4 ms·

This is all predicated on 25 km/s being very fast, which in this case it really isn't. Man made objects like the ISS travel at 7 km/s, so these are relatively a

This is all predicated on 25 km/s being very fast, which in this case it really isn't. Man made objects like the ISS travel at 7 km/s, so these are relatively achievable speeds, even for humanity. We can look at meteor impacts, too. The first source I found on the topic said meteors commonly impact with 11- 72 km/s. [1] This happens every day with small objects and we're fine. With bigger objects you'll get extinction events and features like the Chicxulub crater, but no way you'd see anything "penetrate Earth surface ... like any hollow bullet does, or ... cut Earth in half like a high power laser." The speed of light is 300,000 km/s, more than 10,000 times faster than Oumuamua. An object at 0.1c or even 0.01c would be very threatening, but those are still orders of magnitude faster than Oumuamua. In short - 25 km/s isn't that fast, don't worry about it. There are plenty of asteroids that could hit us faster than that that we also don't always see! [1] - https://www.amsmeteors.org/meteor-showers/meteor-faq/ https://www.amsmeteors.org/meteor-showers/meteor-faq/

saagarjha 8y ago
> This is all predicated on 25 km/s being very fast, which in this case it really isn't. Man made objects like the ISS travel at 7 km/s, so these are relatively achievable speeds, even for humanity. Quite a few spacecraft have reached this speed. Off the top of my head, I think Juno reached something like 70 km/s when approaching Jupiter.
- planteen 8y ago
  That's pretty meaningless though, the speed of interest is the heliocentric velocity. Juno was accelerating toward the largest planet in the solar system and orbiting it, not doing a gravitational slingshot. The current record is Voyager 1, which got its speed from a flyby tour of the outer solar system. It is going 17 km/s. https://en.wikipedia.org/wiki/List_of_artificial_objects_leaving_the_Solar_System https://en.wikipedia.org/wiki/List_of_artificial_objects_lea...
joering2 8y ago
We still don't know what Oumuamua is made off of. I think we can agree anyone would rather be hurt by a baseball flying 10km/hour, than being hurt by a knife that travels 1km/h.
- saagarjha 8y ago
  Your intuition of how impacts work falls apart at high speeds.
- dragonwriter 8y ago
  > We still don't know what Oumuamua is made off of. The fact that it is tumbling and not coming on like a dart along it's long axis means it pretty much doesn't matter what it's made of, aside from it's total mass, it's not going to do some kind of radical penetration or anything else that unusual of it were to hit the Earth. (Even if it was a stabilized penetrator dart of some kind, AFAIK, that doesn't really change much about surface impact unless you make radically implausible assumptions of composition, but I think it might effect the probability of it making a ground impact rather than an airburst.)

saagarjha 8y ago

> This is all predicated on 25 km/s being very fast, which in this case it really isn't. Man made objects like the ISS travel at 7 km/s, so these are relatively achievable speeds, even for humanity. Quite a few spacecraft have reached this speed. Off the top of my head, I think Juno reached something like 70 km/s when approaching Jupiter.

planteen 8y ago
That's pretty meaningless though, the speed of interest is the heliocentric velocity. Juno was accelerating toward the largest planet in the solar system and orbiting it, not doing a gravitational slingshot. The current record is Voyager 1, which got its speed from a flyby tour of the outer solar system. It is going 17 km/s. https://en.wikipedia.org/wiki/List_of_artificial_objects_leaving_the_Solar_System https://en.wikipedia.org/wiki/List_of_artificial_objects_lea...

joering2 8y ago

We still don't know what Oumuamua is made off of. I think we can agree anyone would rather be hurt by a baseball flying 10km/hour, than being hurt by a knife that travels 1km/h.

saagarjha 8y ago
Your intuition of how impacts work falls apart at high speeds.
dragonwriter 8y ago
> We still don't know what Oumuamua is made off of. The fact that it is tumbling and not coming on like a dart along it's long axis means it pretty much doesn't matter what it's made of, aside from it's total mass, it's not going to do some kind of radical penetration or anything else that unusual of it were to hit the Earth. (Even if it was a stabilized penetrator dart of some kind, AFAIK, that doesn't really change much about surface impact unless you make radically implausible assumptions of composition, but I think it might effect the probability of it making a ground impact rather than an airburst.)