{"id":21,"date":"2025-08-12T21:53:58","date_gmt":"2025-08-12T21:53:58","guid":{"rendered":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/?p=21"},"modified":"2025-08-15T16:37:18","modified_gmt":"2025-08-15T16:37:18","slug":"closer-to-planet-nine","status":"publish","type":"post","link":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/closer-to-planet-nine\/","title":{"rendered":"Closer to Planet Nine?"},"content":{"rendered":"\n

Eritas Yang \u201924 has made a far-out discovery. After two colleagues spotted a new dwarf planet in our solar system, a key moment came when they asked Yang to contribute her physical intuition and numerical skills to their deep space investigation. <\/p>\n\n\n\n

Yang majored in physics and was in the first year of her astrophysics PhD program at Princeton. Soon she noticed something strange about the dwarf\u2019s orbit, a finding that could shake up scientists\u2019 understanding of our planetary system. <\/p>\n\n\n\n

The temporary name of the celestial body is 2017 OF201, and it joins the group of extreme trans-Neptunian objects (eTNOs) due to its extremely wide orbit. Astronomers created the category of dwarf planets in 2006 for objects larger than asteroids that are too small to sweep their orbits clear of other bodies. With its estimated 435-mile diameter 2017 OF201 is substantially larger than other eTNOs and might be qualified as a dwarf planet, the same category as Pluto. <\/p>\n\n\n\n

\u201cFrom our observations, we realized that the orbit of 2017 OF201 is an outlier to the observed clustering of other TNOs, which has been interpreted as indirect evidence for the existence of a hypothetical Planet Nine,\u201d says Yang. \u201cOnce we realized that, we got excited, because that meant we could bring new insights to the Planet Nine problem.\u201d <\/p>\n\n\n\n

\"Illustration<\/figure>\n\n\n\n

Astronomers have speculated that this yet-to-be found far away ninth planet exists because orbits of other TNOs are in similar orientations they seem to be influenced by the gravity of an unknown larger object. But 2017 OF201\u2019s orbit deviates from their pattern. Whether or not this serves as a counterargument to the Planet Nine hypothesis depends on the stability of this object. Yang is currently analyzing the long-term stability of its orbit with and without the presence of Planet Nine through numerical simulations. <\/p>\n\n\n\n

When asked if she believes another planet lurks in the outer darkness, Yang says, \u201cI\u2019m neutral on this. I\u2019m simply excited to see that this discovery has led to more studies and discussions of Planet Nine.\u201d <\/p>\n\n\n\n

Like other eTNOs, 2017 OF201 is fantastically remote. At its greatest distance, its elliptical orbit careens 157 billion miles from the Sun. Much of the difficulty in finding eTNO\u2019s is that they spend almost all their time so far away they can\u2019t be detected. Yang\u2019s team got lucky spotting it because it was close enough to the Sun (8.3 billion miles) at the time of the discovery. Interestingly, it made its nearest approach of 4.1 billion miles in 1930, which coincidentally is when Pluto was discovered. The last time 2017 OF201 sped so near Earth was 24,256 years ago when hunter-gatherers are believed to have first reached North America. The fact that Yang\u2019s team observed this one object opens the possibility that hundreds of other eTNOs remain unfound in the outer solar system; they are just too far away to be detectable. <\/p>\n\n\n\n

Yang credits her knowledge of planetary dynamics to Harvey Mudd Assistant Professor of Physics Dan Tamayo. They wrote a paper on an analytical model for the long-term orbital dynamics of planetary systems. Thanks to her insights, Yang won the American Physical Society\u2019s 2024 LeRoy Apker Award, the most prestigious honor that group bestows on an undergraduate. <\/p>\n\n\n\n

\u201cEritas is a tenacious problem solver and thinker who won\u2019t let go of a problem until she figures it out, and she\u2019s also soft spoken and humble,\u201d says Tamayo. \u201cShe blew all my expectations out the window and did an incredible job. It\u2019s mind blowing that in her first year of grad school she\u2019s involved in detecting something like this.\u201d <\/p>\n\n\n\n

\u201cAmazing\u201d is how Yang describes her experience with Tamayo. \u201cHe gave me lots of confidence in my ability to do future research.\u201d <\/p>\n\n\n\n

She says her path toward astrophysics was \u201csuper-random\u201d and began with an interest in quantum mechanics while she was a high school student in Shanghai. \u201cI felt it would be a real pity if I lived my whole life without knowing how the world functions in a scientific way,\u201d she recalls. <\/p>\n\n\n\n

At HMC, she loved to hike Mount Baldy, especially at night. She liked to persuade people to join her at 2 a.m. so they could see the sun rise from the summit. On one occasion she witnessed a meteor shower from the peak. <\/p>\n\n\n\n

\u201cIt\u2019s fun to hike in the dark,\u201d she says. \u201cYou can feel yourself breathing. You feel the existence of yourself.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

Eritas Yang \u201924 has made a far-out discovery. After two colleagues spotted a new dwarf planet in our solar system, a key moment came when they asked Yang to contribute her physical intuition and numerical skills to their deep space investigation. Yang majored in physics and was in the first year of her astrophysics PhD […]<\/p>\n","protected":false},"author":1,"featured_media":26,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-21","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"acf":[],"_links":{"self":[{"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/posts\/21","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/comments?post=21"}],"version-history":[{"count":5,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/posts\/21\/revisions"}],"predecessor-version":[{"id":203,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/posts\/21\/revisions\/203"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/media\/26"}],"wp:attachment":[{"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/media?parent=21"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/categories?post=21"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-summer-2025\/wp-json\/wp\/v2\/tags?post=21"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}