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Lancashire Astroguy

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About Lancashire Astroguy

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  1. Its not exactly Santa bringing it to me, but after suddenly realising how daft I have been forking out £20-30 a month on an ancient mobile phone with a pay-as-you-go scheme, I have decided to take the plunge and order my first smartphone on a monthly contract (a Samsung Galaxy S4). Should be delivered later today! I'm hoping there will be lots of fun Astronomy apps I can download - not least of which is the one where you can point the phone at the sky and it shows you a star map of where you are looking. If anyone else has an Android phone, I'd love to hear their recommendation for Astronomy apps!
  2. Good on Google for celebrating today on their title page the birthday of one of the giants of 17th century astronomy and physics - Johannes Kepler. There is even an animation demonstrating accurately not just the first but also the second law of planetary motion! Whilst most of the general public are familiar with Galileo and Newton, the name of Kepler will be less well known to them. Yet he was a mathematical genius whose work on the motion of planets finally buried the geocentric theory forever, and led directly to Newton's formulation of the Universal Law of Gravitation. Indeed, in his discovery of the third law of orbital motion (period squared proportional to radius cubed), Kepler must have only been a hairs breadth away from deriving the Law of Gravitation himself. Certainly everyone today who uses satellite technology in their everyday lives (which lets face it is pretty much everyone!) owes a debt of gratitude to Kepler, as well as Newton, for making this possible.
  3. I'm a secondary Physics teacher, and I have to say that there is always a large reservoir of excitement and enthusiam for all things space amongst the younger end of the age range i teach. In fact, i am fortunate enough to teach at a grammar school where we put a large emphasis on academic learning, and we do a pretty good job of maintaining that interest (we have over 130 students studying A level Physics in the sixth form, and most will study the Astrophysics option at A2 level). It is the case however, that there is a significant "anti-learning culture" in many schools, and to be honest a student can easily attain an A* in GCSE "Dual Science" without having any real understanding of astronomy (or indeed science in general) at all. It fills me with dread when I see that "celebrities" like Joey Essex, a 23 year old reality TV star, go on a TV program watched by millions and proudly declare that he can't even tell the time on an analogue clock, as if that is some sort of badge of honour. Unfortunately, the likes of Essex are admired and respected by a lot of young people who wouldn't dream of watching a program presented by Brian Cox.
  4. The real fun would be to set up two well-seperated telesopes on the Moon and link them together as an interferometer. There would be a possibility then of imaging exoplanets, not unlike the long-planned but continously postponed NASA terrestrial planet finder.
  5. You never know - you should hold onto it. Tesco might be interested in a few decades time.
  6. I disagree. These companies are taking advantage of people at their most vulnerable by misleading them into buying something which is essentially worthless and meaningless. Most of the customers of these companies will be recently bereaved people with little or no astronomical knowledge, who may well genuinely believe that they are buying the right to officially "name" a star after their loved one. Whilst these people may well be happy at the time of purchase, I'm sure they will be far from happy if they find out later that they have been conned. I'd be interested to know how much these companies charge - I bet it won't be cheap and, lets face it, their profit margin will be nearly 100% as their overheads are practically zero (just a website and a paypal account)! I don't mean to offend our American members, but it seems most of these companies are in the "land of the free". As usual, in the US it seems that the right to make a fast buck at the expense of others overcomes any moral or humanitarian considerations.
  7. The apparent visual magnitude of an object is based on the radiant intensity of the object as viewed through a "V" band photometric filter. Given that the "V" band filter is a reasonably close (though not perfect) match to the spectral response of the human eye, comparing visual app mags of different objects should (in theory at least) give an indication of their relative brightness as viewed by the eye, regardless of their colour. A good example of this is Betelgeuse and Rigel in Orion. Both stars have roughly the same intrinsic luminousity across all wavelengths (about 120,000 x Solar Luminosity). However, Betelgeuse is significantly closer than Rigel to us, so one might expect Betelgeuse to appear brighter than Rigel. In fact it clearly appears dimmer and this is reflected in its apparent visual magnitude (0.42 compared to 0.12 for Rigel). The reason of course is that Betelgeuse being a much cooler star emits more of its energy towards the red end of the visual spectrum, but this peak is heavily attenuated by a "V" band filter (and the human eye).
  8. I'd like to say the star marked "Marc & Lara" was actually Arcturus (brightest star in the northern hemisphere!!!), but its actually in the wrong place. In fact, it seems the asterism of the Plough has been roughly pasted over a photograph of part of the Milky Way (which doesn't even pass through the Plough!). Shabby, tacky and horrible. These sites should be banned.
