{"id":998,"date":"2023-04-25T18:15:25","date_gmt":"2023-04-25T18:15:25","guid":{"rendered":"https:\/\/www.dereumlabs.com\/global\/?p=998"},"modified":"2023-04-25T18:15:27","modified_gmt":"2023-04-25T18:15:27","slug":"asteroids-comet-like-tail-is-not-made-of-dust-solar-observatories-reveal","status":"publish","type":"post","link":"http:\/\/www.dereumlabs.com\/global\/news\/asteroids-comet-like-tail-is-not-made-of-dust-solar-observatories-reveal\/","title":{"rendered":"Asteroid\u2019s Comet-Like Tail Is Not Made of Dust, Solar Observatories Reveal"},"content":{"rendered":"\n

We have known for a while that asteroid 3200 Phaethon<\/a> acts like a comet. It brightens and forms a tail when it\u2019s near the Sun, and it is the source of the annual Geminid meteor shower, even though comets are responsible for most meteor showers. Scientists had blamed Phaethon\u2019s comet-like behavior on dust escaping from the asteroid as it\u2019s scorched by the Sun. However, a new study using two NASA solar observatories reveals that Phaethon\u2019s tail is not dusty at all but is actually made of sodium gas.<\/p>\n\n\n\n

\u201cOur analysis shows that Phaethon\u2019s comet-like activity cannot be explained by any kind of dust,\u201d said California Institute of Technology PhD student Qicheng Zhang, who is the lead author of a paper published in\u00a0the\u00a0Planetary Science Journal<\/a>\u00a0reporting the results.<\/p>\n\n\n\n

\"Artist's<\/figure>\n\n\n\n

Asteroids<\/a>, which are mostly rocky, do not usually form tails when they approach the Sun. Comets<\/a>, however, are a mix of ice and rock, and typically do form tails as the Sun vaporizes their ice, blasting material off their surfaces and leaving a trail along their orbits. When Earth passes through a debris trail, those cometary bits burn up in our atmosphere and produce a swarm of shooting stars \u2013 a meteor shower.<\/p>\n\n\n\n

After astronomers discovered Phaethon in 1983, they realized that the asteroid\u2019s orbit matched that of the Geminid meteors. This pointed to Phaethon as the source of the annual meteor shower, even though Phaethon was an asteroid and not a comet.<\/p>\n\n\n\n

\"An<\/a>
This two-hour sequence of images from the Solar and Heliospheric Observatory (SOHO) shows Phaethon (circled) moving relative to background stars. The images were taken on May 15, 2022, when the 3.4-mile-wide asteroid ventured close to the Sun, at a distance of 13 million miles. While SOHO routinely observes the Sun, it also observes many objects that pass near the Sun, including comets and asteroids. The random white specks are energetic particles, or cosmic rays, that constantly bombard the SOHO camera.<\/figcaption><\/figure><\/div>\n\n\n\n

<\/p>\n\n\n\n

In 2009, NASA\u2019s Solar Terrestrial Relations Observatory<\/a> (STEREO) spotted a short tail extending from Phaethon as the asteroid reached its closest point to the Sun (or \u201cperihelion\u201d) along its 524-day orbit. Regular telescopes hadn\u2019t seen the tail before because it only forms when Phaethon is too close to the Sun to observe, except with solar observatories. STEREO also saw Phaethon\u2019s tail develop on later solar approaches in 2012 and 2016. The tail\u2019s appearance supported the idea that dust was escaping the asteroid\u2019s surface when heated by the Sun.<\/p>\n\n\n\n

However, in 2018, another solar mission imaged part of the Geminid debris trail and found a surprise. Observations from NASA\u2019s Parker Solar Probe showed that the trail contained far more material than Phaethon could possibly shed during its close approaches to the Sun.<\/p>\n\n\n\n

Zhang\u2019s team wondered whether something else, other than dust, was behind Phaethon\u2019s comet-like behavior. \u201cComets often glow brilliantly by sodium emission when very near the Sun, so we suspected sodium could likewise serve a key role in Phaethon\u2019s brightening,\u201d Zhang said.<\/p>\n\n\n\n

