21–30 of 66 posts
It's remarkable to me that someone peering up at the moon right when this struck could have noticed the flash.
[deleted]
Earlier quoted context omitted.
But without an atmosphere the shockwave from that 100 kiloton explosion should be pretty minimal (through the ground only), and any debris flung into the atmosphere would fall right back down on parabolic trajectories (or go into orbit), not linger in the sky for months/years. The danger posed by such an explosion, off the top of my head, would be getting hit by the object itself, getting hit by falling debris ejecte…
Of course without an atmosphere everyone would be dead anyway, so I suppose this is kind of a silly thing to think about. Just never walk out of your front-door without wearing your space suit.
I found the footnote particularly interesting: "The Moon has no oxygen atmosphere, so how can something explode? Lunar meteors don't require oxygen or combustion to make themselves visible. They hit the ground with so much kinetic energy that even a pebble can make a crater several feet wide. The flash of light comes not from combustion but rather from the thermal glow of molten rock and hot vapors at the impact site…
On the other hand, if something creates a bunch of gas in space, there's really no medium for a shock wave, other than the gas created. So it's not going to be as damaging. Though, there's no reason a sub-lunar explosion would be much different that what we get on the earth.
And that ladies and gentlemen is why having an atmosphere is a very good thing.
I wonder if the meteorite that exploded in the atmosphere over Russia did more or less damage than if it had struck the earth intact. Clearly Atmosphere makes a good shield for burning up the small meteorites - but I wonder if it exacerbates the damage from medium sized ones?
>Impact Velocity - This is the velocity of the projectile before it enters the atmosphere. The minimum impact velocity on Earth is 11 km/s. Typical impact velocities are 17 km/s for asteroids and 51 km/s for comets. The maximum Earth impact velocity for objects orbiting the sun is 72 km/s
For comparison, the velocity of the ISS is about 7.7 km/s, about equal to the speed of detonating cord.
Just wanted to say that I helped build this site. It's 2009/2010-era Django site built on feincms with a PostgreSQL backend. Originally it was a Plone site but after a year we realized it was too hard to meet the deadlines of NASA VIPs. So we moved it to Django. Also, myself and the other developers have NEVER been happy with the flash on the front page. :P
oh gawd, transformers has started...
And that ladies and gentlemen is why having an atmosphere is a very good thing.
Earlier quoted context omitted.
[deleted]
The article says yes, but then quantifies it at 4th magnitude which really isn't that bright. Generally in my area you can't see anything 4th magnitude, nearly ever, due to light pollution. The thought of that right next to even a crescent moon sounds pretty hard to see even in dark skies.