{"id":38389,"date":"2024-12-22T13:45:00","date_gmt":"2024-12-22T13:45:00","guid":{"rendered":"https:\/\/www.lifeandnews.com\/articles\/?p=38389"},"modified":"2024-12-30T21:32:12","modified_gmt":"2024-12-30T21:32:12","slug":"2-populations-of-dark-comets-in-the-solar-system-could-tell-researchers-where-the-earth-got-its-oceans","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/2-populations-of-dark-comets-in-the-solar-system-could-tell-researchers-where-the-earth-got-its-oceans\/","title":{"rendered":"2 populations of dark comets in the solar system could tell researchers where the Earth got its oceans"},"content":{"rendered":"\n

Darryl Z. Seligman<\/a>, Michigan State University<\/a><\/em><\/p>\n\n\n\n

The water that makes up the oceans acted as a key ingredient for the development of life on Earth. However, scientists still do not know where the water here on Earth<\/a> came from in the first place.<\/p>\n\n\n\n

One leading idea is that space rocks such as comets and asteroids delivered water to the Earth through impacts. As a planetary scientist<\/a>, I\u2019m curious about the kinds of space objects that could have led to the formation of the oceans. For the past few years, I\u2019ve been studying a type of object that I called a dark comet \u2013 which could be just the culprit. In a new study<\/a> my colleagues and I published in December 2024, we discovered two classes of these elusive dark comets<\/p>\n\n\n\n

\"An
Dark comets fly through space, but unlike comets, they don\u2019t have dust tails. Adina Feinstein and NASA\u2019s Earth Observatory<\/figcaption><\/figure>\n\n\n\n

What is a comet?<\/h2>\n\n\n\n

The solar system is teaming with small bodies such as comets and asteroids. These space rocks were fundamental building blocks of planets in the early solar system, while the remaining leftovers are the comets and asteroids seen today.<\/p>\n\n\n\n

These objects are also avenues by which material can be transported throughout the solar system. These small worlds can contain things such as rubble, ice and organic material as they fly through space. That\u2019s why researchers see them as good potential candidates for delivering ices such as water and carbon dioxide to the Earth while it was forming.<\/p>\n\n\n\n

Traditionally, the difference between comets<\/a> and asteroids<\/a> is that comets have beautiful cometary tails<\/a>. These tails form because comets have ice in them, while asteroids supposedly do not.<\/p>\n\n\n\n

When a comet gets close to the Sun, these ices heat up and sublimate, which means they turn from ice into gas<\/a>. The gas heats up because of the sunlight and is then blown off the comet\u2019s surface in a process called outgassing. This outgassing brings with it rubble and small dust grains, which reflect sunlight.<\/p>\n\n\n\n

Asteroids<\/a>, on the other hand, do not have cometary tails. Presumably, they are more like classic rocks \u2013 without ice on their surfaces.<\/p>\n\n\n\n

What is a nongravitational acceleration?<\/h2>\n\n\n\n

The outgassing material from the surface of a comet produces a cometary tail and a rocketlike recoil. The fast moving gas pushes on the surface of the comet, and this causes it to accelerate<\/a>. This process drives comets\u2019 motion through space on top of the motion set by the gravitational pull of the Sun.<\/p>\n\n\n\n

So, when comets outgas, they have what planetary scientists call nongravitational acceleration \u2013 motion that isn\u2019t caused by the gravity of objects in the solar system. Planetary scientists typically measure the nongravitational accelerations of comets after detecting their cometary tails.<\/p>\n\n\n\n

What are dark comets?<\/h2>\n\n\n\n

Our team identified<\/a> a class of small bodies in the solar system that take some of the properties of both comets and asteroids. We called them dark comets.<\/p>\n\n\n\n

These dark comets have nongravitational accelerations like comets, so they experience a rocketlike recoil from comet outgassing. However, they don\u2019t have the dusty tails that most comets have.<\/p>\n\n\n\n

In other words, they look like typical asteroids, but gravity alone can\u2019t explain their motion.<\/p>\n\n\n\n

The first interstellar object, \u2019Oumuamua<\/a>, was the first comet or asteroid-size body that was detected in the solar system that came from outside of the solar system.<\/p>\n\n\n\n

