This months cover image, Brian, Ritchie. The HA Sun
There has been a fair bit happening this month with Panstarrs being a bit of a disappointment mainly due to a combination of it not reaching its expected brightness and of course the weather. The Online Astronomy Society too has been expanding by offering more groups for the scientifically inclined, so we now for example have asteroid hunts (more on this below), plus the latest group which really is literally a stop press event which is the formation of our spectroscopy group. If anyone has ideas on other groups or activities we could start please let us know
OAS News Quite a lot going on lately, most summarized here. We are still accepting students for our distance learning GCSE Astronomy course which is due to start 1st June 2013. Dr Johanna Jarvis is the course tutor, who is herself a professional astronomer
Asteroids To complement our Asteroids group, we thought we would put this together
Hugh’s View By Hugh Allen.
Junior Stargazers Catherine Leith looks at Saturn’s Rings from a junior prospective
Your images A review of some of the highlights that have been posted on the Facebook page over the past month
This month has also seen the formation of the OAS Asteroid Hunters Group, run by Peter Gow. On our first hunt we discovered potentially 7 objects! (Of course these need to be confirmed). But good going guys! People interested in joining this group GCSE Astronomy is on course to start 01/06/2013 with our first students already enrolled. We currently have 7 students enrolled to take the GCSE Astronomy Exams, including our very own Catherine Leith. There are still places available; you have reserve a place by paying a non- refundable deposit with the balance payable before you start the course. So, what do you get for your £160 quid? Enrolment to the Online Astronomy Society Academy Expert tuition from out resident tutor, Dr Johanna Jarvis who is also a Professional Astronomer Access to worksheets and full learning schedule Access to forums, chat, and email support GCSE Text book provided Free access to resource CD material worth over £20 Make new friends! Opportunity to attend a passing ceremony at the end! If the above was not enough you will be given a year’s free access to other selected OAS Courses AND a free copy of the Eyes on the Skies DVD. The GCSE Astronomy course is studied remotely and only takes a 4 hour weekly commitment. Even the text book looks more like a booklet/ Magazine! The only commitment is you need to meet with your tutor to work on your projects and you MUST attend the final exam Not interested in taking exams? Not a problem, for £110 you can enrol like any regular student, participate in the projects, and final MOCK exam, at least get an idea of what the exam is like, maybe take it next time! Please note now that that Online Astronomy Society Academy is now able to accept over the phone payments from most Credit and Debit Cards.
Panstarrs Comet Panstarrs has had a mixed reaction with some people getting some fine images. However the weather has just not been favourable. However please see some lovely images taken by members. The Director tried very hard to view the comet, but to no avail
STOP PRESS!! It was a last minute thing but we have just rebranded the OAS Academy. Many thanks to all for their input on the design of the new logo
Thanks should also go to Kate Hiscock for her consultancy in redesigning the logo
Last but by no means least, We really don’t stop do we! We have just launched our new Cafe press shop selling apparel and other wonderful bits and bobs branded with our society logo and some of our space art
You can visit the shop here http://www.cafepress.com/oasacademy
Online Astronomy Society Asteroid Hunters Group Well done to the team, Pete Gow, David Warrington, and the Director Alastair Leith who did the first run of hunting this month, finding 7 objects between them, not bad for a first run, well done boys. Of course these need to be confirmed by the MPC With the founding of the Online Astronomy Society Asteroid group it seemed fitting to write a little about the motivation behind the group.
