*********************************** The SOCIETY for POPULAR ASTRONOMY *********************************** ==================================================== Electronic News Bulletin No. 260 2009 February 1 ==================================================== Here is the latest round-up of news from the Society for Popular Astronomy. The SPA is Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/ JANUARY FIREBALLS By Alastair McBeath, SPA Meteor Section Director Sightings of the January 9-10, ~18:47 UT fireball over to off western Britain discussed in the previous ENB, have now risen to ten, the observers scattered over Lancashire, Derbyshire and Staffordshire, east to York and Nottingham, and south to Hereford and Gwent. Unfortunately, the rough proposed atmospheric track suggested last time has not been improved upon, as too few people managed to give accurate sky-positions for the meteor. It is possible though the start was somewhat east of the northwest or central-western Wales area indicated initially, so maybe high above north to north-central Wales instead. The concentration of observers in northwest England seems to have resulted thanks to Venus, as from here, the fireball was seen not far from that brilliant planet. After this, there seems to have been quite a clutch of fireballs generally around January 17 and 18. French meteor expert Karl Antier mentioned a spectacular magnitude -14 event widely-reported from France on January 17 at 17:50 UT, followed just over an hour later by a superb, brilliant fireball seen and imaged across much of northern Europe from the Netherlands east to Poland and north into Scandinavia, at 19:08 UT. Assistant Meteor Director David Entwistle's SPA Forum posting at http://snipurl.com/b2poc has more details on the latter event, including links to commentaries and some of the images. Neither of these has been reported from UK sites as yet. However, UK reports of two more modest fireballs, both from single observers so far, have come in from the next night, January 18-19, around 17:40 (from Suffolk; magnitude about -4) and 22:34 UT (Gloucestershire; magnitude range -3/-6), as noted on our Recent Fireball Sightings webpage, at http://snipurl.com/b2psv . There is nothing so far to link any of these fireballs with one another, so the apparent "clustering" effect was probably just coincidence. All additional observations of these or other fireballs (any meteors reaching at least magnitude -3) from the British Isles and nearby would be welcomed by the Meteor Section. Advice on what to send and where to is on the "Fireball Observing" page of the SPA website, at: http://snipurl.com/b2pvo . CURIOUS ASTEROID NEARBY Spaceweather.com Newly-discovered asteroid 2009 BD passed slowly by the Earth on January 25 at a distance of only 400,000 miles. It is approximately 10 metres across and poses no significant threat, but it merits attention because its orbit appears to be almost identical to that of the Earth. 2009 BD may be a rare 'co-orbital asteroid', circling the Sun in near-tandem with our planet. If current determinations of its orbit are correct, 2009 BD will remain in our neighbourhood for many months and possibly years to come. METHANE DETECTED ON MARS NASA Scientists who used the infrared and Keck telescopes in Hawaii have belatedly reported the detection of methane in the atmosphere of Mars in 2003. Methane could be expected to be destroyed in the Martian atmosphere in a variety of ways, so the apparent existence of plumes of methane on Mars indicated that some recently operating process was releasing the gas. The reported plumes were seen over areas that show evidence of ancient ground ice or flowing water, including a part of Syrtis Major, an ancient volcano about 1200 km across. Of course 'astrobiologists' are seizing on the detection, because much of the methane formed on the Earth comes from flatulent cows. Even the most optimistic enthusiasts for extra-terrestrial life, however, hardly expect an immediately analogous source to operate on Mars, and in fact there are purely geological processes that create methane, such as the conversion of iron oxide into the serpentine group of minerals, a process that could proceed on Mars. Although no evidence has been seen of active vulcanism on Mars today, ancient methane that has been combined with ice in a crystalline structure called methane clathrate might be released now. One method that might distinguish whether life produced the methane is measurement of isotope ratios: isotopes of an element have slightly different chemical properties, and life prefers to use the lighter isotopes. Methane and water released on Mars should show distinctive ratios for isotopes of hydrogen and carbon if life were responsible for methane production. It remains for future in-situ measurements to try to determine the origin of the Martian methane. TRANSIT SEARCH FINDS SUPER-NEPTUNE Harvard-Smithsonian Center for Astrophysics Astronomers have discovered a planet somewhat larger and more massive than Neptune orbiting a star 120 light-years from Earth. While Neptune has a diameter 3.8 times that of Earth and a mass 17 times the Earth's, the new-found object, named HAT-P-11b, is 4.7 times the size of Earth and has 25 Earth masses. HAT-P-11b was discovered because it transits in front of its parent star, thereby blocking about 0.4% of the star's light. A network of small automated telescopes known as HATNet detected the slight periodic dimming. The object is in the constellation Cygnus; it is the 11th extra-solar planet found by HATNet, and the smallest yet discovered by any of the several transit search projects that are currently in operation. The amount of dimming during a transit tells the astronomers how big the planet must be, and accurate measurements of the star's radial velocity allow an estimate to be made of the mass of a transiting planet. A number of Neptune-like planets has been found recently by radial- velocity searches, but HAT-P-11b is only the second Neptune-like planet that has been found to transit its star and thus to permit the determination of its mass and radius. It orbits very close to its star, revolving once every 4.88 days. The star itself is about 75% the size of our Sun and somewhat cooler. There are signs of a second planet in the HAT-P-11 system, but more radial-velocity data are needed to confirm that. Another team has located one other transiting super-Neptune, known as GJ436b, around a different star. It was discovered by a radial-velocity search and later found to show transits. R CORONAE BOREALIS IAU The yellow supergiant star R Coronae Borealis is the prototype of a class of variable stars, which fade by several magnitudes at irregular intervals. It normally shines at approximately magnitude 6, just