--- title: A Giant Hydrogen Cloud Is Heading Toward the Milky Way description: Scientists call it "monstrous" canonical: https://time.com/4199809/hydrogen-cloud-milky-way/ author: Maya Rhodan article:opinion: false article:content_tier: free article:published_time: 2016-01-29T16:15:56.000Z article:modified_time: 2026-02-22T14:34:30.775Z article:section: Science og:title: A Giant Hydrogen Cloud Is Heading Toward the Milky Way og:description: The vast, invisible cloud is expected to reach the Milky Way in 30 million years og:url: https://time.com/4199809/hydrogen-cloud-milky-way/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltc3d2cb515d98041c/69887b45524fc03903df6841/smith-cloud1.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 1200 og:image:height: 675 og:image:alt: smith-cloud og:type: article twitter:card: summary_large_image twitter:title: A Giant Hydrogen Cloud Is Heading Toward the Milky Way twitter:description: The vast, invisible cloud is expected to reach the Milky Way in 30 million years twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltc3d2cb515d98041c/69887b45524fc03903df6841/smith-cloud1.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # A Giant Hydrogen Cloud Is Heading Toward the Milky Way by [Maya Rhodan](https://time.com/author/maya-rhodan/) ## Maya Rhodan Jan 29, 2016 4:15 PM UTC  This composite image shows the size and location of the Smith Cloud on the sky. This composite image shows the size and location of the Smith Cloud on the sky.Z. Levay—NASA/ESA by [Maya Rhodan](https://time.com/author/maya-rhodan/) ## Maya Rhodan Jan 29, 2016 4:15 PM UTC A vast formation of hydrogen gas is heading toward the Milky Way galaxy, astronomers from the [Hubble Space Telescope](http://hubblesite.org/newscenter/archive/releases/2016/04) say, but it won’t reach our galaxy for about 30 million years. The huge haze, known as the Smith Cloud, is barreling toward the galaxy at a speed of over 702,1oo mph. When the cloud, which astronomers say is 11,000 light years long and 2,500 light years across, reaches the galaxy it is has enough gas to create a burst of 2 million suns. The Smith Cloud is a well-known formation, discovered by doctoral student Gail Smith in the 1960s. It is unique because scientists have the ability to map its trajectory. The cloud can’t be seen in visible light, but if it could scientists say it would appear to be 30 times the size of the full moon. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/4199809/hydrogen-cloud-milky-way/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/4199809/hydrogen-cloud-milky-way/"},"headline":"A Giant Hydrogen Cloud Is Heading Toward the Milky Way","datePublished":"2016-01-29T16:15:56.000Z","dateModified":"2026-02-22T14:34:30.775Z","description":"The vast, invisible cloud is expected to reach the Milky Way in 30 million years","url":"https://time.com/4199809/hydrogen-cloud-milky-way/","keywords":["Space","astronomy","galaxy","stars"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/bltc3d2cb515d98041c/69887b45524fc03903df6841/smith-cloud1.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Maya Rhodan","jobTitle":null,"url":"https://time.com/author/maya-rhodan/"}],"articleSection":"Science","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/bltc3d2cb515d98041c/69887b45524fc03903df6841/smith-cloud1.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"smith-cloud","caption":"This composite image shows the size and location of the Smith Cloud on the sky.","creditText":"Z. Levay—NASA/ESA","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/science/","name":"Science"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/space/","name":"Space"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/4199809/hydrogen-cloud-milky-way/","name":"A Giant Hydrogen Cloud Is Heading Toward the Milky Way"}}]}] ```