As we have seen lately, asteroids present a very real threat to Mother Earth. We have seen the recent shockwave that was created from an asteroid exploding over a Russian city named Chelyabinsk. Injuries of around 1500 people were the result of the shockwave created over Chelyabinsk which was around 9 miles above the Earth’s surface.. The event has been likened to 500 kilotons of TNT. That’s around 30 times the power of the Hiroshima atomic bomb! Before we discuss further events and group activities, it would be perhaps beneficial for us to discuss the terminology used in this article. We shall start with, what is an asteroid? The Wiki definition of the term “Asteroid”. Asteroids are small Solar System bodies or dwarf planets that are not comets. The term asteroids historically referred to objects inside the orbit of Jupiter. They have also been called planetoids, especially the larger ones. These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet. It would be useful to mention here asteroids are the oldest original (unchanged for the last part) remnants of the Solar System. So their chemistry can give us a valuable insight into how the Solar System formed. The different types of asteroids and so forth are not for discussion here. However it is enough for us to know these things orbit the Sun as the Earth does and come in all shapes and sizes. We like to think that many, if they collided with the Earth, would simply present us with a lovely meteor shower and that would be the end of it - a bit like been hit by solar particles that cause the northern lights. Where would we be without our atmosphere? To continue forward, it is now necessary to discuss some terms with you. During the course of this article we will meet terms like meteoroid, meteor, bolide, and meteorite and so on. We’ll now discuss each: Meteoroid This has been defined as a much smaller asteroid. Meteoroids, which have broken off from comets or asteroids, range in size anywhere from a small grain to a chunk of rock up to a metre wide.
Meteor When a meteoroid enters the Earth’s atmosphere, it is called a meteor. These are the streaks you often see in the sky, caused by the heat generated from this piece of space debris hurtling through our atmosphere. Meteors are often affectionately called shooting or falling “stars” but of course, this is only based on their appearance. Strangely enough MOST of these we see are actually particles from comet trails and are often no larger than a grain of sand would you believe! Bolide While the term bolide does not really have any official definition, astronomers often use it to describe a fireball - as seen in Russia recently - that reaches an apparent magnitude of -14 or brighter that tears through our planet’s atmosphere. A fireball’s brightness is similar to, or brighter than the full moon - so very difficult to miss! Often as in the recent case in Russia, and another event, Tunguska, these objects will enter the atmosphere and “explode” before it hits the surface, often causing a shockwave that is capable of smashing windows in buildings and causing all kinds of devastation in their wake. As we have seen, this sort has presented the greatest danger to us so far. Meteorite If a meteor survives the meteor/ bolide stage and impacts with the Earth’s surface, it becomes a meteorite. As discussed above this present great scientific interest as their chemistry would have been unchanged since the creation of the Solar System. Known Asteroids Most of the largest asteroids are already known. For example, it has long been my personal belief that Phobos and Deimos are both asteroids that have been captured by, and now orbit, Mars.
Deimos, image taken from the Mars Reconnaissance Obiter in 2008.
Phobos, image taken from the Mars Reconnaissance obiter in 2008.
However the first and largest known asteroid is Ceres which was discovered in 1801 by Italian astronomer Giuseppe Piazzi. Ceres is made of rock and ice. By contrast, Pallas is the second largest asteroid with a diameter of around 338. Pallas was discovered by astronomer Heinrich Wilhelm Matth채us Olbers on March 28, 1802. Like Ceres it was actually classified as a planet until several others were discovered forcing astronomers to change their classification. Ceres, also known as 1 Ceres, is not only the largest asteroid that we currently know of with a diameter of almost 600 miles, but it is the only dwarf planet in the inner Solar System. While it is believed to be the largest asteroid discovered to date, it is not the largest dwarf planet. That title belongs to Eris, which at an estimated diameter of some 1445 miles is more massive than fellow dwarf planet, Pluto.
Interestingly enough Ceres represents around a 1/3 the mass of the asteroid belt. It is also large enough to maintain a near spherical surface (unlike other asteroids).
Comparison of Earth, Moon, and Ceres
Another well-known asteroid is Vesta, which for reasons of attempting to keep this article to a reasonable length, will not be discussed here since the objective is to give you a flavour of what asteroids are and look like. The below figure should help represent more of the better known asteroids
Pallas
and their comparative sizes.