  9. You would be hard pressed to casually notice a difference between magnitude -2.5 and -2.9. By comparison, the difference between Castor and Pollux (the two main stars of Gemini) is also 0.4 mag and they look pretty much the same brightness to me (albeit Pollux being slightly orange). I guess its down to the human eye being a logarithmic rather than a linear detector of light. Nonetheless, I understand seasoned observers of variable stars can sometimes estimate magnitudes to within +/-0.2 or even +/-0.1 if there is a suitable comparison star in the field of view. Interestingly though, using the numbers above (mag -2.5 and -2.1 for the two planets), then just before and after the transit they would appear to be a single object that was even brighter (mag -3.1), given that none of Jupiter's disk would be hidden. A difference of 0.6 mag (0.57 mag to be precise) should be more noticeable. Much more than an arcminute apart, however, and your eye would start to seperate them.
  10. If the disk of Mars was completely inside the disk of Jupiter, then the combined object would be brighter (i.e. have a more negative apparent magnitude) than either planet individually. This is because the disk of Mars will be brighter than the portion of the disk of Jupiter it is replacing. Mars is (on average) 3.4 times closer to the Sun than Jupiter, and therefore receives much more illumination from the Sun. If its surface was as reflective as Jupiter's cloud, then its surface brightness would be 11.6 times that of Jupiter (3.4 squared - light intensity drops as an inverse-square law). In fact, Mars is less reflective than Jupiter (albedo of 0.15 rather than 0.52). This means the Martian disk has a surface brightness 3.3 times that of the Jovian disk (3.3 = 11.6 * 0.15 / 0.52) In other words, the disk of Mars is 3.3 brighter than that part of Jupiter it would be blocking during a transit. This allows us to do a few simple calculations. Lets say the transit occurred near opposition of both planets when Jupiter had a app mag of -2.5 and Mars had an app mag of -2.1. The hidden part of Jupiter's disk would have a magnitude 1.3 fainter than Mar's disk, e.g. -0.8 (1.3 = 2.5 * log 3.3). This corresponds to 20.9% of Jupiter's total brightness (0.209 = 10^^(0.4 * -1.7)). Thus Jupiter's brightness has been reduced to 79.1% of its original value. However, if we multiply 20.9% by 3.3 we get 69% ... adding this onto 79.1% we calculate that the combined object will have a brightness 148% (or 1.48 times) that of Jupiter on its own before the transit. Converting this back into magnitudes we finally get our answer ... magnitude -2.9 for the combined object (2.5 * log 1.48 = 0.42, so approx 0.4 magnitudes brighter than -2.5).
  11. I think words fail me as far as the fraudsters are concerned who "sell stars" to people who are bereaved like the friend of Hobbes in the post above. Taking advantage in this way of people at their most vulnerable is the lowest of the low, and brings our discipline into ill repute. None of these "names" are recognised by anyone, especially not the IAU, which is the only body with the official responsibility for naming astronomical objects. For all I know, these companies probably "sell" the same star again and again and again, and the crassness of "selling" a magnitude 19 star which would require a professional telescope to image is obvious. It reminds of a similar scam involving selling "real estate" on the Moon. The more vocal the Astronomy community is about this scam, the fewer people will be taken in by these con artists.
  12. i think organisations and individuals who pollute the sky with ridiculous amounts of light should pay a "light pollution tax". 95% of the time it is completely unnecessary with floodlights and security lights sending most of their energy upwards or sideways instead of down. Retail parks and sports grounds are the worst culprits. Why can't they rig up the streetlights so that after midnight, two of every three lights is switched off, with the "on light" randomly alternating to deter criminals? This is the 21st century after all! As someone who is interested both in Astronomy and what is left of our wild places in England, I am deeply concerned about plans to increase the population of this country to more than 70 million. This island is overcrowded and creaking at the seams - travelling on the M6 yesterday between Birmingham and Cheshire I was in congestion for about 40 miles, and yet this was a Sunday with hardly any trucks on the road! It seems the encroachment of urban Britain into my beloved rural England can't be stopped. I suspect in a few decades, you would have to travel to the north of Scotland to see a dark sky.
  13. This is on my "before I die" Astronomy wish list as well, along with a Supernova (within the Milky Way), the first human's on Mars and the discovery of life outside the Solar System. Probably the comet is the most likely of those 4 things to actually happen!
  14. I often think of red supergiants being more like seething red hot nebulae than stars. Certainly if you saw one up close (or at least from a safe distance!) it wouldn't look at all sun-like. They don't have a well-defined photosphere, and are probably not even vaguely spherical as the outer layers swell in and out of hydrostatic equilibrium.
  15. As far as I can think (I'm sure someone will correct me), there are only three unambiguously female constellations - Virgo, Andromeda and Cassiopeia. Where as the skies are littered with male heroes like Orion, Perseus and Hercules, all the ladies have got is a virgin, a damsel-in-distress, and a foolish queen who boasted of her daughter's beauty. Obviously, the constellations names need reviewing with regards to equal opportunities. Come to think of it, perhaps Draco is female as well. I'm sure it was named after my mother-in-law!
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