How big of an object would have created Tycho on the Moon?

[willpittenger]

Rough diameter would suffice. Also, any opinions on whether it was a comet or asteroid? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[thalion]

I read once that a (rough) rule of thumb is that a crater is often about 10 times larger than the impactor that created it. Given that Tycho's diameter is 85 km, that means its impactor was probably about 8.5 km in diameter. In fact, plugging a 8.5-km, rocky impactor on the following site, with an velocity of 7 km/s (which I think is reasonable for a NEO) gives a crater diameter of 77 km, which is fairly close.<br /><br />http://janus.astro.umd.edu/astro/impact/<br /><br />Unfortunately, nobody knows for sure if it was a comet or asteroid, but I'm guessing the odds favor it being an asteroid.

 

[willpittenger]

<blockquote><font class="small">In reply to:</font><hr /><p>They need to get to the site, do some basic geological processing of the impactites there and find out<p><hr /></p></p></blockquote><br />With rovers or people? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>