about visible to the naked eye in non-polluted skies, but at random intervals ranging from several months to many years fades to as faint as magnitude 14. Over successive months it gradually regains its normal brightness. The cause of that behaviour is the emission of a great cloud of carbon dust, in fact soot, from the star's atmosphere. If the cloud is ejected on our side of the star it can block some or all of the visible light from our sight. The star never disappears altogether, but its light can be reduced more than a thousandfold, and what little is left does not have the normal spectrum; it probably does not come from the hot surface of the star but from some outer regions, in rather the same way as the Sun does not disappear completely during a total solar eclipse but is left with its corona still visible. In recent months the star has been fainter than magnitude 14.0, near or at its historic minimum. It began its current fading episode around 2007 July 6 it had faded to 12.0 by 2007 August 12, reached 14th magnitude about the end of that year and has continued gently to fade further ever since. The duration of the current episode and its depth are similar to that observed during the previous extreme fading episode that began around 1963 June and continued (with only one brief interruption) until about 1965 December, when it faded to about magnitude 14.5. PLANET WITH WILD TEMPERATURE SWINGS NASA/JPL The Spitzer space telescope has observed a planet that heats up to red-hot temperatures in a matter of hours before quickly cooling again. The planet is a gas giant that was discovered in 2001; it is in a 111-day orbit around the star HD 80606, an otherwise undistinguished star in the constellation Ursa Major, 190 light-years away. The orbit is very eccentric, taking the planet nearly as far out as the Earth is from our Sun, and much closer in than Mercury. HD 80606b spends most of its time relatively far from its star, and traverses the closest part of its orbit in less than a day. Spitzer observed HD 80606b before, during and just after its close passage past the star in 2007 November, as the planet baked in the star's heat. In just six hours, its temperature rose from 800 to 1,500 Kelvin. Astronomers did not know whether the planet would disappear completely behind the star, an event called a secondary eclipse, or whether it would remain in view. Luckily for the observing team, it did temporarily disappear from view, enabling its initial and final temperatures to be estimated (had it had not been eclipsed, the team would have known only the temperature change without knowing the starting point). The extreme temperature swing observed by Spitzer indicates that the 'air' near the planet's gaseous surface must quickly absorb and lose heat. Such atmospheric information about how a planet responds to sudden changes in heating -- an extreme version of seasonal change -- had not previously been obtained for a planet orbiting another star. A key factor in being able to make the observations is the planet's eccentric orbit. Unlike so-called 'hot Jupiter' planets that are in tight orbits around their stars, HD 80606b rotates on its axis roughly every 34 hours. Hot Jupiters, on the other hand, are thought to be tidally locked like our Moon, so one side always faces their stars. Because HD 80606b spins on its axis many times per orbit, the astronomers were able to measure how its atmosphere responds to being baked by the star. ESA EXPECTS BUSY YEAR IN SPACE BBC News Last year the European space agency delivered the 'Columbus' module to the international space station, and flew its space freighter, the ATV, there for the first time; the cargo ship will become the main way of re-supplying the ISS when the US shuttle fleet is retired. ESA activity this year will include the recruitment of new astronauts and the first launches by the Russian Soyuz rockets from the European space-port at Kourou in French Guiana. At least half of all ESA missions will be launched on Soyuz. The anticipated events include the launching in the spring, both together on an Ariane 5, of the 'Herschel' infrared telescope and 'Planck', which will study the cosmic microwave background radiation; there will also be Earth-observation satellites concerned with ice, soil, and gravity, and 'Vega', the newest European rocket, which will be used for smaller payloads. THOMAS HARRIOT: A TELESCOPIC ASTRONOMER BEFORE GALILEO RAS This year the world celebrates the International Year of Astronomy (IYA2009), marking the 400th anniversary of the first drawings of celestial objects through a telescope. They have long been attributed to Galileo Galilei, but astronomers and historians in the UK are keen to promote a lesser-known figure, English polymath Thomas Harriot, who made the first drawing of the Moon through a telescope several months earlier, in 1609 July. Harriot not only preceded Galileo but went on to make lunar maps that would not be bettered for decades. Harriot lived from 1560 to 1621. By 1609, he had acquired his first 'Dutch trunke' (telescope). He turned it towards the Moon on July 26, becoming the first astronomer to draw an astronomical object as seen through a telescope. His crude sketch shows a rough outline of the lunar terminator (the line marking the division between night and day on the Moon) and includes a handful of features like the dark areas Mare Crisium, Mare Tranquillitatis and Mare Foecunditatis. Harriot went on to produce further maps from 1610 to 1613. Not all of them are dated, but they show an increasing level of detail. By 1613 he had created two maps of the whole Moon, with many identifiable features such as lunar craters depicted in their correct relative positions. His work seems all the more impressive when one realises that the earliest telescopes, of the kind used by Harriot (and Galileo), had narrow fields of view, so only a small portion of the Moon could be seen at any one time. Despite his innovative work, Harriot remains relatively unknown because, unlike Galileo, he did not publish his drawings. Bulletin compiled by Clive Down (c) 2009 the Society for Popular Astronomy The Society for Popular Astronomy has been helping beginners to amateur astronomy -- and more experienced observers -- for more than 50 years. If you are not a member then you may be missing something. Membership rates are extremely reasonable, starting at just £16 a year in the UK. You will receive our bright quarterly magazine Popular Astronomy, regular printed News Circulars, help and advice in pursuing your hobby, the chance to hear top astronomers at our regular meetings, and other benefits. The best news is that you can join online right now with a credit card or debit card at our lively website: http://www.popastro.com/