What is the difference between a 'rocket' and a 'missile'

Question

Someone pointed out on the BBC News that the Malaysian plane was hit not by a 'rocket' but by a 'missile'. From the dictionary definitions I have looked up I cannot tell the difference.

Missile An object which is forcibly propelled at a target, either by hand or from a mechanical weapon.

Rocket a cylindrical projectile that can be propelled to a great height or distance by the combustion of its contents...

Oxford Dictionary of English

Is it therefore the case that a rocket is always a missile, but that a missile is not necessarily a rocket? A cricket ball can be regarded as a missile but is clearly not a rocket. But why could the type of weapon which it is believed brought down Flight MH17 not be described as a 'rocket'?

Answer 1

A rocket is so called on the basis of its mode of self-propulsion. A missile is so called on the basis of its being propelled, by a rocket engine or otherwise, for the purpose of doing damage, as a weapon. The two categories overlap considerably, since rockets are commonly used as propulsion for missiles, with or without in-flight guidance systems. Put an explosive warhead on top of an Atlas rocket, and launch it at an enemy (or practice target), the whole assembly becomes a missile. Put a Mercury capsule on top with John Glenn inside, it is a rocket but not a missile. The weapon that reportedly brought down the Malaysian airliner was (or is, if considered generically) both a rocket and a missile, and can properly be termed either one—though without the explosive payload that transforms it from mere rocket to missile it would probably not have brought the plane down, so missile is the more adequate term in this case.

Answer 2

There's a further definition for missile:

a weapon that is self-propelled or directed by remote control, carrying conventional or nuclear explosive

Emphasis mine.

While rockets have been and still are used as weapons, the word rocket does not convey the sense of being guided that missile does.

Answer 3

Summary: a rocket is a means of propulsion; a missile is something that is propelled (possibly by a rocket).

A rocket is an engine that propels an object by combustion, where both the both the propellant and oxidizer are contained in the engine, as opposed to being input from outside (e.g., the oxygen does not come from the surrounding air or water).

A missile is any object that is propelled (typically in 3 dimensions, as through space, air, or water).

Some missiles are propelled by an exterior force, and after that initial push are simply ballistic: falling. Others have an on-board engine: they are self-propelled. A combination would be essentially just falling but with one or more small engines on board that can change the trajectory slightly.

Of the latter (missiles with on-board engines), some have self-contained engines; others can make use of oxygen in the fluid they pass through. Of those that have engines, the best known have rocket engines.

Answer 4

It seems to me, that the confusion regarding the word missile, comes from it having two uses/meanings. As this link shows http://dictionary.cambridge.org/dictionary/british/missile?q=missile , it has a particular, military meaning and, a general meaning.

It can be a particular kind of military weapon, but it can be any object that is thrown with the intention of causing injury or damage.

In the context of the question, which is the Malaysian airliner that crashed in Ukraine, the particular, military meaning applies. The introduction of the article at the following link http://en.wikipedia.org/wiki/Missile , states "In a modern military usage, a missile, or guided missile, is a self-propelled guided weapon system, as opposed to an unguided self-propelled munition, referred to as just a rocket."

In other words, in a military context, a rocket is an unguided, rocket-powered weapon, with no steering ability. A missile is a self-propelled weapon, often rocket-powered (but not always), that has some kind of guidance system so that it can steer in flight, towards its target.

That would be why someone pointed out on BBC News that the Malaysian plane was hit not by a 'rocket' but by a 'missile'. It is very unlikely that an unguided rocket fired from land, which requires a direct hit on its target, to explode, would be able to hit an aircraft in flight, especially one flying as high as that airliner was reported to be. Potential attackers would have to use a missile, which can steer towards its target and would have a proximity fuse http://en.wikipedia.org/wiki/Proximity_fuze , which means that it would not require a direct hit on its target, to explode.

Answer 5

Rocket's carry both their propellant and oxidizer, and are usually unguided - their trajectory is determined and fixed at launch time, however they may have the capacity for small course corrections. They are not capable of completely changing trajectory or assuming a guided path, that would make them a (guided) missile.

However, it is not that cut and dry. ICBM (inter-continental ballistic missiles) fit the definition of a rocket - they follow a fairly set trajectory after some initial guidance, with only the capacity to make small course corrections. And it would not be in any way out of the ordinary to refer to such a thing as a "rocket". However the official name is missile.

It is absolutely true that the term "missile" can refer to any propelled object, and historically was so. So sling shots, catapult rounds, even arrows, could all technically be called missiles. However, the common usage meaning of "missile" today is a guided military weapon system that has the capacity to assume a non-kinetic guided trajectory, change course, and possibly lock onto and follow targets. Ground to air missiles and air-to-air missiles usually carry both their fuel and oxidizer, giving them something in common to rockets (although are never referred to as such), whereas air-to-ground missiles usually have air-breathing jet engines, and are often referred to as "cruise missiles", because they can cruise for long distances while following a controlled, guided path.

Back to the ICBM example - rockets are usually BIG. So if a "missile" was large enough, and did not have an air-breathing engine, it would probably be referred to as a rocket even if it was highly controlled and guided.

Missiles are almost exclusively military - humans will always be taking rockets to the Moon and maybe even Mars, never a missile ;-)

Answer 6

I'm just gonna add here that the neat claim that missiles are always guided isn't quite backed by some usage examples. For instance "guided missile destroyer" seems a pleonasm, but it's a well established term.

Also, there seems to be a preference to use the term "guided rocket" instead of missile whenever a system is upgraded from unguided (or less guided) rockets to some with improved guidance/accuracy (which may be technically called missiles)... at least in Lockheed Martin terminology. For example:

• GMRLS: Guided Multiple Launch Rocket System
• DAGR: Direct Attack Guided Rocket

So it's common to see on Lockheed Martin's site (and on Wikipedia which seems to borrow the manufacturers' terminology) GMLRS being called rockets, despite their GPS guidance, while referring to ATACMS as missiles, even though there's not that much difference in terms of precision between ATACMS and GMLRS (although there is one in size and range).

Answer 7

A rocket is a type of jet engine: http://en.wikipedia.org/wiki/Rocket_engine.

A missile historically was a thrown projectile but is now any self-propelled guided weapon: http://en.wikipedia.org/wiki/Missile.