国产三级大片在线观看-国产三级电影-国产三级电影经典在线看-国产三级电影久久久-国产三级电影免费-国产三级电影免费观看

Set as Homepage - Add to Favorites

【??? ??? ??】Enter to watch online.What are comets? The secret lives of space snowballs.

Source: Editor:fashion Time:2025-07-05 13:52:24

No one yet knows how our planet evolved into an inhabited world,??? ??? ?? with the chemistry to spawn a variety of lifeforms. But scientists believe comets hurtling through space may hold that wisdom.

Like an asteroid, a comet orbits the sun. The latter is a ball of ice, dust, and rock that formed in the outer solar system. These icy bodies are left over from the early days of planet formation, about 4.6 billion years ago. Their ice starts to disintegrate as they get closer and closer to the sun, converting from a solid to a gas in one swift process, skipping over the liquid phase.

Laypeople sometimes confuse shooting stars, aka meteors, for comets because they each create a glowing streak that humans can see. But comets are known for their telltale tails, millions-of-miles-long debris trails of vaporizing ice, dust, and carbon dioxide.


You May Also Like

In a NASA video, Ryan Park, a near-Earth asteroid expert, sums up the differences in space rocks: "Asteroids are rocky, comets are icy, and meteors are much smaller and are the shooting stars that you see up in the sky."

SEE ALSO: NASA's Hubble confirms largest comet ever seen

Hundreds of years ago, comets were considered bad omens. Legend holds that Pope Callixtus III excommunicated Halley's Comet in 1456 as an "instrument of the devil," though a Catholic priest disputed that as myth in a 1908 article published in Popular Astronomy.

Scientists today know these icy objects as ancient relics of the solar system. Astronomers often think of them as time capsules.

"Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system," according to NASA.

How many comets are in the solar system?

As 2023 came to a close, there were more than 3,900 known comets. Astronomers say countless others are likely orbiting the sun beyond Neptune in a disk known as the Kuiper Belt or on the outer edge of the solar system, in the so-called Oort Cloud, about 50 times farther from the sun. The Oort Cloud is thought to be a sphere of ancient, icy objects surrounding the system. NASA says the cloud remains a theory because the comets there have been too faint and distant to be directly observed.

Comets are sometimes dislodged from their home in the outer solar system by the gravity of another object, redirecting them toward the sun. As the comet gains speed, it swings around the sun. If it survives this close encounter, it heads back toward home.

Mashable Light Speed Want more out-of-this world tech, space and science stories? Sign up for Mashable's weekly Light Speed newsletter. By clicking Sign Me Up, you confirm you are 16+ and agree to our Terms of Use and Privacy Policy. Thanks for signing up!

Depending on where a comet originated, it could take hundreds to millions of years to complete a single orbit. Comet Bernardinelli-Bernstein, for example, follows a 3-million-year-long oval-shaped orbit, taking it about half a light-year away from the sun.

Astronomers explaining the Kuiper BeltAstronomers say countless comets are likely orbiting the sun beyond Neptune in a disk known as the Kuiper Belt. Credit: NASA illustration

Want more scienceand tech news delivered straight to your inbox? Sign up for Mashable's Light Speed newslettertoday. 

What is the largest comet found so far?

Bernardinelli-Bernstein made news in 2022 when scientists confirmed it as the largest comet observed so far, spanning the length of three marathons end-to-end. A team of scientists used the Hubble Space Telescope, an Earth-orbiting observatory shared by NASA and the European Space Agency, to determine that its nucleus — the solid, frozen core — is about 85 miles wide.

That's about 50 times larger than the average known comet and 40 percent larger than the runner up. The previous record-holder for largest comet was C/2002 VQ94, with a nucleus estimated to be 60 miles across.

Comparing comet nucleus sizesHale-Bopp is no competition for Comet Bernardinelli-Bernstein. Credit: NASA / ESA / Zena Levy (STScI) illustration

Researchers say the scale of Bernardinelli-Bernstein, which has a mass of 500 trillion tons, is significant because it provides a clue about the size range of other comets orbiting in the distant outskirts of our solar system.

"This comet is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system," David Jewitt, a UCLA astronomer, said in a statement.


