# Tag Info

40

If you see the same meteor, it of course only has one path - even while the apparent movement differs for different observers. What you basically do in that case is triangulation - which you could use with your known geographic location (and time for the observations, and the direction horizontally and vertically) reconstruct the flight path. That's a method ...

30

The comet sheds material each time it get close to the sun. The sun heats this dirty snow ball, the ice evaporates and tears dust and smaller rocks with it. These dust particles then follow a similar orbit around the sun as the comet. But as they are ejected with some velocity and react differently to the solar wind & radiation, their orbit is slightly ...

27

I'm a researcher at Curtin University working on the Desert Fireball Network. The DFN is the largest fireball observation network in the world, and our primary goal is to recover meteorites with orbital information attached. The traditional rule of thumb for meteorite-dropping events is a final luminous height below 35 km and a final luminous velocity below ...

19

The colour of a meteor depends mostly on its chemical composition emission spectrum. To simplify magnesium meteors are noted to have an emission spectrum which results in blue to green colour. Changing factors like adding additional metals and the speed of the meteor could results in a cyan meteor compared to a blue one. Source: NASA on meteors

18

Yes, but it depends on your reference system. If the meteor was moving East to West over England, it would appear to be going Left to Right from Norway, but Right to Left from Spain.

15

Your analysis is correct. Compression of the air is the cause of heating. You call this "simple" but the compression depends on the ability of the air to flow around the meteoroid, and as the modelling the hypersonic flow is far from trivial. "Air fiction" is the resistance to motion felt by an object moving relative to the air. That includes the reaction ...

13

The objects you are refering to are actually two different objects: asteroids and comets. Meteor and meteorite are other names for an asteroid, at a given time of its interaction with our planet. We'll get to that. So first, what is the difference between an asteroid and a comet? A comet is a small solar system body that display a "coma" (an ...

13

Yes, if the object is moving between the two of you then your reference systems are different. For example two people standing on opposite sides of a river. One sees it flowing from left to right, the other sees it flowing from right to left. The river, or meteor, has not itself changed direction, but you'll each describe the direction differently if you're ...

12

No, meteorites of the same shower look as coming from the same point in the sky. They are usually named according to the point they seen to come from, e.g. the leonids, or the perseids. The point, they seem to originate is a result of the relative velocity of the meteorites to the earth. Meteor showers are thought to be remnants of comets, hence the similar ...

11

There is, believe it or not, a scientific theory regarding this: panspermia. According to the panspermia hypothesis, microbes "hitch" a lift on bodies leaving a planet. They then travel through space and eventually land somewhere else. Panspermia involves three difficult phases of travel: Launch (as well as the impact event) Travel in the harsh environment ...

11

Fireballs are real but rare events. Meteors are formed when small rocks enter the atomsphere from space. Larger rocks or small asteroids will produce brighter meteors. The brightest meteors are called fireballs or bolides. It is not uncommon for parts of the rock that made the fireball to survive and can later be found as meteorites. A couple of things can ...

11

The comet releases lots of dust particles. The sunlight pushes these particles into orbits not quite the same as the comet Some particles will be pushed into faster orbits, some will be pushed into slower orbits. Over time the dust particles get spread out in a band that goes all the way around the sun. So we don't just see meteors in the years that the ...

10

It’s been a while since I studied this, and meteorites are very much not my field, so I’ll share my current understanding but would welcome corrections from those more informed :-) These meteorites are mostly iron with a small amount of nickel. For a given composition of iron and nickel, there are different crystal structures that can be formed. Of ...

10

Remember that the Earth, and the meteoroid, are both in orbit around the sun. As the meteoroid approaches Earth, it will also curve due to Earth's gravity. If you imagine the Earth to be stationary and the meteoroid to be moving in a straight line your intuition is likely to be wrong. The result of the complex dynamics is that there is no time or direction ...

10

Three millions. For this answer to be any fun, let's first assume that before removing the atmosphere, we have equipped all humans with oxygen supplies. In return, they are not allowed to go indoors or otherwise protect themselves. The size of meteors — as well as most other things in the Universe — has a distribution that is well described by a power-law. ...

