{"id":5672,"date":"2015-08-17T16:17:16","date_gmt":"2015-08-17T16:17:16","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=5672"},"modified":"2015-08-17T16:17:16","modified_gmt":"2015-08-17T16:17:16","slug":"rosettas-big-day-in-the-sun","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/rosettas-big-day-in-the-sun\/","title":{"rendered":"Rosetta’s big day in the Sun"},"content":{"rendered":"
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\"Comet
<\/span><\/a><\/span> Comet southern hemisphere<\/span><\/figcaption><\/figure>\n

ESA\u2019s Rosetta today witnessed Comet 67P\/Churyumov\u2013Gerasimenko making its closest approach to the Sun. The exact moment of perihelion occurred at 02:03 GMT this morning when the comet came within 186 million km of the Sun.<\/span><\/p>\n

In the year that has passed since Rosetta arrived, the comet has travelled some 750 million kilometres along its orbit towards the Sun, the increasing solar radiation heating up the nucleus and causing its frozen ices to escape as gas and stream out into space at an ever greater rate. These gases, and the dust particles that they drag along, build up the comet\u2019s atmosphere \u2013 coma \u2013 and tail.<\/span><\/p>\n<\/div>\n

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The activity reaches its peak intensity around perihelion and in the weeks that follow \u2013 and is clearly visible in the spectacular images returned by the spacecraft in the last months. One image taken by Rosetta\u2019s navigation camera was acquired at 01:04 GMT, just an hour before the moment of perihelion, from a distance of around 327 km.<\/span><\/div>\n<\/div>\n<\/div>\n

The scientific camera is also taking images today \u2013 the most recent available image was taken at 23:31 GMT on 12 August, just a few hours before perihelion. The comet\u2019s activity is clearly seen in the images, with a multitude of jets stemming from the nucleus, including one outburst captured in an image taken at 17:35 GMT yesterday.<\/span><\/p>\n

\u201cActivity will remain high like this for many weeks, and we\u2019re certainly looking forward to seeing how many more jets and outburst events we catch in the act, as we have already witnessed in the last few weeks,\u201d says Nicolas Altobelli, acting Rosetta project scientist.<\/span><\/p>\n<\/div>\n

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Rosetta\u2019s measurements suggest the comet is spewing up to 300 kg of water vapour \u2013 roughly the equivalent of two bathtubs \u2013 every second. This is a thousand times more than was observed this time last year when Rosetta first approached the comet. Then, it recorded an outflow rate of just 300 g per second, equivalent to two small glasses of water.<\/span><\/p>\n

Along with gas, the nucleus is also estimated to be shedding up to 1000 kg of dust per second, creating dangerous working conditions for Rosetta.<\/span><\/p>\n

\u201cIn recent days, we have been forced to move even further away from the comet. We\u2019re currently at a distance of between 325 km and 340 km this week, in a region where Rosetta\u2019s startrackers can operate without being confused by excessive dust levels \u2013 without them working properly, Rosetta can\u2019t position itself in space,\u201d comments Sylvain Lodiot, ESA\u2019s spacecraft operations manager.<\/span><\/p>\n<\/div>\n

Monitoring the comet\u2019s changing environment in the lead up to, during and after perihelion is one of the primary long-term science goals of the mission.<\/span><\/div>\n
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Over the last few months, seasons on the comet have changed, throwing its southern hemisphere into a short \u2013 about 10 month \u2013 summer after more than five-and-a-half years in darkness. This has revealed parts of the surface that have previously been cast in shadow during Rosetta\u2019s sojourn at the comet, allowing scientists to fill in some of the missing pieces of its regional map.<\/span><\/p>\n

They have now identified four new geological regions on the southern hemisphere, which includes parts of both comet lobes, bringing the total number of regions to 23. The names of the new regions follow the naming convention of Egyptian gods and goddesses adopted for the comet: Anhur, Khonsu, Sobek and Wosret.<\/span><\/p>\n<\/div>\n

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The comet\u2019s average temperature has also been on the increase. Not long after arriving, surface temperatures of around \u201370\u00baC were recorded. By April\u2013May 2015, this had risen to only a few degrees below zero celsius, and now highs of a few tens of degrees above zero are forecast for the next month.<\/span><\/div>\n<\/div>\n<\/div>\n

Meanwhile, astronomers back on Earth have been following the comet\u2019s evolution from afar. Rosetta is far too close to the comet to see its growing tail, but images collected over the past few months with telescopes across the world show that it already extends more than 120 000 km.<\/span><\/p>\n<\/div>\n

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A\u00a0lop-sided coma, with a notable high-density region away from the main\u00a0tail, was revealed in various images, including some\u00a0taken last week\u00a0from the Gemini-North telescope on Mauna Kea, Hawaii.<\/span><\/div>\n<\/div>\n

\u201cCombining these big-picture views from ground-based telescopes with Rosetta\u2019s close-up study of individual jets and outbursts will help us to understand the processes at work on the comet\u2019s surface as it approaches the Sun,\u201d adds Nicolas.<\/span><\/p>\n<\/div>\n

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\u201cWe aim to go back in much closer again after the activity subsides and make a survey of how the comet has changed. We also continue to hope that Philae will be able to resume its scientific operations on the surface and give us a detailed look at changes which may be occurring immediately surrounding its landing site.\u201d<\/span><\/div>\n<\/div>\n

Finally, Patrick Martin, ESA\u2019s Rosetta mission manager remarks: \u201cIt\u2019s exciting to reach the milestone of perihelion, and we look forward to seeing how this amazing comet behaves as we move away from the Sun with it over the coming year.\u201d<\/span><\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

ESA\u2019s Rosetta today witnessed Comet 67P\/Churyumov\u2013Gerasimenko making its closest approach to the Sun. The exact moment of perihelion occurred at 02:03 GMT this morning when the comet came within 186 million km of the Sun. In the year that has passed since Rosetta arrived, the comet has travelled some 750 million kilometres along its orbit […]<\/p>\n","protected":false},"author":2,"featured_media":5668,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[38,17,20],"tags":[],"class_list":["post-5672","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-curiosity","category-research","category-space-news"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large-300x100.jpg",300,100,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",600,202,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",600,202,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",550,185,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",95,32,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",625,210,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",96,32,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/08\/Comet_southern_hemisphere_large.jpg",150,50,false]},"author_info":{"info":["RevoScience"]},"category_info":"Curiosity<\/a> Research<\/a> Space\/ AstroPhysics<\/a>","tag_info":"Space\/ AstroPhysics","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/5672","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=5672"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/5672\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/5668"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=5672"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=5672"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=5672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}