Related Stories
  • What's a shooting star? Relax. You're not the only one confused.
  • NASA's Hubble confirms largest comet ever seen
  • Vigilant amateur asteroid hunters keep watch for menacing space rocks
  • Look up before comet Nishimura vanishes in the sun's glare
  • The green comet will zip out of the sky soon. You can still see it.

Why do some comets appear green?

In January 2023, a comet dubbed C/2022 E3 (ZTF) captured the attention of people around the world because of its color, receiving the nickname "the green comet" for its emerald hue. The color comes from carbon in the gas cloud surrounding its nucleus, known as the coma.

The comet wasn’t nearly as spectacular as NEOWISE was back in 2020, the brightest comet to come this way since Hale-Bopp in the 1990s. But it was still a rare opportunity to see a space phenomenon that won't return for another 50 millenia or more.

"Asteroids are rocky, comets are icy, and meteors are much smaller and are the shooting stars that you see up in the sky."

In recent years, several spacecraft have studied comets up close. NASA’s Stardust mission brought back samples from Comet Wild-2 to Earth in 2006. The particles were chock full of hydrocarbons — chemicals considered the "building blocks" of life as we know it.

The European Space Agency's Rosetta mission, which included several onboard NASA instruments, dropped a lander on Comet 67P Churyumov-Gerasimenko's nucleus, then orbited it for two years. The European mission also detected building blocks of life.

Rosetta mission studying Comet 67P Churyumov-GerasimenkoThe European Space Agency's Rosetta mission studied Comet 67P Churyumov-Gerasimenko's nucleus. Credit: ESA / Rosetta

Astronomers are also using the James Webb Space Telescope, a partnership of NASA, ESA, and the Canadian Space Agency, to research comets in infrared wavelengths of light that are invisible to human eyes. The telescope is orbiting the sun about 1 million miles from Earth.

At those wavelengths, scientists will study the chemical composition of the dust and gas that comes off a comet's nucleus and discern what it is, said Heidi Hammel, a planetary scientist, in a NASA statement. They hope to get to the bottom of whether all solar system comets start out the same but evolve differently or if they are chemically distinct from the start.

"If this is primitive material, it will give us some clues to the makeup of the early solar system," she said.

Topics NASA

0.2567s , 9969.6796875 kb

Copyright © 2025 Powered by 【??? ??? ??】Enter to watch online.What are comets? The secret lives of space snowballs.,  

Sitemap

Top 主站蜘蛛池模板: av中文字幕一区二区三区久久 | 欧美日韩国产中文字幕在线 | 69堂午夜精品视频在线 | 老熟妻内射精品一区 | 麻豆综合网 | 亚洲AV蜜桃秘 无码一区二区 | 天美传媒新剧国产网站 | 国产三级精品三级在线观看专 | 3d动漫精品一区视频在线观看 | 成年男人深夜在线视频 | 1区2区3区国产av天堂 | 国产乱伦人妻一区二区三区四区 | 日韩精品在线免费观看 | 日产一卡二卡乱码免费 | 亚洲国产欧美在线人成 | 中文字幕一区精品 | 中文字幕一卡二卡三卡四卡免费 | 91制片厂果冻传媒公司麻豆 | 曰韩精品无码一区二区三区 | 久久久国产高清 | 六月丁香久久丫 | 成人羞羞网站入口免费 | 国内精品A片XXX久久久 | 麻豆最新国产剧情AV原创免费 | 永久免费观看美女视频 | 国产一区在线看 | 亚洲国产日韩在线 | 亚洲欧美另类一区二区精品 | 亚洲第一区欧美 | 国产毛片一级片试看 | 国精产品999国精产精华好用吗 | 日韩精品无码一区二区免费A片 | 精品综合久久久久久97超人该 | 巨爆乳中文字幕巨爆区巨爆乳无码 | 亚洲偷自拍国综合色帝国 | 四虎最新网站 | 少妇性BBB搡BBB爽爽爽小说 | 欧美三级片电影中文字 | 99久久精品免费看国产一区二区三 | 国产无码电影网热搜电影高清免费观看 | 国产精品亚洲а怡红院 |