9

Same reason as the explosion at the Tunguska event years ago: Pressure, due to boiling water. Meteors usually cme into our atmosphere at incredible speeds. At these speeds, the meteor is highly affected by the viscosity of air and is heated by compression (and a little bit of friction). This starts boiling the ice present in the meteor, leading to a ...

9

Even if a virus came to Earth from space, it would likely be harmless to life on Earth. Let's look at some biology numbers: Life on Earth uses 20 amino acids (out of about 400 considered chemically potential alternatives). The median length of a protein on Earth is about 300 amino acids. That's 20^300 combinations. And some proteins are 30,000 amino acids ...

8

First Shooting Star Seen from Mars space.com 2005 The background image shows the meteor near the top-left and the horizon at the bottom. A red arrow shows the direction of travel. The inset is a larger version of the meteor itself. The graph is a "light curve" that aided in tying the meteor to comet Wiseman–Skiff. (Image: © Nature/NASA/Spirit/F. ...

8

Physically, the air in front of the meteor is experiencing adiabatic compression. The jump values of density and temperature before and after the adiabatic shock are given by the Rankine-Hugoniot conditions. The analysis of those conditions reveal that the density jump is limited to a finite value, but the temperature jump before and after the shock is ...

7

The meteorite decelerated from perhaps 30000 mph through friction and impact with the atmosphere, and this made it heat up to an incredible temperature. At this point the rock was boiling and burning, and liquids within it , such as water, became gaseous. Some small explosions cast off burning pieces of the meteorite, and the major explosion was from the ...

7

I saw a zig zag meteorite in Bukuru, Northern Nigeria, when I was about 13 in 1959. That started from small to increasing swings, then went out near the horizon. For many years I puzzled about this, but rarely mentioned it, because no one would believe it. Years later I attended an astronomy lecture at college in London. I cornered the astronomer with this ...

7

A shooting star is simply the visible path a meteriod takes burning up in the atmosphere. As it flies through the atmosphere, it leaves a trail of fire, creating the streak of light you see. Before they enter the atmosphere, they are simply chunks of rock. They could form in one of many ways - be broken off of a planet, etc. After they do this: they look ...

7

Only very few meteors actually make it anywhere near the surface of Earth; most burn up 75–100 km above the surface. From your point of view, however, the curvature of Earth's surface may make it look as if they get much closer, and even fall below the horizon. But depending on where you live, the horizon often has quite a lot more background light (e.g. ...

7

Earth passed through the tail of Halley's Comet in 1910. It caused a bit of a panic due to claims that cyanogen detected in the tail would cause harm: https://en.wikipedia.org/wiki/Halley%27s_Comet#1910 Linked there is https://timesmachine.nytimes.com/timesmachine/1910/02/08/104920328.pdf (click for larger)

6

Asteroids are what are called minor planets - small inner solar system rocky bodies. Especially between Mars and Jupiter. Comets typically have highly elliptical orbits but they don't have to. The key defining feature of a comet is that it has a gaseous atmosphere and a tail when it passes close to the Sun. Comets are generally loose aggregations of ice, ...

6

I think the answer to this is that it doesn't have a name because such "ditches" don't occur for real meteor impacts. In movies and tv shows, these ditches are often shown as being caused by the meteor first hitting the ground at some angle, then sliding across the ground, digging out a ditch along the way, until they come to their final resting point where ...

6

There are some invariances that actually lend themselves well to estimating an answer to this question. From the Deep Impact mission white paper: A 1 mm projectile striking a target at 10 km/s will yield the same result as a 1 m projectile striking at the same speed, provided all distances are scaled by the same ratio of 1,000 = 1 m/1mm and all times are ...

5

Edited. No if you talk about the escape velocity form Earth. This follows simply from the fact that energy $E$ is conserved. An object that is not gravitationally bound to Earth has $E>0$ and hence $v>v_{\mathrm{esc}}$ when hitting ground. Yes, if you meant the escape velocity from the Solar system, because the Earth moves with \$v_{\rm Earth}=v_{\rm ...

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