Asteroids

None. Even the smallest planets are larger than the largest asteroids.

When a meteor enters the earth's atmosphere, friction with the air generates enormous amounts of heat, which causes the meteor to at least partially burn up.

Yes, asteroids in the Asteroid Belt are constantly moving due to the gravitational interactions among them and the influence of the Sun's gravity. Their orbits may change over time due to the gravitational pulls of nearby planets or other asteroids.

It depends on the mass and composition. It could have no effect at all to total extinction of all life.

1. Main Belt asteroids -- a band of asteroids located in the "missing planet" gap between Mars and Jupiter. None of these are economically attractive in a near term program because they are too far from Earth.
2. Amor asteroids -- asteroids whose orbits approach but do not cross Earth orbit, and whose orbits are further from the Sun than Earth's orbit (i.e., "outside-t" Earth orbit). Many have orbits which reside entirely between Earth and Mars. Some of these are economically attractive in the near term.
3. Apollo asteroids -- asteroids whose orbits cross Earth's orbit. Apollo asteroids spend most of their time outside Earth orbit. Many of these are economically attractive in the near term.
4. Aten asteroids -- asteroids whose orbits cross Earth's orbit. Unlike Apollos, Atens spend most of their time inside Earth orbit. A large percentage of known Atens are economically attractive in the near term.

I know of no such thing as the 'Cretaceous-theory'!

However you probably mean the The Cretaceous-Tertiary extinction event, which occurred approximately 65.5 million years ago.

If this is the case then, the theory regarding this is that, a comet or asteroid (an impactor) hit the Earth at this point and caused the extinction event.

Impactors frequently contain levels of the element iridium not found in normal Earth rocks, and a worldwide distributed spike in the iridium content of a specific geological layer would seem to support the fact that an impactor had a global affect.

However please note, that while much is made of the impactor theory for the extinction of the dinosaurs, the most recent geological research seems to prove definitively that dinosaurs were present on the planet for some hundreds of thousands of years after the iridium spike and thus, while the impactor certainly happened, it is not directly responsible for the demise of the dinosaurs.

See the related link below.

Unfortunately, not many. We can accurately measure its location and orbit, by watching the object for several months or years. We can make a good guess of its size, based on the brightness, since we know the distance pretty accurately. We can calculate the composition of the surface based on the spectrum of light that we see.

A couple of things that are very difficult to determine from here are the mass and density of the object. We can calculate these very accurately if the asteroid has a satellite, or if we send a space probe there to orbit the object. We've done that only for a very few asteroids.

He sold his paintings through "Artistic Impressions". Last time I googled, they still sell his paintings. They do home demonstrations.

Which asteroid? depending on its size, an asteroid impact could be devastating for life on Earth, though life would recover somehow eventually.

Asteroid: elatively small, inactive body, composed of rock, carbon or metal, which is orbiting the Sun. Comet: A relatively small, sometimes active object, which is composed of dirt and ices. Comets are characterised by dust and gas tails when in proximity to the Sun. Far from the Sun it is difficult to distinguish an asteroid from a comet. Meteoroid: A small particle from an asteroid or comet orbiting he Sun. Meteor:A meteoroid that is observed as it burns up in the Earth's atmosphere - a shooting star. Meteorite: A meteoroid that survives its passage through the Earth's atmosphere and impacts the Earth's surface.
A meteoroid is a meteor that hits earth and is recorded, a meteor just keeps orbiting, and orbiting the sun

They are referred to as asteroids.

If it enters a planet's atmosphere it can heat up and start to burn and turn into a fireball.

The asteroid belt is a ring of scattered space rock located between the orbits of mars and Jupiter, the reason why it is in it's current location is because the gas giant Jupiter's massive gravitational pull prevents the space rocks from colliding together and creating a planet. It is the left over material from when the solar system was forming that was unable to form into planets.

"Meteor" (1979). Stars Sean Connery, Natalie Wood, Karl Malden, Brian Keith, Martin Landau, Trevor Howard, Henry Fonda.

Technically this is a comet film: "Deep Impact" (1998). Stars Robert Duvall, Morgan Freeman, Tea Leoni, Elijah Wood, Vanessa Redgrave, Maximilian Schell, James Cromwell, Jon Favreau, Mary McCormack, Leelee Sobieski.

Technically this is an asteroid film: "Armageddon" (1998). Stars Bruce Willis, Billy Bob Thornton, Ben Affleck, Liv Tyler, Steve Buscemi, Owen Wilson.

No. And even then, something that large would not be conisdered an asteroid. Such an object would be more than 3 times the diameter of Jupiter, the largest planet in the solar system.

An asteroid, because the orbits of the asteroids are nearer to the earth than the comets.

No, it does not have enough mass to hold any "atmosphere".

Yes, asteroid images can become blurry due to outgassing as they are heated by the Sun. When an asteroid's surface warms, volatile materials may sublimate, creating gas and dust that can obscure the asteroid's features. This outgassing can lead to a temporary hazy appearance in images captured by telescopes, affecting the clarity and resolution of the observations.

Asteroids, even very large ones, actually come close to earth regularly and cause no harm and no effect on life on earth. The concern would be a large asteroid crashing into the earth.