Venus passing in front of the Sun Venus is sometimes called the Earth’s twin planet. It is closest to the Earth in size and mass, and is our nearest neighbour. However, the resemblance ends there. Venus is the hottest planet in the Solar System and its surface is an extremely hostile environment. Its dense atmosphere is mainly carbon dioxide and there are several thick layers of cloud made of sulphuric acid. The atmosphere acts as a blanket, trapping incoming solar radiation and generating an average temperature of 464° Celsius – hot enough to melt lead! Missions to study the Venusian atmosphere show that this Venus Express is the European Space Agency’s first extreme greenhouse effect means there is little temperature mission to Venus. The spacecraft shares more than a variation between night and day. speedy-sounding name with Red Planet explorer, Mars Express. The basic structure of both spacecraft is identical, as is much of the scientific instrumentation. Venus Express uses copies of Mars Express sensors to study the Venusian atmosphere at different altitudes, monitor the plasma environment and to take images Venus of cloud patterns. Venus is the brightest object in the sky except for the Sun Venus is the second planet from the Sun and, when it is and Moon. The planet is often called the “morning star” or precisely aligned with the Earth, we can see it pass in front “evening star” because it is visible at dawn and dusk. of the Sun’s disk. These alignments are rare because the orbital plane of Venus is slightly tilted relative to that of Venus is named after the Roman goddess of beauty and the Earth. The Transit of Venus in 2004 was the first time in love. To the ancient Romans, Venus was the patron 121 years that the phenomenon had been visible. The next goddess of vineyards and gardens – rather ironic, given the planet’s scorched surface! As Greek transits are in 2012 and 2117. Historically, Transits influence spread, Venus was attributed with the of Venus are important because they were used to calculate characteristics of the goddess Aphrodite, whose the distance between the Earth and the Sun. The transit legendary beauty made her irresistible to gods of 1769 was the reason for Captain James Cook’s epic and mortals alike. voyage around the world which also led to a wide range of discoveries about Australia, New Zealand and the islands of the Pacific. If you would like to know more about The Science and Technology Facilities the Venus Express mission, try the Council operates world-class, large-scale following resources: research facilities; supports scientists and engineers world-wide; funds researchers in WORLD WIDE WEB SITES universities and provides strategic scientific www.esa.int/venus advice to government. Venus Express is also closely related to the www.uk2planets.org.uk The Council’s Science in Society unit offers a comet chaser, Rosetta, and uses copies of its www.mssl.ucl.ac.uk/www_plasma/ wide range of support for teachers, scientists detectors to study the Venusian magnetic field and missions/vex.html and communicators to facilitate greater the chemical composition of the planet’s atmosphere. www.nineplanets.org engagement with STFC science which includes www.esa.int/marsexpress astronomy, space science, particle physics and www.esa.int/rosetta nuclear physics: www.atm.ox.ac.uk/project/virtis www.venus.wisc.edu For schools This sharing of • Free Publications and resource guides technology meant that suitable for teaching ages 10-18. Go to www. BOOKS Venus Express could Venus Sir Patrick Moore scitech.ac.uk - Public and Schools - Schools Cassell Illustrated, 2002 and Education - Resources be developed on a • Funding schemes for projects and school rapid timescale that’s The Cambridge Photographic visits. Go to www.scitech.ac.uk - Public and unprecedented. Most Guide to the Planets Schools - Funding Frederic W Taylor Air-pressures on Venus are also extreme, averaging 92 planetary missions are • A Moon rock and meteorite loan Cambridge University Press, 2001 atmospheres. This is approximately the same pressure as developed over several scheme. Go to www.scitech.ac.uk - Public and you would experience 1 kilometre beneath the sea surface years but plans for Venus Venus Revealed Schools - Schools and Education - Loan Scheme David Grinspoon • Visits to STFC’s UK laboratories in on Earth. Express were approved Perseus Books, 1998 Cheshire, Oxfordshire and Edinburgh plus The Venusian atmosphere once contained large quantities at the end of 2002, just CERN in Geneva. Go to www.scitech.ac.uk Empire of the Sun three years before its - Public and Schools - Visits and Events of water but it is now completely dry, unlike its twin planet. John Gribbin and Simon Goodwin Venus lies 41 million kilometres