InstItute of Astronomy PublIc Open evenIngs WeDNESDAy 21st oCTOBER 2009 As I write this it’s raining outside. Must be a Wednesday... Whatever the weather, welcome to our winter season of public open evenings, which will now run till the end of March next year. There will be a 30 minute talk starting promptly at 7.15pm, followed by an opportunity to observe with both modern and historical telescopes if and only if the weather is clear. The talk schedule for the coming term can be found at : http://www.ast.cam.ac.uk/public/public_observing/0910/timetable.html If you have any questions, suggestions or comments about the IoA Open Evenings please get in touch with CAROLIN CRAWFORD [email protected] THIS WEEK’S TALK : Anna Quider is examining The Dusty Universe NEXT WEEK is slightly different : We are doing two special open evenings during half-term, on our usual Wednesday (28th Oct) and also on the Thursday (29th Oct) as part of the national International Year of Astronomy MOONWATCH. The talk on both evenings will be Carolin Crawford wondering Will we return to the Moon?, hopefully followed by observing sessions dedicated to observing the Moon. YET MORE EXOPLANETS! There’s been a large increase in the number of known exoplanets (ie ‘extra- solar’ planets, orbiting stars other than our own) this week, with no less than a further 32 being announced on Monday at an international conference. These were all found by a method which searches for the signature of a miniscule ‘wobble’ in the star’s motion due to the tug of gravity from a planet in orbit around it. The exoplanets themselves are too small and faint to image directly (it’s just an artist’s impression shown to the right!). The wobble technique is most sensitive to very massive planets in orbit very close to their star; however, the observations and instrumentation are increasingly sensitive to lower-mass planets. A surprising number of the new exoplanets announced are what are known as ‘super-Earths’ - with a mass of only several times that of the Earth, they lie at the lower end of the mass scale of known exoplanets. Several live within multi-planet stellar systems, but any planets that closely resemble Earth as yet remain elusive. This week’s announcement brings the grand total of known exoplanets to 403, and we can expect many more to be discovered over the next year. A STRANDED SPIRIT ON MARS The Mars rover Spirit has been caught fast in soft sand for the last five months, preventing it from continuing its exploration of the surface of Mars. Back here on Earth, the operations team has spent the time carefully assessing how best to extract it from the mire – including Help! tests that directly mimic the conditions using a model rover trapped in sandbox. A decision will soon be made as to the best way to try and steer it free, probably in early November sometime. Not that it’s remained idle while stuck in one place – it’s kept busy analysing the soil of its immediate environment. Meanwhile its counterpart Opportunity is still roaming around the other side of Mars, and has discovered a third large iron/nickel meteorite in about as many months, during its long trek across the wide open desert on the way to have a look at the large crater Endeavour. If you’re an armchair astronaut and fancy exploring the surface of Mars yourself, why not try GOOGLE MARS? Maps of elevation or the visible/infrared view of the planet, with mountains, dunes, craters, spacecraft landing spots etc all labelled, with links to images and relevant press releases. Just what you need for entertainment on a wet Wednesday evening... SKY MAP FOR 8PM ON THE 21ST OCTOBER courtesy of http://www.heavens-above.com/ SO WHAT’S IN THE SKY THIS WEEK? o The MOON is currently a very young crescent appearing at sunset, and setting by 7pm. It’ll swell to a half-moon by the start of next week, rising a little later each day in ready to grace our skies ready for the MoonWatch events. o JUPITER is prominent as the brightest ‘star’ in the sky low down to the South. It’s easy to identify as it’ll be slightly to the upper left of the Moon on the 26th (next Monday evening) and to the lower right of the Moon the following evening. o For what it’s worth, the ORIONID METEOR SHOWER is due to reach a peak this evening. Most of the meteors don’t really start till after midnight, but given it’s a moonless night, keep your eye out for any early shooting stars this evening. The show is created by tiny pieces of debris left behind in the trail of Halley’s