solar particles to the northern and southern poles which are not highly populated to cause major issues.

Experimental evidence and on-going investigation has shown that over the past 2-3 centuries, the Earths Magnetic field has weakened substantially. The initial concern that the field is dying seems to have been disproven, at least not in the sense the field died on Mars. No, although the Earths molten Iron core is indeed cooling, it is doing so at the rate of 100 degrees every billion years or so. As long at the molten Iron remains molten and dynamic it will continue to produce a field (in theory). The concern being that when the field died around Mars, it resulted in a considerable thinning of the atmosphere along with the loss of considerable water from the planet, leaving it the sterile world it is today. Of course with no field in place, the Martian atmosphere takes the full force of the solar and cosmic radiation. Otherwise the planet might have been as lush with life as the Earth is today.

Clearly the concerns for Earth would be the same fate as that of Mars, not only this of course but we rely heavily on the magnetic field for purposes of navigation and so forth, how much wildlife depends on the field is open to debate. 4 Copyright 2013 ÂŠ Online Astronomy Society all rights reserved

So if the Earth’s core is not cooling as Mars was, then why is the magnetic field weaking? Evidence found in soil samples suggest something more sinister and shocking is taking place, it’s not that the magnetic field is vanishing, it’s that the Earths Poles are flipping. That is the North and South poles are about to do the 180 degree flip, so in effect North will be where south is and vice versa. At present and this is a NASA simulation the magnetic field about the Earth looks as below left, however during the flip (reversal) it is expected it will resemble as on the right

How often does this happen? Charles Hapgood argued that each shift took approximately 5,000 years, followed by 20,000- to 30,000-year periods with no polar movements. The next one is due to be taking place now. In fact there is evidence it’s already started to happen. South Atlantic Anomaly This is an area where the magnetic field is closest to the Earth (200km from the surface). It is through this area NASA first noticed that satellites suffered disturbance as they passed through the area. It is in this area too that compasses will point in opposite directions

Further to this, that area is growing in size rather rapidly. So what will happen to the field once the reversal takes place?

We expect to possibly lose the field for up to 3000 years, which although it is a long time, it is not long enough to have a major detrimental effect on the Earth’s atmosphere (unlike Mars). However due to the fact there will be a much reduced shield from cosmic rays and so on we expect an increase in skin cancer. Of course other effects will include limited use of the magnetic compass. There are also concerns with the overall effect this will have on the weather and how exposed we will be to Super Storms.

Lord Rees of Ludlow Martin Rees 23/06/1942 Martin Rees was born in York 1942 and educated in Bedstone College, then from 13 at Shrewsbury School. Following his stint there he entered Trinity College Cambridge University where he gained a first degree in Mathematics. He then went on to read for a PhD under Dennis Sciama (same tutor as Stephen Hawking had) He has taught at Sussex University, and was Plumian Professor at Cambridge University until 1991 Made professor of Gresham College London 1975 then made Fellow of Royal Society in 1979 (picture credit of Wikipedia) In 1995 he was made Astronomer Royal, He became President of the Royal Society on 1 December 2005 until its 350th anniversary in 2010

Rees is the author of more than 500 research papers, and he has made important contributions to the origin of cosmic microwave background radiation, as well as to galaxy clustering and formation. His studies of the distribution of quasars led to final disproof of Steady State theory. He was one of the first to suggest that black holes power quasars and that superluminal astronomical observation can be explained as an optical illusion caused by an object moving partly in the direction of the observer. In recent years he has worked on gamma-ray bursts, especially in collaboration with Peter Mészáros, and on how the “cosmic dark ages” ended when the first stars formed. In a more speculative vein, he has (from the 1970s onwards) been interested in anthropic reasoning, and the possibility that our visible universe is part of a vaster “multiverse”. He is also a well-respected author of books on astronomy and science intended for the lay public and gives many public lectures and broadcasts. In 2010 he was chosen to deliver the Reith Lectures for the BBC, now published as "From Here to Infinity: Scientific Horizons". Rees believes the Search for Extra-terrestrial Intelligence is worthwhile, even though the chance of success is small.