These are the larger known asteroids. Their orbits are well plotted and they present no immediate threat to Earth. However, in the depths of space, there are thousands of smaller lumps of rock that we don’t know about that could be a threat to us in the future. When we say a threat though, what do we mean? Many of us would assume the atmosphere would shield us for the large part. Well let’s take a look at where it wasn’t sufficient. We could not write this article without discussing the recent bolide that exploded above Russia. As the object entered (un- monitored) the object ploughed through the atmosphere as we saw on the news and exploded about 14 miles above the heads of the people of Chelyabinsk, generating a shock wave that caused the damage we mentioned above. This was the worst event to have happened since Tunguska; another bolide [recently it has actually been suggested that Tunguska was a comet due to sightings of noctilucent clouds] that entered the Earth and exploded over the Siberian Forest, flattering thousands of square miles of trees. It seems no actual crater was left; however, the explosion (around 6km from the surface) caused huge devastation. Fortunately the area is not densely populated so no reported casualties, in contrast to the more recent disaster we saw in the Chelyabinsk region where many of the meteorites fell. The Chelyabinsk event happened at the time of 2012 DA14 approaching the Earth, however, experts have reassured us that the two are not related. Though these were severe enough, with the second impact being the only one so far to have caused several casualties, there was one impact that is accredited with wiping out the dinosaurs 65-66 million years ago. We know it had to have been a sudden event as the dinosaurs suddenly died out, it was not a gradual or evolutionary process. The Cretaceous–Palaeogene extinction event as it’s called, was an intense, global mass extinction of an estimated 75% of animals and plants, most notably non-avian dinosaurs.
An artist’s impression of how the asteroid must have entered the atmosphere.
The impact crater is believed to be under Chicxulub on the coast Yucatan, near Mexico. The average diameter of the crater is 112 miles.
So in reverse chronological order we see asteroids are continuing to be a threat to civilisation as we know it. The good news is most of the larger objects are known, however it only takes an impact from an asteroid of less than a mile in size to repeat the kind of devastation that wiped out the dinosaurs. Online Astronomy Society Asteroid Group This group was set up with the assistance of Ryan Laird and Alastair Leith (author of this article!) and is run by Pete Gow. The aim of the group is to analyse data from Comet Panstarrs in search of asteroids, a project which also has the participation of UKSEDS and other groups across the world. So what plans are there in place to protect Mother Earth from such an impact? The answer is, at the moment, not a lot. Early detection is clearly crucial; the question is how to deal with such a catastrophe if it were to happen. Many ideas are being suggested from the use of nuclear devices to destroy any possible body heading our way. However the issue with that is the danger from smaller fragments that might still enter the Earth and cause damage. Not to mention the danger of nuclear fallout. Detection As discussed this detection is taking place, the difficulty is space debris, which is heading towards Earth, all the time. These objects are often very faint either due to their size or distance. For example, there was one such object that was known about 24 hours before it collided with Earth with Fragments landing over Africa Author – Alastair Leith. Alastair is Director of Online Astronomy Society and the OAS Academy. He also help set up the OAS Asteroid Hunters group
Lambda Tauri is visible to the naked eye with a magnitude of 3.41. It is actually a binary star separated by less than the distance between the Sun and Mercury. The two stars complete an orbit around their common centre of gravity in only 3.95 days. What’s more, the orbital plane of the two stars lies close to our line of sight which makes Lambda Tauri a wonderful example of an eclipsing binary. When the fainter A-class star passes in front of the brighter B-class the magnitude dips briefly to around 4.1 (the primary minimum). There is also a much smaller secondary dip in brightness when the eclipse occurs in the opposite sense. All of this is wonderfully visualised by plotting Lambda Tauri’s light curve – a graph of its brightness against time. I pasted in the corner of my image an excellent example from a paper by Joel Stibbins in the May 1920 edition of the Astrophysical Journal. On the night I captured my image I think the star was just over a day beyond its primary minimum, so pretty much at maximum brightness. (Image details: 8” Meade LX90 at f/3.3, Meade DSI II colour camera, stack of 18 x 4sec exposures, February 17th 2013 at 19:00 UTC) — at Near Wells, Somerset UK