An earlier study, based on models and lab tests, suggested that the Sun\u2019s intense heat during Phaethon\u2019s close solar approaches could indeed vaporize sodium within the asteroid and drive comet-like activity.<\/p>\n\n\n\n

Hoping to find out what the tail is really made of, Zhang looked for it again during Phaethon\u2019s latest perihelion in 2022. He used the\u00a0Solar and Heliospheric Observatory\u00a0(SOHO) spacecraft \u2014 a joint mission between NASA and the European Space Agency (ESA) \u2013 which has color filters that can detect sodium and dust. Zhang\u2019s team also searched archival images from STEREO and SOHO, finding the tail during 18 of Phaethon\u2019s close solar approaches between 1997 and 2022.<\/p>\n\n\n\n

In SOHO\u2019s observations, the asteroid\u2019s tail appeared bright in the filter that detects sodium, but it did not appear in the filter that detects dust. In addition, the shape of the tail and the way it brightened as Phaethon passed the Sun matched exactly what scientists would expect if it were made of sodium, but not if it were made of dust.<\/p>\n\n\n\n

This evidence indicates that Phaethon\u2019s tail is made of sodium, not dust.<\/p>\n\n\n\n

\u201cNot only do we have a really cool result that kind of upends 14 years of thinking about a well-scrutinized object,\u201d said team member Karl Battams of the Naval Research Laboratory, \u201cbut we also did this using data from two heliophysics spacecraft \u2013 SOHO and STEREO \u2013 that were not at all intended to study phenomena like this.\u201d<\/p>\n\n\n\n

\"Two<\/figure>\n\n\n\n

Zhang and his colleagues now wonder whether some\u00a0comets discovered by SOHO\u00a0\u2013 and by citizen scientists studying SOHO images as part of the\u00a0Sungrazer Project\u00a0\u2013 are not comets at all.<\/p>\n\n\n\n

\u201cA lot of those other sunskirting \u2018comets\u2019 may also not be \u2018comets\u2019 in the usual, icy body sense, but may instead be rocky asteroids like Phaethon heated up by the Sun,\u201d Zhang explained.<\/p>\n\n\n\n

Still, one important question remains: If Phaethon doesn\u2019t shed much dust, how does the asteroid supply the material for the Geminid meteor shower we see each December?<\/p>\n\n\n\n

Zhang\u2019s team suspects that some sort of disruptive event a few thousand years ago \u2013 perhaps a piece of the asteroid breaking apart under the stresses of Phaethon\u2019s rotation \u2013 caused Phaethon to eject the billion tons of material estimated to make up the Geminid debris stream. But what that event was remains a mystery.<\/p>\n\n\n\n

More answers may come from an upcoming Japan Aerospace Exploration Agency (JAXA) mission called DESTINY+ (short for Demonstration and Experiment of Space Technology for Interplanetary voyage Phaethon fLyby and dUst Science). Later this decade, the DESTINY+ spacecraft is expected to fly past Phaethon, imaging its rocky surface and studying any dust that might exist around this enigmatic asteroid.<\/p>\n\n\n\n

We recommend you: Starship explodes minutes after taking flight<\/a><\/p>\n\n\n\n

Source: NASA<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

We have known for a while that asteroid 3200 Phaethon acts like a comet. It brightens and forms a tail when it\u2019s near the Sun, and it is the source of the annual Geminid meteor shower, even though comets are responsible for most meteor showers. Scientists had blamed Phaethon\u2019s comet-like behavior on dust escaping from the asteroid […]<\/p>\n","protected":false},"author":1,"featured_media":999,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false},"categories":[3],"tags":[321,320,322,323],"aioseo_notices":[],"_links":{"self":[{"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/posts\/998"}],"collection":[{"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/comments?post=998"}],"version-history":[{"count":1,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/posts\/998\/revisions"}],"predecessor-version":[{"id":1000,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/posts\/998\/revisions\/1000"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/media\/999"}],"wp:attachment":[{"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/media?parent=998"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/categories?post=998"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.dereumlabs.com\/global\/wp-json\/wp\/v2\/tags?post=998"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}