\u2019Oumuamua displayed this same mysterious combination of no dust tail but a cometlike nongravitational acceleration<\/a>, which led to many theories trying to explain what the object could have been. One option is that it was outgassing like a comet but not producing a dusty tail<\/a>.<\/p>\n\n\n\n

Since \u2019Oumuamua was first spotted in 2017, my colleagues and I have identified other dark comets within the solar system. In our study<\/a>, we found seven new dark comets, bringing the total to 14.<\/p>\n\n\n\n

Now that we\u2019ve found more dark comets, we\u2019ve noticed that they come in two flavors. Outer dark comets are larger \u2013 about a mile wide in size \u2013 and on more elliptical orbits farther out in the solar system. Inner dark comets are smaller \u2013 typically 1,000 feet in size \u2013 and on circular orbits close to the Earth.<\/p>\n\n\n\n

\"A
Outer dark comets, shown in red, have longer orbits than inner dark comets, shown in gray. Darryl Seligman<\/figcaption><\/figure>\n\n\n\n

Contributions to the Earth\u2019s oceans?<\/h2>\n\n\n\n

It\u2019s still not clear exactly what these dark comets are. They may not even be traditional comets if they don\u2019t have icy surfaces.<\/p>\n\n\n\n

However, the most likely answer for their nongravitational accelerations is that they outgas water, like a comet, but don\u2019t produce a dusty tail \u2013 at least not one we can see when we look at them with our telescopes.<\/p>\n\n\n\n

If this is the case, there are sure to be many more<\/a> of these objects, parading around like asteroids, still yet to be identified.<\/p>\n\n\n\n

Since scientists don\u2019t know for sure where the Earth\u2019s water came from, if there really are lots of dark comets that have water near Earth, it is possible that these dark comets contributed water to the early Earth.<\/p>\n\n\n\n

These dark comets could tell researchers more about the origins of Earth\u2019s oceans and the development of life here on Earth.<\/p>\n\n\n\n

Reasons to be excited for the future<\/h2>\n\n\n\n

This research is really just the tip of the iceberg, because we only just started finding these dark comets in 2023.<\/p>\n\n\n\n

The Vera C. Rubin Observatory\u2019s Legacy Survey of Space and Time<\/a>, which comes online in 2025, will start scanning the entire southern sky almost every night to spot anything that moves. This telescope, located on a mountain in Chile\u2019s Atacama desert, is home to the largest camera ever built.<\/p>\n\n\n\n

It will give astronomers almost five orders of magnitude greater sensitivity for detecting moving objects in the night sky. It will likely help my colleagues and me discover lots of new dark comets in the near future.<\/p>\n\n\n\n

Telescopes that are already operating, such as the Hubble Space Telescope<\/a> and the James Webb Space Telescope<\/a>, could also help my team watch for outgassing or ice on the surface of the 14 dark comets we\u2019ve already identified. https:\/\/www.youtube.com\/embed\/agnSwV451_4?wmode=transparent&start=0 Landing on a dark comet would probably look similar to Hayabusa2\u2019s rendezvous with the Ryugu asteroid.<\/p>\n\n\n\n

Finally, the JAXA Hayabusa2<\/a> extended mission is slated to rendezvous with one of the inner dark comets, 1998 KY26<\/a>, in 2031. Therefore, we will be able to see the surface of a dark comet in exquisite detail.<\/p>\n\n\n\n

Darryl Z. Seligman<\/a>, Postdoctoral Fellow in Physics and Astronomy, Michigan State University<\/a><\/em><\/p>\n\n\n\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Darryl Z. Seligman, Michigan State University The water that makes up the oceans acted as a key ingredient for the development of life on Earth. However, scientists still do not know where the water here on Earth came from in the first place. One leading idea is that space rocks such as comets and asteroids […]<\/p>\n","protected":false},"author":56,"featured_media":38390,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[292,1862,118,3410],"tags":[15871,4665,885,891,886,860,2800,169],"_links":{"self":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/38389"}],"collection":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/users\/56"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/comments?post=38389"}],"version-history":[{"count":1,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/38389\/revisions"}],"predecessor-version":[{"id":38391,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/38389\/revisions\/38391"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media\/38390"}],"wp:attachment":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media?parent=38389"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/categories?post=38389"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/tags?post=38389"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}