New research by scientists from NASA and Japan\u2019s Osaka University suggests that rogue planets \u2013 worlds that drift through space untethered to a star \u2013 far outnumber planets that orbit stars. The results imply that NASA\u2019s Nancy Grace Roman Space Telescope, set to launch by May 2027, could find a staggering 400 Earth-mass rogue worlds. Indeed, this new study has already identified one such candidate.<\/p>\n\n\n\n
\u201cWe estimate that our galaxy is home to 20 times more rogue planets than stars \u2013 trillions of worlds wandering alone,\u201d said David Bennett, a senior research scientist at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland, and a co-author of two papers describing the results. \u201cThis is the first measurement of the number of rogue planets in the galaxy that is sensitive to planets less massive than Earth.\u201d<\/p>\n\n\n\n
The team\u2019s findings stem from a nine-year survey called MOA (Microlensing Observations in Astrophysics), conducted at the Mount John University Observatory in New Zealand. Microlensing events occur when an object such as a star or planet comes into near-perfect alignment with an unrelated background star from our vantage point. Because anything with mass warps the fabric of space-time, light from the distant star bends around the nearer object as it passes close by. The nearer object acts as a natural lens, creating a brief spike in the brightness of the background star\u2019s light that gives astronomers clues about the intervening object that they can\u2019t get any other way.<\/p>\n\n\n\n
\u201cMicrolensing is the only way we can find objects like low-mass free-floating planets and even primordial black holes,\u201d said Takahiro Sumi, a professor at Osaka University, and lead author of the paper with a new estimate of our galaxy\u2019s rogue planets. \u201cIt\u2019s very exciting to use gravity to discover objects we could never hope to see directly.\u201d<\/p>\n\n\n\n
The roughly Earth-mass rogue planet the team found marks the second discovery of its kind. The paper describing the finding will appear in a future issue of The Astronomical Journal. A second paper, which presents a demographic analysis that concludes that rogue planets are six times more abundant than worlds that orbit stars in our galaxy, will be published in the same journal.<\/p>\n\n\n\n
Pint-Sized Planets<\/strong> \u201cWe found that Earth-size rogues are more common than more massive ones,\u201d Sumi said. \u201cThe difference in star-bound and free-floating planets\u2019 average masses holds a key to understanding planetary formation mechanisms.\u201d<\/p>\n\n\n\n World-building can be chaotic, with all of the forming celestial bodies gravitationally interacting as they settle into their orbits. Planetary lightweights aren\u2019t tethered as strongly to their star, so some of these interactions end up flinging such worlds off into space. So begins a solitary existence, hidden amongst the shadows between stars.<\/p>\n\n\n\n In one of the early episodes of the original Star Trek series, the crew encounters one such lone planet amid a so-called star desert. They were surprised to ultimately find Gothos, the starless planet, habitable. While such a world may be plausible, the team emphasizes that the newly detected \u201crogue Earth\u201d probably doesn\u2019t share many other characteristics with Earth beyond a similar mass.<\/p>\n\n\n\n Roman\u2019s Hunt for Hidden Worlds<\/strong> \u201cRoman will be sensitive to even lower-mass rogue planets since it will observe from space,\u201d said Naoki Koshimoto, who led the paper announcing the detection of a candidate terrestrial-mass rogue world. Now an assistant professor at Osaka University, he conducted this research at Goddard. \u201cThe combination of Roman\u2019s wide view and sharp vision will allow us to study the objects it finds in more detail than we can do using only ground-based telescopes, which is a thrilling prospect.\u201d<\/p>\n\n\n\n Previous best estimates, based on planets found orbiting stars, suggested Roman would spot 50 terrestrial-mass rogue worlds. These new results suggest it could actually find about 400, though we\u2019ll have to wait until Roman begins scanning the skies to make more certain predictions. Scientists will couple Roman\u2019s future data with ground-based observations from facilities such as Japan’s PRIME (Prime-focus Infrared Microlensing Experiment) telescope, located at the South African Astronomical Observatory in Sutherland. This 1.8-meter telescope will build on MOA\u2019s work by conducting the first wide-area microlensing survey in near-infrared light. It\u2019s equipped with four detectors from Roman\u2019s detector development program, contributed by NASA as part of an international agreement with JAXA (Japan Aerospace Exploration Agency).<\/p>\n\n\n\n Each microlensing event is a one-time occurrence, meaning astronomers can\u2019t go back and repeat the observations once they\u2019re over. But they\u2019re not instantaneous.<\/p>\n\n\n\n \u201cA microlensing signal from a rogue planet can take from a few hours up to about a day, so astronomers will have a chance to do simultaneous observations with Roman and PRIME,\u201d Koshimoto said.<\/p>\n\n\n\n Seeing them from both Earth and Roman\u2019s location a million miles away will help scientists measure the masses of rogue planets much more accurately than ever before, deepening our understanding of the worlds that grace our galaxy.<\/p>\n\n\n\n The Nancy Grace Roman Space Telescope is managed at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory and Caltech\/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are Ball Aerospace and Technologies Corporation in Boulder, Colorado; L3Harris Technologies in Melbourne, Florida; and Teledyne Scientific & Imaging in Thousand Oaks, California.<\/p>\n","protected":false},"excerpt":{"rendered":" New research by scientists from NASA and Japan\u2019s Osaka University suggests that rogue planets…<\/p>\n","protected":false},"author":1,"featured_media":2120,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[102],"tags":[219,210,211,215],"class_list":["post-2106","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-space-news","tag-indian-space-magazines","tag-indian-space-news","tag-space-magazines","tag-space-news-online"],"_links":{"self":[{"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/posts\/2106","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/comments?post=2106"}],"version-history":[{"count":1,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/posts\/2106\/revisions"}],"predecessor-version":[{"id":2121,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/posts\/2106\/revisions\/2121"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/media\/2120"}],"wp:attachment":[{"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/media?parent=2106"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/categories?post=2106"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.spacepreneurmag.com\/index.php\/wp-json\/wp\/v2\/tags?post=2106"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
In only a few decades, we’ve gone from wondering whether the worlds in our solar system are alone in the cosmos to discovering more than 5,300 planets outside our solar system. The vast majority of these newfound worlds are either huge, extremely close to their host star, or both. By contrast, the team\u2019s results suggest that rogue planets tend to be on the petite side.<\/p>\n\n\n\n
Microlensing events that reveal solitary planets are extraordinarily rare, so one key to finding more is to cast a wider net. That\u2019s just what Roman will do when it launches by May 2027.<\/p>\n\n\n\n