comets

[sneezer1]

would a comet as big as pluto destroy it if it crashed into it?

 

[igorsboss]

Yes.<br /><br />What is "it"?

 

[newtonian]

sneezer1 - Can I asume we are it?<br /><br />In that case, that is nothing to sneeze at!<br /><br />Ceres, the largest asteroid (to my knowledge) is about 1,000 km in diameter.<br /><br />Charon, Pluto's moon, is about 800 km in diameter.<br /><br />Pluto is much larger, about 2,500 km in diameter.<br /><br />That would be real trouble for us - some would say it would destroy all civilization on earth!<br /><br />Thank God we have Jupiter, which attracts like a vacuum most comets that would otherwise be a danger to us- e.g. comet Shoemaker-Levi.

 

[rodrunner79]

<blockquote><font class="small">In reply to:</font><hr /><p><font color="yellow">Newtonian said:</font>eres, the largest asteroid (to my knowledge) is about 1,000 km in diameter. <p><hr /></p></p></blockquote><br /><br />I've read somewhere that Ceres is about 800 miles long (that's almost 1300 km). Is there any realible source(s) that tells me the real exact figures. I'm not directly attacking your statement, I'm also confused with the estimate on how old the universe is and how big. Some source say it's 12 BYO (billion years old) , some say it's 14, or 15 and as far as the size of the Universe. Some say 30 billion light years in diameter, 45 billion light years and some even say up to 150 billion light years. That's what confuse me.

 

[newtonian]

rodrunner - Is Ceres round? I'll look it up, btw. [Edit: Ceres is the largest asteroid; larger asteroids tend to be spherical]<br /><br />The age of universe is an educated guess. The diameter can be larger than the age [e.g. age: 12 billion years; radius (half the diameter) 14 billion light years] if the universe at some time expanded faster than light, as in various inflation theory models.<br /><br />And that is just one of many models.<br /><br />Don't forget acceleration of expansion rate, btw!

 

[newtonian]

From:<br /><br />http://www.solarviews.com/eng/ceres.htm<br /><br />A variant estimate:<br /><br />For two centuries it was the largest known rock in the solar system. The Texas-sized asteroid Ceres, about 930 kilometers (580 miles) across, was the first asteroid ever detected. <br /><br />And a new contender for largest:<br /><br />Recently, Ceres lost its claim to the title of biggest rock in the solar system. In July 2001, a larger object was found in the vast Kuiper belt of asteroids, stretching from 30 to 100 AU (2.8 to 9.3 billion miles away from the Sun.) This brightest and therefore biggest non-planet space rock, 2001 KX76, could be anywhere from 960 to 1270 kilometers (600 to 790 miles) across. <br /><br />I don't know now the largest comet known, btw. That would extend even further out into the Oort cloud.<br /><br />Most comets are thought to have an icy core diameter<br />Of just a few miles, but tails can be millions of miles long!<br /><br />I do know one scientist (Matese - LSU) put forth evidence for another planet near the Oort cloud.

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>rodrunner - Is Ceres round?<p><hr /></p></p></blockquote><br /><br />Yes, Ceres is approximately spherical. (It is somewhat lumpy, but still very round.) It is also suspected to be differentiated. What is really needed are good measurements of its mass, such as by sending a spacecraft to it and observing how the spacecraft's trajectory is affected. 1 Ceres has the distinction of being the first asteroid ever to be discovered (thus it has the number 1). Giuseppe Piazzi discovered it on the auspicious date of January 1, 1801, initially believing it to be a comet. But once its orbit had been computed, he realized it was something completely different. It was considered a full planet (albeit a small one) for some time, and the term "asteroid" was coined to indicate objects orbiting the Sun that looked like stars (points of light, not disks) when seen through a telescope. There was considerable debate about its status, but ultimately it lost out -- only things that showed a disk were to be called planets. (Tombaugh had his work cut out for him proving that Pluto had a disk, but he did manage it.)<br /><br />1 Ceres is over 900 km in diameter (I found figures of 933 and 948 due to uncertainty in the size estimates) and by itself represents a quarter of the mass in the entire asteroid belt. Hubble has imaged Ceres with resolutely barely sufficient to make out an albedo feature believed to be a very deep impact basin exposing the mantle of Ceres. Appropriately, this feature is named Piazzi. These observations confirmed that Ceres is definitely spherical.<br /><br />1 Ceres is long overdue for a spacecraft visit. NASA will fix that with the Dawn mission. Dawn is being built by Orbital Sciences and is planned to launch next summer. It will encounter Vesta (another big asteroid, but one smaller and less spherical than Ceres; it's the second-largest of the main-belt as <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[nexium]

I don't think we have found any comets with even 1% of the mass of Pluto. If we find one, we will consider calling it a planet instead of a comet. That much mass in a collision with a terrestrial planet would distroy all life unless it was a glancing blow which might leave both bodies mostly intact. If the density of the comet was only 1% that of Earth, it would be scattered widely, but a Pluto mass likely has to have a density of at least 5% of that of Earth as it's gravity would compact the core. Neil