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 Saturn’s rings…
Saturn’S ringS
Saturn is a funny looking planet isn’t it! As we have discovered in past OAS Juniors articles it is not the only planet to have rings but Saturn’s rings are the biggest and brightest. An astronomer called Galileo was the first person to see Saturn’s rings. He spotted them while looking into space through a telescope in 1610. That’s almost 400 years ago! Scientists have been trying to learn more about Saturn’s rings ever since. One thing we know for sure is that the rings are made up of ice and rock. These pieces vary in size; some are as small as a grain of sand, others as big as a house! But scientists are not sure when or how Saturn’s rings formed. One theory is that the rings may have something to do with Saturn’s many moons. Earth has only one moon but Saturn has at least 60 moons orbiting it that we know about. Asteroids and meteors sometimes crash into these moons and break them into pieces. The rings could be made up of these broken pieces or they could also have been created from material left over from when Saturn first formed. From far away Saturn looks like it has seven large rings. Each ring is named for a letter of the alphabet. The rings were named in the order that they were discovered. The first ring discovered was named the A ring but it is not the ring closest to or farthest from Saturn. Some of the rings are close together while others have large gaps between them. The rings do not sit still; they circle around Saturn at very high speeds. A closer look would show you that each large ring is made up of many smaller rings. These small rings are called ringlets and it is believed that more rings and ringlets could still be discovered. Saturn is much larger than Earth, more than 700 Earth’s could fit inside it. The rings are thousands of miles wide, if there were cars in space, it would take more than a week to drive across some of Saturn’s rings! On the other hand the rings are quite thin. They are only about 30 to 300 feet thick. The NASA spacecraft Cassini has been orbiting the planet since 1997 and has taken amazing pictures of Saturn’s rings.
Saturn’S ringS queStionS! Now that you have learnt all about Saturn and her rings can you answer the following questions? 1. 2. 3. 4. 5.
What other planets have rings? (There are 3 of them!) What are the rings made up of? Who was the first person to see the rings? How many main rings has Saturn got? What spacecraft is orbiting the planet now and sends back pictures of the rings?
Many thanks for reading OAS Juniors, next month we will be looking at the amazing Northern Lights and how they are created!
Gary Palmer: Another shot of Jupiter taken on the 2 March 2013 with a Celestron edge 9.25 and a DMK camera. I’ve been playing with the processing on a few of these.
Bastian Leppin, Messier 51 & Galaxie IC 4263
From a distance of almost 30 million of light year, lurking among the stars of Leo, the elegance of the barred spiral of NGC 2903 is astonishing. The central core of this realm of stars shows some hot spots, believed to be young globular cluster. It was discovered by W. Herschel on 16 Nov. 1784. The high-res image above was taken with the Plane Wave 17 robotic unit part of the Virtual Telescope Project. 15, 300seconds images were averaged: images were unguided, trusting the robotic Paramount ME mount hosting the optical tube. The image scale is 0.9″/pixel
Toni Scarmato Final Image of Comet C/2011 L4 (Panstarrs) taken this evening with an APO Tele 300 mm and Canon 10D at ISO 400. Compared to other nights the camera was located on an equatorial mount with RA and tracker so I could put 120 seconds each and to add 5! I applied to the original image processing filters that seem to bring out the inner part of the coma and tail! I'm not sure; however, about the quality of the result because the filters can create artefacts, but after seeing some images with high resolution and wide field think that the structures could be real! Magnitude estimated 2.6 in 7x50 binoculars!
David Eagle Tonight I finally got a look at Comet PANSTARRS between the clouds. It's not spectacular, but it’s there with a nice fan-shaped tail.
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