Institute of Astronomy PUBLIC OPEN EVENING outreach — 20 December 2017 — A A Solar System to rival our own TONIGHT’S SPEAKER

Mihkel Kama Visit the menagerie of extreme worlds! Our weekly welcome The Kepler-90 planets (top) and our own solar system (bottom). Planet sizes are to scale but ELCOME to our weekly public distances are not. Credit: NASA/Ames Research Center/Wendy Stenzel Wopen evenings for the 2017/18 ASTRONOMERS have announced the The discovery was made using the season. Each night there will be a discovery of the first star to host as Kepler Space Telescope and a type of half-hour talk which begins promptly many planets as our own Solar System. artificial intelligence called machine at 7.15pm: tonight Mihkel Kama will Kepler-90 is a star some 2,500 light- learning to mine the data for planets be letting us visit the menagerie of years away from Earth. A little hotter that were missed by previous searches. extreme worlds! and larger than the Sun, Kepler-90 was Kepler-90’s planetary system The talk is followed by an oppor- known to have seven planets around appears to be ordered in a similar way tunity to observe if (and only if!) the it. But now an eighth has been found to our own – the inner planets are weather is clear. The IoA’s historical – small enough to be rocky, and much small while the outer planets are large. further in than the others, the planet Everything is scrunched much tighter, Northumberland and Thorrowgood completes a circuit of the star every however, with all eight planets packed telescopes, along with our modern 14.4 days. It likely has a scorching hot within the distance between the Earth 16-inch telescope, will be open surface temperature of around 425°C. and the Sun. for observations. In addition, the Cambridge Astronomical Association strings of letters and numbers indicat- will provide a floorshow outdoors on 86 new star names ing their position or ordering. The IAU the Observatory lawns, relaying live committee reviews the names of the images from their telescopes and from around the brightest and most interesting stars, providing a commentary. If we’re un- world some of which have accumulated doz- lucky and it’s cloudy, we’ll offer you a ens of names and spelling variations conciliatory cup of tea after the talk THE International Astronomical Un- over the years. (with perhaps some more astro-in- ion (IAU) has formally approved new For example, the names Xamidi- formation in the lecture theatre for names for 86 stars. mura and Pipirima were approved for those who want to stay on). Traditionally, most star names in components of the bright binary stars use today have Arabic, Greek, or Latin Mu-1 and Mu-2 in the constellation of hanks to everyone who’s been origins. The 86 new names are drawn Scorpius, respectively. Xamidimura re- coming along this term – despite from those used for individual stars by fers to the xami di mura -- “eyes of the T other cultures, namely Australian Abo- lion,” a nickname for the binary among what must rank as the worst term riginal, Chinese, Coptic, Hindu, Mayan, the Khoikhoi people of South Africa. weather-wise in many years! This is Polynesian, and South African. Pipirima refers to inseparable mytho- our last open evening of the year; Modern star catalogues contain logical twins from a Tahitian legend: a we’re now going to take a break over millions or even billions of objects, boy and a girl who ran away from their Christmas and New Year, returning most of which are identified only by parents and became stars in the sky. on 10th January 2018.

@cambridge_astro facebook.com/InstituteOfAstronomy 2 — IOA PUBLIC OPEN EVENING — 20 December 2017

The most comprehensive map of the Hubble’s celestial southern sky released online snow globe ASTRONOMERS at the Australian The map of the southern sky is National University (ANU) have created available through an online portal at the most comprehensive map of the skymapper.anu.edu.au/sky-viewer. southern sky so far and made it public- A search bar enables viewers to ly available to view online. locate well known objects in the south- The survey includes about 70,000 ern sky with astronomical coordinates individual images, capturing nearly or common names, such as Eta Carinae 300 million stars and galaxies. It was or NGC 253 (also known as the Sculp- created using SkyMapper, a 1.3-metre tor Galaxy). telescope at the ANU Siding Spring Ob- servatory that is creating a full record of the southern sky. What has been released so far is only the beginning of a five-year programme to capture the southern sky in all its The Hubble Space Telescope’s view of the splendour. When finished, the final re- globular Cluster M79. Credit: NASA/ ESA lease will show stars and galaxies that are up to 50 times fainter than the cur- The Hubble Space Telescope has taken rent version (or a million times fainter this image of a blizzard of stars – than visible to the unaided human eye resembling a swirling snowstorm in a on a dark night). snow globe. The SkyMapper telescope. Credit: ANU The stars make up the globular star cluster Messier 79 (or M79) located 41,000 light-years from Earth. About ‘Oumuamua checked for alien tech 150,000 stars are packed into a volume only 118 light-years across. These giant highly unusual structure for an asteroid “star-globes” contain some of the oldest Artist’s impression of the interstellar – an elongated cigar shape, hundreds stars in our galaxy, estimated to be 11.7 of metres in length but with width and asteroid ‘Oumuamua’. billion years old. height perhaps only one tenth as long. In the image, Sun-like stars appear Researchers working on long-dis- yellow, reddish stars are bright giants tance space transportation have that represent the final stages of a star’s previously suggested that a cigar or life and most of the bright blue stars needle shape is the most likely archi- have exhausted their hydrogen fuel and

Credit: ESO/M. Kornmesser Credit: tecture for an interstellar spacecraft, are now fusing helium in their cores. since this would minimise friction and Most globular clusters are grouped Breakthrough Listen, the global as- damage from interstellar gas and dust. around the central hub of our galaxy. tronomical programme searching for While a natural origin is more likely, Exceptionally, M79 is nearly on the op- evidence of civilizations beyond Earth, Breakthrough Listen (observing in four posite side of the sky from the direction is currently focusing its observational radio wavebands) is well positioned to of the galactic centre. One idea behind efforts on ‘Oumuamua, the mysterious explore the possibility that ‘Oumuamua the cluster’s unusual location is that its interloper recently spotted moving could be an artefact. First results have neighbourhood may contain a high- rapidly through the solar system. failed to find artificial signals from the er-than-average density of stars, which ‘Oumuamua was discovered in object, but the large amount of data fuelled its formation. Another possibil- October 2017, passing Earth at about collected means that a full analysis will ity is that M79 may have formed in an 85 times the distance to the Moon – a take some time to complete. unusual dwarf galaxy that is merging stone’s throw, in astronomical terms. Even if no evidence of extraterres- with the Milky Way. It is the first object discovered in the trial technology is heard, the observa- solar system that appears to originate tions will cover portions of the radio from another star system. Its high spectrum in which the object has not Joke of the Week speed – over 300,000 km/h at its peak – yet been observed, and could provide suggests it is not gravitationally bound important information about the possi- What do you get if you cross Santa Claus with to the Sun, but will continue its voyage bility of water/ice, or the chemistry of a a space ship? back into interstellar space. It has a coma (gaseous envelope). A u-f-ho-ho-ho!