closer to the Sun than Earth launch in late 2005. Constable, 1998 • Researchers in Residence. Teachers are placed in partnership with young scientists who and is in a zone that’s too hot for water to last long. Mars is Venus Express has been so successful that its original IMAGES have been trained to support the teacher, act as 78 million kilometres further away from the Sun than us and mission, which was due to last 500 days, has been role models and introduce their research. Astrium (Mars Express) has an average surface temperature of –50 degrees, so cold doubled in length to 1000 days. It is due to finish in NASA/JPL/MSSS (Mars) Go to www.researchersinresidence.ac.uk that any water is locked away as ice. However the Earth is May 2009. Venus spins very slowly – once every 243 NASA/JPL/Arizona State University For scientists positioned in what’s known, after the well-known fairytale, days – this means that even with its extended mission, (Evidence of Flow) • Communication and media training ESA courses; funding schemes and Fellowships as the “Goldilocks Zone”. Its distance from the Sun is just Venus Express will have only orbited the planet for 4 NASA/JPL/AOPP (Venus) for public engagement. Go to www.scitech. right for water to exist in liquid form – probably a necessary Venusian days. ac.uk - Public and Schools - Fellowships and condition for life to evolve. Communications Training For further information telephone 01793 442175 or email [email protected] ap with a lan m rea m gel ap Ma pe d by V isphere in t e hem he u n rn lt u e ra s th vi u ol E so et x s’ p u r n e e s V s of Venus in the iew infr al v are ob d Gl a b c d Venus has a similar interior to Earth, with a partially molten core, mantle and crust, so why does it not have a similar Venus has a complex atmosphere with distinct layers and magnetic field? It had one for a billion years, generated by turbulent weather systems. There is a thick cloud layer convection currents in the core, driven by left over heat after of sulphuric acid droplets concealing lower patchy cloud Venus’s formation. When that energy ran out 3.5 billion years cover, similar to cumulus clouds on Earth. Venus Express is using infrared wavelengths to penetrate the outer layers ago, the field disappeared. This didn’t happen on Earth. Venus’s thick cloudy atmosphere means it is difficult to see (a) A false colour mosaic of the Venusian and map the whole atmosphere. surface, composed from about 1000 The reason for this is a mystery, but the lack of a magnetic the surface using normal cameras. Between 1990 and 1994, individual Venus Monitoring Camera (VMC) field means that Venus is unprotected from the Solar Wind. the Magellan spacecraft orbited Venus and used radar to Clouds on Venus move at about 350 km/h and the whole images taken in April and August 2007. atmosphere rotates 60 times faster than the planet itself! This stream of electrically charged particles hits the upper map the planet’s surface. (b) This composite image of Venus is a combination Venus Express is measuring atmospheric temperature layers of Venus’s atmosphere, colliding with atoms and This showed two large continents and other highland of ultraviolet images obtained by the Venus differences as air moves round the planet and through Monitoring Camera (VMC) and infrared images obtained molecules and carrying them into space. plateaux, separated by lowland areas where liquid may different altitudes. It is also measuring concentrations of by the Visual and Infrared Thermal Mapping Spectrometer (VIRTIS) once have flowed. There are four mountain ranges and on board ESA’s Venus Express. UCL’s Mullard Space Science Laboratory and STFC’s Rutherford sulphuric acid, sulphur dioxide and other chemicals. Appleton Laboratory have helped develop the ASPERA-4 numerous volcanoes, plus areas of broken terrain called (c) Infrared views of south polar double-vortex “tessera” that suggest Venus’s surface is moving. instrument which is investigating these interactions and VENUS’S ATMOSPHERE (d) While Earth has a planetary magnetic field, which can deviate the flow of solar the rate at which atmospheric gases are stripped away. Venus has a thick crust, which prevents continental drift, wind, Venus (and Mars) don’t. Gases in the upper atmospheres of these planets Scientists from Imperial College London have helped build so the cracking and buckling found must be caused by 96% CARBON DIOXIDE are ionised, and can thus interact with the solar wind. the magnetometer that is studying the weak magnetic different processes to the Earth’s plate tectonics. 3% NITROGEN effects produced where the Solar Wind meets the planet’s Previous missions have found giant vortices, like Venus like Earth, shows relatively few impact craters, atmosphere.