Hugh’s View

Junior Stargazers

OAS Juniors aims to provide interesting articles targeted at our younger audience. Children are the future of astronomy and OAS hopes to not just educate but inspire the astronomers of the next generation. This month we look at Meteors…

Meteors

What is a meteor? A meteoroid is a small rock or particle of debris in our Solar System. They can range in size from a speck of dust to around 10 metres in diameter (larger objects are usually called asteroids as discussed last month). A meteoroid that burns up as it passes Earth’s atmosphere is known as a meteor. If you have ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor. A meteoroid that survives falling through Earth’s atmosphere and colliding with the Earth’s surface is known as a meteorite. The fastest meteoroids travel through the solar system at a speed of around 42 kilometres a second (26 miles per second) and Earth’s atmosphere experiences millions of meteors every day. A small percentage of meteoroids fly on a path that goes into the Earth’s atmosphere and then back out again, these are known as Earth grazing fireballs. Around 500 meteorites reach Earth’s surface every year but of those only around 5 ever make it to scientists for study. Meteorites that are observed as they fall through Earth’s atmosphere and later recovered are called ‘falls’, all others are called ‘finds’. To this date there have been around 1000 collected ‘falls’ and 40000 ‘finds’. What is a meteor shower? A meteor shower happens when a vast amount of meteors are observed in the sky at the same time. What makes up the annual meteor showers, like the Perseids or Leonids, is pretty special. What causes these two famous annual events is the Earth passing through the very long tail of two comets! The annual Perseids and Leonid meteor showers are made possible because of two comets that make regular visits to our solar system. The Leonids are caused when Earth passes through the tail of Comet Temple-Tuttle, which sweeps through our solar system once every 33.2 years. The Perseids are caused by Comet Swift-Tuttle, which visits us every 130 years. When these two comets visit our solar system, they leave behind trails that are thousands of miles long made up of very small particles of dust and ice. As Earth makes its annual journey around the Sun, it passes through the tails of these two comets. As our planet goes through these two trails of dust, the particles burn up in our atmosphere, which results in the meteor showers that we see in the sky.

Leonid Meteor shower facts! Each year around November 17th-18th the Leonid meteor shower peaks 1. Leonids are part of ancient history. Most of the shooting stars in the Leonids are the result of tiny bits of material blown off by a comet and wafting through space for centuries. 2. 3. Leonids don’t hit the ground. 4. 5. You can hear the Leonids. Meteors leave behind a trail of ionized gas and sometimes the signal from a radio station will bounce off this trail and catch loud whistling or buzzing noises before the fireballs become visible. for reading about meteors, check out The OAS Word next month to learn all about Saturn’s ring

Online Astronomy Society & Academy News

GCSE Astronomy GCSE Astronomy has been available to take as an exam for over a decade, and now you can enjoy the benefits of taking the course online! The Online Astronomy Society has teamed up with Dr Johanna Jarvis to make the resources and tuition available online, however there will still be a requirement to attend project write-ups and of course the final exam. Courses are £160 and include online tuition, worksheets and guides, plus the course material. This fee also includes both exam entry and final examination fees. Not bad eh! As a special offer, any one signing up to this course will also be eligible on a small discount on other OAS Academy courses (£10 instead of £12). A general breakdown of the package can be seen below

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AstroFest Was a complete blast, nice to meet many faces, it’s been a long time in chatting but not in meeting. Nice to meet Stuart Clark as well who kindly autographed copies of the directors books

Your Work It is pleasing to see a nice combination of work this month, some great sketches as well as images, we do try to encourage both types of activity to highlight astronomy is not just about pretty pictures. Something Alastair needs to remind himself of sometimes!

Well I've been struggling to assemble a large mosaic of today's sun but I messed up my flats so it will have to wait till tomorrow now. In the meantime here's AR11665 and a new group (?) appearing on the limb. Brian Ritchie

Paul Griggs: m27 vulpecular, very

pleased with this one, and my little Webcam: D

Ray Gilchrist is a rising star in the field of spectroscopy as well. Looking forward to seeing more of that as well in future ď &#x160;

NGC4216 and surrounding galaxies http://www.starhopper.at/ngc4216.htm http://www.photonhunter.at/NGC4216.html Yours sincerely, Dieter & Patrick

John Drummond on the last day of Star date 2013