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Hiroshima exploded 67 terajoules of energy i.e. $6.7\times 10^{13}$ joules. We may calculate the mass of the Russian meteor assuming that the speed is $v=20,000$ m/s: $$ \frac{1}{2} mv^2 = 6.7 \times 10^{13} $$ We obtain 335 tons. The numbers aren't precise but they're in the ballpark and reasonable. The Russian academy of sciences actually estimates 10,000 ...


10

Remember that meteoroids are celestial objects. At these scales, it is quite common for relative velocities to be extremely large. When such a fast-moving object enters the atmosphere of the Earth, the air slows it down due to its viscosity. However, the meteor is moving very, very fast. Unlike most falling objects, it doesn't get a chance to even reach ...


10

The Perseids in August are always good with 30+ meteors per hour. If you can get to a dark sky, you won't be disappointed. The Leonids hit their thirty-three year peak just a couple years ago so it will be a while before they peak again. The Perseids peaked in the mid-1990s (I saw 200 meteors in 1.5 hours through a hole in the clouds that just showed ...


10

At the risk of being snarky (each definition is from wikipedia)... Comet - A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. ...


8

Meteoroids come in a very large range of sizes, from specks of dust to many-kilometer-wide boulders. Explosions like that of the Chelyabinsk meteor are only found meteors that are larger than a few meters in size but smaller than a kilometer. Though the details are argued endlessly by those who study such phenomena (it is very hard to get good data when you ...


7

Airburst, I think, it is called. An article on wired.com covers exactly this question the rock was already going very fast when it entered the Earth’s atmosphere. There is no way the air could get it down to terminal velocity – there just wasn’t enough distance for a rock this large. But this air resistance is essentially the reason that it ...


7

John's answer is a good one, I just wanted to add some equations and addition thought. Let me start here: Heating is really only significant when you get a shock wave i.e. above the speed of sound. The question asks specifically about a $200^{\circ} C$ increase in temperature in the atmosphere. This qualifies as "significant" heating, and the ...


7

The Moon has no atmosphere, so meteors would not heat up and glow as they descended, as they do on Earth. Comets, however, reflect light from the Sun, and thus can be seen from any sufficiently dark location.


6

There are a few meteor showers that merit mentioning: Quadrantids: January 3, ZHR: 120 Eta Aquariids: May 6, ZHR: 60 Arietids: June 7, ZHR: 54 Perseids: August 12, ZHR: 90 Orionids: October 21, ZHR: 20 Geminids: December 14, ZHR: 120 Of course, these rate estimates are not absolute, and in rare cases some showers (for example, Leonids) can flare up, ...


6

The duration of the energy release has a huge effect on the destructive potential. A single stick of TNT has roughly 1 MJoule of energy which is released in a fraction of a second. [1] Spread the same 1 MJ over an hour and you get 277 W or roughly the same power consumption as an ATI Radeon HD 7970. [2] Sources: [1] http://en.wikipedia.org/wiki/Dynamite ...


5

The flash seen in this video may not be the glow of initial entry since the camera angle is angled somewhat along the path of the meteor; it is likely the active burning after the meteor has already entered the atmosphere. The mesosphere begins about 50 km above the earth's surface. However, the speed of sound in this region is a bit lower than the speed ...


5

I suspect this is a formidably difficult question to answer from first principles. The cooling depends on the details of the air flow around your cylinder, and also on the temperature difference. An aeroplane flies at an altitude where the temperature is -50C, so the cooling is obviously going to be very different to say a baseball travelling at sea level. ...


5

Two terminology issues first. First, cosmology is the study of how the universe began and what will ultimately happen to it. Pieces of rock in our solar system have nothing to do with cosmology. Second, a meteoroid is a small solid body in the solar system. A meteor is what we call such a body while it is falling through our atmosphere, usually glowing hot ...


5

As of right now we have no way of deflecting an asteroid on its way to hitting the Earth. However there are lots of organisations tasked with looking into the issue. The Wikipedia article on Asteroid impact avoidance would be a good place to start. Also see the NASA Near Earth Orbit site for lots more background. You are quite correct than the kinetic ...


5

The heat of atmospheric reentry and the sudden impact of, um, impact, certainly metamorphosize the minerals in a meteorite. That's a whole fascinating branch of geology. Before the metamorphosis, though, I don't think either of the other terms fit, unless you're talking about a meteor that has already been processed through a large body as lava and ejected ...


5

It's been a while since I set out specifically to watch a meteor shower but back when I used to do so I would typically watch in a prone position. Either lying on a blanket or slightly inclined on a folding lounge chair (and sometimes lying on a picnic table. The main reason, at least for me, is that you want to try to see as much of the visible sky as ...


5

This somewhat depends on your definition. It is reasonably likely that a huge impact on Earth could knock rocks into a loose orbit around us, or at least around the sun but coming close to us. It seems likely that some of these would eventually fall back to the Earth, being Earth-origin meteorites. The second possibility, that they landed on another world ...


3

When this meteorite entered the atmosphere, it was traveling at approx 36000 miles per hour. Now consider this fact; I have a roof rack that creates a howling sound when I speed up to 100 kph. This howling sound is caused by air moving past the roof rack. I can hear this howling sound with my car windows closed. If there were sensors mounted on the vehicle ...


3

As a high velocity meteoroid encounters denser atmosphere, there exists an increasing pressure difference between its frontal and rearward areas. This plus the very high temperatures create the instabilities that ultimately cause the sudden destruction of the body. Chrondite meteoroids are more vulnerable to this type of destruction than iron/nickel bodies ...


2

Most meteor showers are associated with comets, they are either remnants of a dead comet or simply orbiting in the same orbit as the associated comet, so their strength can be predicted by how closely earth intersects with the orbit, where the observer is on Earth, and at what point the biggest "clump" of cometary fragments are in the orbit. To use your ...


2

Another issue with the object getting heated up, apart from the concerns already raised by AlanSE, is that even if you can put the air at the front of the object at 500 K, that doesn't bring the object heat to 500 K, not even after a long time, and certainly over its whole volume ! The main issues the size of the object and the fact that there will heat ...


2

At 4:30, light from the burning meteor reached the video camera. At that time the meteor was still in the air and it did not generate the boom. After 150 seconds the sound waves reached the video which means that the point where the boom were generated was at a distance of 333 m/s x 150 s = 49.95 Km from the spot where the video was shot. The reason for ...


1

There is only a relative handful of meteorites on Earth known to come from Mars. The odds of any chunk of rock making two trips and being discovered/recovered by humans are incredibly long. If that somehow did happen nevertheless, it would be pretty unambiguous to verify. Earth rocks have distinctive chemical and geological (and even more distinctive ...


1

The energy released is roughly the same regardless of the altitude of the explosion, and it is delivered to the atmosphere as well as objects on the ground. For higher altitudes, however, more and more of the energy is taken up by the atmosphere, and less of it reaches the ground. The Tunguska blast offers a good comparison. Though it was admittedly an ...



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