{"id":5439,"date":"2013-09-20T16:40:09","date_gmt":"2013-09-20T20:40:09","guid":{"rendered":"http:\/\/spinor.info\/weblog\/?p=5439"},"modified":"2013-09-20T23:19:22","modified_gmt":"2013-09-21T03:19:22","slug":"interstellar-voyager","status":"publish","type":"post","link":"https:\/\/spinor.info\/weblog\/?p=5439","title":{"rendered":"Interstellar Voyager"},"content":{"rendered":"

\"\"<\/a>Last week, it was all over the news: Voyager 1 has left the solar system.<\/p>\n

Except that it really didn’t. Voyager 1’s trajectory is, and will continue to be, dominated by the Sun’s gravity for thousands of years. Voyager 1 is significantly closer to the Sun than Sedna (one of the icy dwarfs in the outer solar system) at aphelion. And then there is the hypothesized Oort cloud, a spherical cloud of planetesimals roughly a light year from the Sun. Voyager 1 will take thousands of years to travel that distance.<\/p>\n

Of course, Voyager 1 is way outside the orbit of the outermost planet, Neptune. But that happened decades ago, back in the 1980s. By 1990, Voyager 1 was far enough from the Sun to be able to take its famous “family portrait”, a mosaic that covered six of the eight planets (Mars was too faint, while Mercury was too close to the Sun.)<\/p>\n

So what exactly happened this month? Well, Voyager 1 crossed the heliopause, the boundary where the solar wind collides with the interstellar medium. It is also the location where magnetic fields are no longer dominated by the Sun.<\/p>\n

So in this sense, Voyager 1 has indeed crossed into the interstellar medium. The particles its instruments sample are the particles found in interstellar space, not particles emitted by the Sun.<\/p>\n

So it is a significant milestone, but it is somewhat misleading to suggest that “Voyager 1 has left the solar system”, which we heard so many times in the past several days.<\/p>\n<\/fb:like>","protected":false},"excerpt":{"rendered":"

Last week, it was all over the news: Voyager 1 has left the solar system. Except that it really didn’t. Voyager 1’s trajectory is, and will continue to be, dominated by the Sun’s gravity for thousands of years. Voyager 1 is significantly closer to the Sun than Sedna (one of the icy dwarfs in the […]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-5439","post","type-post","status-publish","format-standard","hentry","category-space","category-26-id","post-seq-1","post-parity-odd","meta-position-corners","fix"],"_links":{"self":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts\/5439","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5439"}],"version-history":[{"count":2,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts\/5439\/revisions"}],"predecessor-version":[{"id":5442,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts\/5439\/revisions\/5442"}],"wp:attachment":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5439"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5439"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5439"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}