comet, burning up in our atmosphere. o VENUS, although very bright in our morning skies is rapidly moving towards to the Sun, and thus lower down in our skies – it will soon no longer be observable. But if you have a clear view of the Eastern horizon early in the morning, it’s worth looking for. The last vestige we have of the summer night sky is the SUMMER TRIANGLE, still visible in the early evenings as it sets to the South-West. This is a large, and almost right-angled triangle on the sky formed by the three brightest stars in the constellations of Cygnus (the swan), Lyra (the scales) and Aquila (the eagle): these are called Deneb, Vega and Altair respectively. The triangle is easy to spot as the 3 stars will be amongst the first to emerge in the evening twilight. Once you find the Summer Triangle it’s easy to identify the line of the Milky Way, which passes through the middle of the triangle, following the line of Cygnus. It might just be worth looking out for, in the absence of the bright Moon (and hopefully, clouds...) this week. Look out for some IRIDIUM FLASHES over the next week if you can – caused by sunlight reflected from the solar panels of satellites. The ones in italics should be the brightest. Look at the direction/altitude given at the day/time given and see if you can see one – but note these times are for Cambridge – if you live a few miles away you need to look up the correct viewing details for your location at http://www.heavens-above.com/ Date Time Altitude Direction Date Time Altitude Direction 23 Oct 18:06:08 40° SSW 25 Oct 18:34:19 42° NNE 24 Oct 18:00:07 39° SW 26 Oct 18:28:09 44° NNE 24 Oct 19:40:29 41° NNE 27 Oct 18:21:59 46° NNE ST JOHN’S COLLEGE LIBRARY ARE CELEBRATING ASTRONOMY St John’s library will be holding an exhibition celebrating the contributions made to Astronomy by the College over the years. The displays include medieval manuscripts, 18th century astronomical instruments, archival photographs, and the papers of Johnian astronomers, such as John Couch Adams (who played an important role in the discovery of the planet Neptune). The exhibition is open to all, and continues till the 21st December. Find out more at http://www.joh.cam.ac.uk/library/special_collections/hoyle/future_events/ 56 Andromedae is a binary star in the constellation Andromeda. Its apparent magnitude is 5.69. This binary system is composed of two yellow giants and is located near the open cluster NGC 752. NGC 752 is an open cluster in the Andromeda constellation. An object that may have been NGC 752 was described by Giovanni Batista Hodierna before 1654. It was independently discovered by Caroline Herschel in 1783 and cataloged by her brother William in 1786. NGC 752 is at a distance of 1,300 light-years away from the Solar System.[1] Upsilon Andromedae (υ Andromedae / υ And) is a binary star located approximately 44 light-years away from Earth in the constellation Andromeda. The primary star (Upsilon Andromedae A) is a yellow-white dwarf star that is somewhat younger than the Sun. The second star in the system (Upsilon Andromedae B) is a red dwarf located in a wide orbit. As of 2008, three confirmed extrasolar planets are known in orbit around the primary star. All three are likely to be Jovian planets that are comparable to Jupiter. Upsilon Andromedae was both the first multiple-planet planetary system to be discovered around a main sequence star, and the first multiple- planet system known in a multiple star system. Upsilon Andromedae A is a yellow-white dwarf of spectral type F8V, similar to our Sun but rather younger, more massive, and luminous. According to its entry in the Geneva-Copenhagen survey, the star is around 3.1 thousand million years old, and has a similar proportion of iron relative to hydrogen to the Sun.[4] At around 1.3 solar masses, it will have a shorter lifetime than our Sun. The amount of ultraviolet radiation received by any planets in the star's habitable zone would be similar to the ultraviolet flux the Earth receives from the Sun.[5] Upsilon Andromedae B is a red dwarf of spectral type M4.5V located at a distance (in the plane of the sky) of 750 AU from the primary star. The true separation between the two stars is unknown because the displacement along the line of sight between us and the Upsilon Andromedae stars is unknown, so this value is a minimum separation. It was discovered in 2002 in data collected as part of the Two Micron All Sky Survey.[6] The star is less massive and far less luminous than our Sun.